diff --git a/taiga/base/api/fields.py b/taiga/base/api/fields.py
index a06a7c60..e528a2b6 100644
--- a/taiga/base/api/fields.py
+++ b/taiga/base/api/fields.py
@@ -618,13 +618,24 @@ class ChoiceField(WritableField):
         return value
 
 
+class InvalidEmailValidationError(ValidationError):
+    pass
+
+
+class InvalidDomainValidationError(ValidationError):
+    pass
+
+
 def validate_user_email_allowed_domains(value):
-    validators.validate_email(value)
+    try:
+        validators.validate_email(value)
+    except ValidationError as e:
+        raise InvalidEmailValidationError(e)
 
     domain_name = value.split("@")[1]
 
     if settings.USER_EMAIL_ALLOWED_DOMAINS and domain_name not in settings.USER_EMAIL_ALLOWED_DOMAINS:
-        raise ValidationError(_("You email domain is not allowed"))
+        raise InvalidDomainValidationError(_("You email domain is not allowed"))
 
 
 class EmailField(CharField):
diff --git a/taiga/projects/api.py b/taiga/projects/api.py
index 31a6cf84..cbe4a897 100644
--- a/taiga/projects/api.py
+++ b/taiga/projects/api.py
@@ -653,7 +653,6 @@ class ProjectTemplateViewSet(ModelCrudViewSet):
 class MembershipViewSet(BlockedByProjectMixin, ModelCrudViewSet):
     model = models.Membership
     admin_serializer_class = serializers.MembershipAdminSerializer
-    admin_validator_class = validators.MembershipAdminValidator
     serializer_class = serializers.MembershipSerializer
     validator_class = validators.MembershipValidator
     permission_classes = (permissions.MembershipPermission,)
@@ -680,12 +679,6 @@ class MembershipViewSet(BlockedByProjectMixin, ModelCrudViewSet):
         else:
             return self.serializer_class
 
-    def get_validator_class(self):
-        if self.action == "create":
-            return self.admin_validator_class
-
-        return self.validator_class
-
     def _check_if_project_can_have_more_memberships(self, project, total_new_memberships):
         (can_add_memberships, error_type) = services.check_if_project_can_have_more_memberships(
             project,
@@ -700,7 +693,10 @@ class MembershipViewSet(BlockedByProjectMixin, ModelCrudViewSet):
 
     @list_route(methods=["POST"])
     def bulk_create(self, request, **kwargs):
-        validator = validators.MembersBulkValidator(data=request.DATA)
+        context = {
+            "request": request
+        }
+        validator = validators.MembersBulkValidator(data=request.DATA, context=context)
         if not validator.is_valid():
             return response.BadRequest(validator.errors)
 
diff --git a/taiga/projects/services/members.py b/taiga/projects/services/members.py
index 8c9bf265..3cd9b514 100644
--- a/taiga/projects/services/members.py
+++ b/taiga/projects/services/members.py
@@ -16,11 +16,16 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+from taiga.base.exceptions import ValidationError
 from taiga.base.utils import db, text
+from taiga.users.models import User
+
+from django.core.validators import validate_email
 from django.utils.translation import ugettext as _
 
 from .. import models
 
+
 def get_members_from_bulk(bulk_data, **additional_fields):
     """Convert `bulk_data` into a list of members.
 
@@ -32,6 +37,15 @@ def get_members_from_bulk(bulk_data, **additional_fields):
     members = []
     for data in bulk_data:
         data_copy = data.copy()
+        username = data_copy.pop("username")
+        try:
+            validate_email(username)
+            data_copy["email"] = username
+
+        except ValidationError:
+            user = User.objects.filter(username=username).first()
+            data_copy["user_id"] = user.id
+
         data_copy.update(additional_fields)
         members.append(models.Membership(**data_copy))
     return members
@@ -40,7 +54,7 @@ def get_members_from_bulk(bulk_data, **additional_fields):
 def create_members_in_bulk(bulk_data, callback=None, precall=None, **additional_fields):
     """Create members from `bulk_data`.
 
-    :param bulk_data: List of dicts `{"project_id": <>, "role_id": <>, "email": <>}`.
+    :param bulk_data: List of dicts `{"project_id": <>, "role_id": <>, "username": <>}`.
     :param callback: Callback to execute after each task save.
     :param additional_fields: Additional fields when instantiating each task.
 
@@ -116,7 +130,7 @@ def check_if_project_can_have_more_memberships(project, total_new_memberships):
     """
     if project.owner is None:
         return False, _("Project without owner")
-        
+
     if project.is_private:
         total_memberships = project.memberships.count() + total_new_memberships
         max_memberships = project.owner.max_memberships_private_projects
diff --git a/taiga/projects/validators.py b/taiga/projects/validators.py
index ec97aadd..18fb95c0 100644
--- a/taiga/projects/validators.py
+++ b/taiga/projects/validators.py
@@ -16,15 +16,19 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+from django.core.validators import validate_email
 from django.db.models import Q
 from django.utils.translation import ugettext as _
 
 from taiga.base.api import serializers
 from taiga.base.api import validators
+from taiga.base.api.fields import validate_user_email_allowed_domains, InvalidEmailValidationError
 from taiga.base.exceptions import ValidationError
 from taiga.base.fields import JSONField
 from taiga.base.fields import PgArrayField
-from taiga.users.models import Role
+from taiga.users.models import User, Role
+from taiga.users import filters as user_filters
+
 
 from .tagging.fields import TagsField
 
@@ -112,21 +116,24 @@ class IssueTypeValidator(DuplicatedNameInProjectValidator, validators.ModelValid
 ######################################################
 
 class MembershipValidator(validators.ModelValidator):
-    email = serializers.EmailField(required=True)
+    username = serializers.CharField(required=True)
+    # email = serializers.EmailField(required=False)
+    # user = serializers.PrimaryKeyRelatedField(required=False)
 
     class Meta:
         model = models.Membership
-        # IMPORTANT: Maintain the MembershipAdminSerializer Meta up to date
-        # with this info (excluding here user_email and email)
-        read_only_fields = ("user",)
-        exclude = ("token", "email")
+        read_only_fields = ("user", "email")
 
-    def validate_email(self, attrs, source):
-        project = attrs.get("project", None)
+    def restore_object(self, attrs, instance=None):
+        username = attrs.pop("username", None)
+        obj = super(MembershipValidator, self).restore_object(attrs, instance=instance)
+        obj.username = username
+        return obj
+
+    def _validate_member_doesnt_exist(self, attrs, email):
+        project = attrs.get("project", None if self.object is None else self.object.project)
         if project is None:
-            project = self.object.project
-
-        email = attrs[source]
+            return attrs
 
         qs = models.Membership.objects.all()
 
@@ -139,14 +146,12 @@ class MembershipValidator(validators.ModelValidator):
                        Q(project_id=project.id, email=email))
 
         if qs.count() > 0:
-            raise ValidationError(_("Email address is already taken"))
-
-        return attrs
+            raise ValidationError(_("The user yet exists in the project"))
 
     def validate_role(self, attrs, source):
-        project = attrs.get("project", None)
+        project = attrs.get("project", None if self.object is None else self.object.project)
         if project is None:
-            project = self.object.project
+            return attrs
 
         role = attrs[source]
 
@@ -155,10 +160,35 @@ class MembershipValidator(validators.ModelValidator):
 
         return attrs
 
+    def validate_username(self, attrs, source):
+        username = attrs.get(source, None)
+        try:
+            validate_user_email_allowed_domains(username)
+
+        except ValidationError:
+            # If the validation comes from a request let's check the user is a valid contact
+            request = self.context.get("request", None)
+            if request is not None and request.user.is_authenticated():
+                valid_usernames = request.user.contacts_visible_by_user(request.user).values_list("username", flat=True)
+                if username not in valid_usernames:
+                    raise ValidationError(_("The user must be a valid contact"))
+
+        user = User.objects.filter(Q(username=username) | Q(email=username)).first()
+        if user is not None:
+            email = user.email
+            self.user = user
+
+        else:
+            email = username
+
+        self.email = email
+        self._validate_member_doesnt_exist(attrs, email)
+        return attrs
+
     def validate_is_admin(self, attrs, source):
-        project = attrs.get("project", None)
+        project = attrs.get("project", None if self.object is None else self.object.project)
         if project is None:
-            project = self.object.project
+            return attrs
 
         if (self.object and self.object.user):
             if self.object.user.id == project.owner_id and not attrs[source]:
@@ -171,20 +201,34 @@ class MembershipValidator(validators.ModelValidator):
 
         return attrs
 
+    def is_valid(self):
+        errors = super().is_valid()
+        if hasattr(self, "email") and self.object is not None:
+            self.object.email = self.email
 
-class MembershipAdminValidator(MembershipValidator):
-    class Meta:
-        model = models.Membership
-        # IMPORTANT: Maintain the MembershipSerializer Meta up to date
-        # with this info (excluding there user_email and email)
-        read_only_fields = ("user",)
-        exclude = ("token",)
+        if hasattr(self, "user") and self.object is not None:
+            self.object.user = self.user
+
+        return errors
 
 
 class _MemberBulkValidator(validators.Validator):
-    email = serializers.EmailField()
+    username = serializers.CharField()
     role_id = serializers.IntegerField()
 
+    def validate_username(self, attrs, source):
+        username = attrs.get(source)
+        try:
+            validate_user_email_allowed_domains(username)
+        except InvalidEmailValidationError:
+            # If the validation comes from a request let's check the user is a valid contact
+            request = self.context.get("request", None)
+            if request is not None and request.user.is_authenticated():
+                valid_usernames = set(request.user.contacts_visible_by_user(request.user).values_list("username", flat=True))
+                if username not in valid_usernames:
+                    raise ValidationError(_("The user must be a valid contact"))
+
+        return attrs
 
 class MembersBulkValidator(ProjectExistsValidator, validators.Validator):
     project_id = serializers.IntegerField()
@@ -192,12 +236,10 @@ class MembersBulkValidator(ProjectExistsValidator, validators.Validator):
     invitation_extra_text = serializers.CharField(required=False, max_length=255)
 
     def validate_bulk_memberships(self, attrs, source):
-        filters = {
-            "project__id": attrs["project_id"],
-            "id__in": [r["role_id"] for r in attrs["bulk_memberships"]]
-        }
+        project_id = attrs["project_id"]
+        role_ids = [r["role_id"] for r in attrs["bulk_memberships"]]
 
-        if Role.objects.filter(**filters).count() != len(set(filters["id__in"])):
+        if Role.objects.filter(project_id=project_id, id__in=role_ids).count() != len(set(role_ids)):
             raise ValidationError(_("Invalid role ids. All roles must belong to the same project."))
 
         return attrs
diff --git a/taiga/users/api.py b/taiga/users/api.py
index a9f1c957..b67882d6 100644
--- a/taiga/users/api.py
+++ b/taiga/users/api.py
@@ -46,17 +46,17 @@ from . import validators
 from . import permissions
 from . import filters as user_filters
 from . import services
+from . import utils as user_utils
 from .signals import user_cancel_account as user_cancel_account_signal
 
-
 class UsersViewSet(ModelCrudViewSet):
     permission_classes = (permissions.UserPermission,)
     admin_serializer_class = serializers.UserAdminSerializer
     serializer_class = serializers.UserSerializer
     admin_validator_class = validators.UserAdminValidator
     validator_class = validators.UserValidator
-    queryset = models.User.objects.all().prefetch_related("memberships")
     filter_backends = (MembersFilterBackend,)
+    model = models.User
 
     def get_serializer_class(self):
         if self.action in ["partial_update", "update", "retrieve", "by_username"]:
@@ -74,6 +74,12 @@ class UsersViewSet(ModelCrudViewSet):
 
         return self.validator_class
 
+    def get_queryset(self):
+        qs = super().get_queryset()
+        qs = qs.prefetch_related("memberships")
+        qs = user_utils.attach_extra_info(qs, user=self.request.user)
+        return qs
+
     def create(self, *args, **kwargs):
         raise exc.NotSupported()
 
@@ -91,7 +97,7 @@ class UsersViewSet(ModelCrudViewSet):
         return response.Ok(serializer.data)
 
     def retrieve(self, request, *args, **kwargs):
-        self.object = get_object_or_404(models.User, **kwargs)
+        self.object = get_object_or_404(self.get_queryset(), **kwargs)
         self.check_permissions(request, 'retrieve', self.object)
         serializer = self.get_serializer(self.object)
         return response.Ok(serializer.data)
diff --git a/taiga/users/filters.py b/taiga/users/filters.py
index 46dd88ac..03f7b10e 100644
--- a/taiga/users/filters.py
+++ b/taiga/users/filters.py
@@ -17,13 +17,24 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 from taiga.base.filters import PermissionBasedFilterBackend
+from taiga.base.utils.db import to_tsquery
+
 from . import services
 
 
 class ContactsFilterBackend(PermissionBasedFilterBackend):
     def filter_queryset(self, user, request, queryset, view):
-        qs = queryset.filter(is_active=True)
-        project_ids = services.get_visible_project_ids(user, request.user)
-        qs = qs.filter(memberships__project_id__in=project_ids)
-        qs = qs.exclude(id=user.id)
+        qs = user.contacts_visible_by_user(request.user)
+        q = request.QUERY_PARAMS.get('q', None)
+        if q:
+            table = qs.model._meta.db_table
+            where_clause = ("""
+                to_tsvector('english_nostop',
+                            coalesce({table}.username, '') || ' ' ||
+                            coalesce({table}.full_name) || ' ' ||
+                            coalesce({table}.email, '')) @@ to_tsquery('english_nostop', %s)
+            """.format(table=table))
+
+            qs = qs.extra(where=[where_clause], params=[to_tsquery(q)])
+
         return qs.distinct()
diff --git a/taiga/users/models.py b/taiga/users/models.py
index e0f6a8c9..499b094c 100644
--- a/taiga/users/models.py
+++ b/taiga/users/models.py
@@ -45,6 +45,8 @@ from taiga.permissions.choices import MEMBERS_PERMISSIONS
 from taiga.projects.choices import BLOCKED_BY_OWNER_LEAVING
 from taiga.projects.notifications.choices import NotifyLevel
 
+from . import services
+
 
 def get_user_model_safe():
     """
@@ -258,6 +260,13 @@ class User(AbstractBaseUser, PermissionsMixin):
     def get_full_name(self):
         return self.full_name or self.username or self.email
 
+    def contacts_visible_by_user(self, user):
+        qs = User.objects.filter(is_active=True)
+        project_ids = services.get_visible_project_ids(self, user)
+        qs = qs.filter(memberships__project_id__in=project_ids)
+        qs = qs.exclude(id=self.id)        
+        return qs
+
     def save(self, *args, **kwargs):
         get_token_for_user(self, "cancel_account")
         super().save(*args, **kwargs)
diff --git a/taiga/users/serializers.py b/taiga/users/serializers.py
index a720e46e..1f6e0835 100644
--- a/taiga/users/serializers.py
+++ b/taiga/users/serializers.py
@@ -54,7 +54,6 @@ class UserSerializer(serializers.LightSerializer):
     big_photo = MethodField()
     gravatar_id = MethodField()
     roles = MethodField()
-    projects_with_me = MethodField()
 
     def get_full_name_display(self, obj):
         return obj.get_full_name() if obj else ""
@@ -69,21 +68,10 @@ class UserSerializer(serializers.LightSerializer):
         return get_user_gravatar_id(user)
 
     def get_roles(self, user):
-        return user.memberships. order_by("role__name").values_list("role__name", flat=True).distinct()
+        if hasattr(user, "roles_attr"):
+            return user.roles_attr
 
-    def get_projects_with_me(self, user):
-        request = self.context.get("request", None)
-        requesting_user = request and request.user or None
-
-        if not requesting_user or not requesting_user.is_authenticated():
-            return []
-
-        else:
-            project_ids = requesting_user.memberships.values_list("project__id", flat=True)
-            memberships = user.memberships.filter(project__id__in=project_ids)
-            project_ids = memberships.values_list("project__id", flat=True)
-            projects = Project.objects.filter(id__in=project_ids)
-            return ContactProjectDetailSerializer(projects, many=True).data
+        return user.memberships.order_by("role__name").values_list("role__name", flat=True).distinct()
 
 
 class UserAdminSerializer(UserSerializer):
diff --git a/taiga/users/utils.py b/taiga/users/utils.py
new file mode 100644
index 00000000..9101a63c
--- /dev/null
+++ b/taiga/users/utils.py
@@ -0,0 +1,44 @@
+# -*- coding: utf-8 -*-
+# Copyright (C) 2014-2016 Andrey Antukh <niwi@niwi.nz>
+# Copyright (C) 2014-2016 Jesús Espino <jespinog@gmail.com>
+# Copyright (C) 2014-2016 David Barragán <bameda@dbarragan.com>
+# Copyright (C) 2014-2016 Alejandro Alonso <alejandro.alonso@kaleidos.net>
+# Copyright (C) 2014-2016 Anler Hernández <hello@anler.me>
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+def attach_roles(queryset, as_field="roles_attr"):
+    """Attach roles to each object of the queryset.
+
+    :param queryset: A Django user stories queryset object.
+    :param as_field: Attach the roles as an attribute with this name.
+
+    :return: Queryset object with the additional `as_field` field.
+    """
+    model = queryset.model
+    sql = """SELECT ARRAY(
+                    SELECT DISTINCT(users_role.name)
+                      FROM projects_membership
+                INNER JOIN users_role ON users_role.id = projects_membership.role_id
+                     WHERE projects_membership.user_id = {tbl}.id
+                  ORDER BY users_role.name)
+    """
+    sql = sql.format(tbl=model._meta.db_table)
+    queryset = queryset.extra(select={as_field: sql})
+    return queryset
+
+
+def attach_extra_info(queryset, user=None):
+    queryset = attach_roles(queryset)
+    return queryset
diff --git a/tests/integration/resources_permissions/test_projects_choices_resources.py b/tests/integration/resources_permissions/test_projects_choices_resources.py
index 504b6a6f..5399e354 100644
--- a/tests/integration/resources_permissions/test_projects_choices_resources.py
+++ b/tests/integration/resources_permissions/test_projects_choices_resources.py
@@ -1856,24 +1856,28 @@ def test_membership_update(client, data):
 
     membership_data = serializers.MembershipSerializer(data.public_membership).data
     membership_data["token"] = "test"
+    membership_data["username"] = data.public_membership.user.email
     membership_data = json.dumps(membership_data)
     results = helper_test_http_method(client, 'put', public_url, membership_data, users)
     assert results == [401, 403, 403, 403, 200]
 
     membership_data = serializers.MembershipSerializer(data.private_membership1).data
     membership_data["token"] = "test"
+    membership_data["username"] = data.private_membership1.user.email
     membership_data = json.dumps(membership_data)
     results = helper_test_http_method(client, 'put', private1_url, membership_data, users)
     assert results == [401, 403, 403, 403, 200]
 
     membership_data = serializers.MembershipSerializer(data.private_membership2).data
     membership_data["token"] = "test"
+    membership_data["username"] = data.private_membership2.user.email
     membership_data = json.dumps(membership_data)
     results = helper_test_http_method(client, 'put', private2_url, membership_data, users)
     assert results == [401, 403, 403, 403, 200]
 
     membership_data = serializers.MembershipSerializer(data.blocked_membership).data
     membership_data["token"] = "test"
+    membership_data["username"] = data.blocked_membership.user.email
     membership_data = json.dumps(membership_data)
     results = helper_test_http_method(client, 'put', blocked_url, membership_data, users)
     assert results == [401, 403, 403, 403, 451]
@@ -1972,29 +1976,33 @@ def test_membership_create(client, data):
     ]
 
     membership_data = serializers.MembershipSerializer(data.public_membership).data
-    membership_data["id"] = None
-    membership_data["email"] = "test1@test.com"
+    del(membership_data["id"])
+    del(membership_data["user"])
+    membership_data["username"] = "test1@test.com"
     membership_data = json.dumps(membership_data)
     results = helper_test_http_method(client, 'post', url, membership_data, users)
     assert results == [401, 403, 403, 403, 201]
 
     membership_data = serializers.MembershipSerializer(data.private_membership1).data
-    membership_data["id"] = None
-    membership_data["email"] = "test2@test.com"
+    del(membership_data["id"])
+    del(membership_data["user"])
+    membership_data["username"] = "test2@test.com"
     membership_data = json.dumps(membership_data)
     results = helper_test_http_method(client, 'post', url, membership_data, users)
     assert results == [401, 403, 403, 403, 201]
 
     membership_data = serializers.MembershipSerializer(data.private_membership2).data
-    membership_data["id"] = None
-    membership_data["email"] = "test3@test.com"
+    del(membership_data["id"])
+    del(membership_data["user"])
+    membership_data["username"] = "test3@test.com"
     membership_data = json.dumps(membership_data)
     results = helper_test_http_method(client, 'post', url, membership_data, users)
     assert results == [401, 403, 403, 403, 201]
 
     membership_data = serializers.MembershipSerializer(data.blocked_membership).data
-    membership_data["id"] = None
-    membership_data["email"] = "test4@test.com"
+    del(membership_data["id"])
+    del(membership_data["user"])
+    membership_data["username"] = "test4@test.com"
     membership_data = json.dumps(membership_data)
     results = helper_test_http_method(client, 'post', url, membership_data, users)
     assert results == [401, 403, 403, 403, 451]
@@ -2014,8 +2022,8 @@ def test_membership_action_bulk_create(client, data):
     bulk_data = {
         "project_id": data.public_project.id,
         "bulk_memberships": [
-            {"role_id": data.public_membership.role.pk, "email": "test1@test.com"},
-            {"role_id": data.public_membership.role.pk, "email": "test2@test.com"},
+            {"role_id": data.public_membership.role.pk, "username": "test1@test.com"},
+            {"role_id": data.public_membership.role.pk, "username": "test2@test.com"},
         ]
     }
     bulk_data = json.dumps(bulk_data)
@@ -2025,8 +2033,8 @@ def test_membership_action_bulk_create(client, data):
     bulk_data = {
         "project_id": data.private_project1.id,
         "bulk_memberships": [
-            {"role_id": data.private_membership1.role.pk, "email": "test1@test.com"},
-            {"role_id": data.private_membership1.role.pk, "email": "test2@test.com"},
+            {"role_id": data.private_membership1.role.pk, "username": "test1@test.com"},
+            {"role_id": data.private_membership1.role.pk, "username": "test2@test.com"},
         ]
     }
     bulk_data = json.dumps(bulk_data)
@@ -2036,8 +2044,8 @@ def test_membership_action_bulk_create(client, data):
     bulk_data = {
         "project_id": data.private_project2.id,
         "bulk_memberships": [
-            {"role_id": data.private_membership2.role.pk, "email": "test1@test.com"},
-            {"role_id": data.private_membership2.role.pk, "email": "test2@test.com"},
+            {"role_id": data.private_membership2.role.pk, "username": "test1@test.com"},
+            {"role_id": data.private_membership2.role.pk, "username": "test2@test.com"},
         ]
     }
     bulk_data = json.dumps(bulk_data)
@@ -2047,8 +2055,8 @@ def test_membership_action_bulk_create(client, data):
     bulk_data = {
         "project_id": data.blocked_project.id,
         "bulk_memberships": [
-            {"role_id": data.blocked_membership.role.pk, "email": "test1@test.com"},
-            {"role_id": data.blocked_membership.role.pk, "email": "test2@test.com"},
+            {"role_id": data.blocked_membership.role.pk, "username": "test1@test.com"},
+            {"role_id": data.blocked_membership.role.pk, "username": "test2@test.com"},
         ]
     }
     bulk_data = json.dumps(bulk_data)
diff --git a/tests/integration/test_memberships.py b/tests/integration/test_memberships.py
index 70d3d198..b9c3dc95 100644
--- a/tests/integration/test_memberships.py
+++ b/tests/integration/test_memberships.py
@@ -30,8 +30,8 @@ pytestmark = pytest.mark.django_db
 
 
 def test_get_members_from_bulk():
-    data = [{"role_id": "1", "email": "member1@email.com"},
-            {"role_id": "1", "email": "member2@email.com"}]
+    data = [{"role_id": "1", "username": "member1@email.com"},
+            {"role_id": "1", "username": "member2@email.com"}]
     members = services.get_members_from_bulk(data, project_id=1)
 
     assert len(members) == 2
@@ -39,10 +39,65 @@ def test_get_members_from_bulk():
     assert members[1].email == "member2@email.com"
 
 
+def test_create_member_using_email(client):
+    project = f.ProjectFactory()
+    john = f.UserFactory.create()
+    joseph = f.UserFactory.create()
+    tester = f.RoleFactory(project=project, name="Tester")
+    f.MembershipFactory(project=project, user=john, is_admin=True)
+    url = reverse("memberships-list")
+
+    data = {"project": project.id, "role": tester.pk, "username": joseph.email}
+    client.login(john)
+    response = client.json.post(url, json.dumps(data))
+
+    assert response.status_code == 201
+    assert response.data["email"] == joseph.email
+
+
+def test_create_member_using_username_without_being_contacts(client):
+    project = f.ProjectFactory()
+    john = f.UserFactory.create()
+    joseph = f.UserFactory.create()
+    tester = f.RoleFactory(project=project, name="Tester")
+    f.MembershipFactory(project=project, user=john, is_admin=True)
+    url = reverse("memberships-list")
+
+    data = {"project": project.id, "role": tester.pk, "username": joseph.username}
+    client.login(john)
+    response = client.json.post(url, json.dumps(data))
+
+    assert response.status_code == 400
+    assert "The user must be a valid contact" in response.data["username"][0]
+
+
+def test_create_member_using_username_being_contacts(client):
+    project = f.ProjectFactory()
+    john = f.UserFactory.create()
+    joseph = f.UserFactory.create()
+    tester = f.RoleFactory(project=project, name="Tester", permissions=["view_project"])
+    f.MembershipFactory(project=project, user=john, role=tester, is_admin=True)
+
+    # They are members from another project
+    project2 = f.ProjectFactory()
+    gamer = f.RoleFactory(project=project2, name="Gamer", permissions=["view_project"])
+    f.MembershipFactory(project=project2, user=john, role=gamer, is_admin=True)
+    f.MembershipFactory(project=project2, user=joseph, role=gamer)
+
+    url = reverse("memberships-list")
+
+    data = {"project": project.id, "role": tester.pk, "username": joseph.username}
+    client.login(john)
+    response = client.json.post(url, json.dumps(data))
+
+    assert response.status_code == 201
+    assert response.data["user"] == joseph.id
+
+
 def test_create_members_in_bulk():
     with mock.patch("taiga.projects.services.members.db") as db:
-        data = [{"role_id": "1", "email": "member1@email.com"},
-                {"role_id": "1", "email": "member2@email.com"}]
+        data = [{"role_id": "1", "username": "member1@email.com"},
+                {"role_id": "1", "username": "member2@email.com"}]
         members = services.create_members_in_bulk(data, project_id=1)
         db.save_in_bulk.assert_called_once_with(members, None, None)
 
@@ -51,25 +106,57 @@ def test_api_create_bulk_members(client):
     project = f.ProjectFactory()
     john = f.UserFactory.create()
     joseph = f.UserFactory.create()
-    tester = f.RoleFactory(project=project, name="Tester")
-    gamer = f.RoleFactory(project=project, name="Gamer")
-    f.MembershipFactory(project=project, user=project.owner, is_admin=True)
+    other = f.UserFactory.create()
+    tester = f.RoleFactory(project=project, name="Tester", permissions=["view_project"])
+    gamer = f.RoleFactory(project=project, name="Gamer", permissions=["view_project"])
+    f.MembershipFactory(project=project, user=john, role=tester, is_admin=True)
+
+    # John and Other are members from another project
+    project2 = f.ProjectFactory()
+    f.MembershipFactory(project=project2, user=john, role=gamer, is_admin=True)
+    f.MembershipFactory(project=project2, user=other, role=gamer)
 
     url = reverse("memberships-bulk-create")
 
     data = {
         "project_id": project.id,
         "bulk_memberships": [
-            {"role_id": tester.pk, "email": john.email},
-            {"role_id": gamer.pk, "email": joseph.email},
+            {"role_id": gamer.pk, "username": joseph.email},
+            {"role_id": gamer.pk, "username": other.username},
         ]
     }
-    client.login(project.owner)
+    client.login(john)
     response = client.json.post(url, json.dumps(data))
 
     assert response.status_code == 200
-    assert response.data[0]["email"] == john.email
-    assert response.data[1]["email"] == joseph.email
+    response_user_ids = set([u["user"] for u in response.data])
+    user_ids = {other.id, joseph.id}
+    assert(user_ids.issubset(response_user_ids))
+
+
+def test_api_create_bulk_members_invalid_user_id(client):
+    project = f.ProjectFactory()
+    john = f.UserFactory.create()
+    joseph = f.UserFactory.create()
+    other = f.UserFactory.create()
+    tester = f.RoleFactory(project=project, name="Tester", permissions=["view_project"])
+    gamer = f.RoleFactory(project=project, name="Gamer", permissions=["view_project"])
+    f.MembershipFactory(project=project, user=john, role=tester, is_admin=True)
+
+    url = reverse("memberships-bulk-create")
+
+    data = {
+        "project_id": project.id,
+        "bulk_memberships": [
+            {"role_id": gamer.pk, "username": joseph.email},
+            {"role_id": gamer.pk, "username": other.username},
+        ]
+    }
+    client.login(john)
+    response = client.json.post(url, json.dumps(data))
+
+    assert response.status_code == 400
+    test_api_create_bulk_members_invalid_user_id
 
 
 def test_api_create_bulk_members_with_invalid_roles(client):
@@ -85,8 +172,8 @@ def test_api_create_bulk_members_with_invalid_roles(client):
     data = {
         "project_id": project.id,
         "bulk_memberships": [
-            {"role_id": tester.pk, "email": john.email},
-            {"role_id": gamer.pk, "email": joseph.email},
+            {"role_id": tester.pk, "username": john.email},
+            {"role_id": gamer.pk, "username": joseph.email},
         ]
     }
     client.login(project.owner)
@@ -109,8 +196,8 @@ def test_api_create_bulk_members_with_allowed_domain(client):
     data = {
         "project_id": project.id,
         "bulk_memberships": [
-            {"role_id": tester.pk, "email": "test1@email.com"},
-            {"role_id": gamer.pk, "email": "test2@email.com"},
+            {"role_id": tester.pk, "username": "test1@email.com"},
+            {"role_id": gamer.pk, "username": "test2@email.com"},
         ]
     }
     client.login(project.owner)
@@ -133,16 +220,17 @@ def test_api_create_bulk_members_with_allowed_and_unallowed_domain(client, setti
     data = {
         "project_id": project.id,
         "bulk_memberships": [
-            {"role_id": tester.pk, "email": "test@invalid-domain.com"},
-            {"role_id": gamer.pk, "email": "test@email.com"},
+            {"role_id": tester.pk, "username": "test@invalid-domain.com"},
+            {"role_id": gamer.pk, "username": "test@email.com"},
         ]
     }
     client.login(project.owner)
     response = client.json.post(url, json.dumps(data))
 
+    print(response.data)
     assert response.status_code == 400
-    assert "email" in response.data["bulk_memberships"][0]
-    assert "email" not in response.data["bulk_memberships"][1]
+    assert "username" in response.data["bulk_memberships"][0]
+    assert "username" not in response.data["bulk_memberships"][1]
 
 
 def test_api_create_bulk_members_with_unallowed_domains(client, settings):
@@ -157,16 +245,16 @@ def test_api_create_bulk_members_with_unallowed_domains(client, settings):
     data = {
         "project_id": project.id,
         "bulk_memberships": [
-            {"role_id": tester.pk, "email": "test1@invalid-domain.com"},
-            {"role_id": gamer.pk, "email": "test2@invalid-domain.com"},
+            {"role_id": tester.pk, "username": "test1@invalid-domain.com"},
+            {"role_id": gamer.pk, "username": "test2@invalid-domain.com"},
         ]
     }
     client.login(project.owner)
     response = client.json.post(url, json.dumps(data))
 
     assert response.status_code == 400
-    assert "email" in response.data["bulk_memberships"][0]
-    assert "email" in response.data["bulk_memberships"][1]
+    assert "username" in response.data["bulk_memberships"][0]
+    assert "username" in response.data["bulk_memberships"][1]
 
 
 def test_api_create_bulk_members_without_enough_memberships_private_project_slots_one_project(client):
@@ -180,10 +268,10 @@ def test_api_create_bulk_members_without_enough_memberships_private_project_slot
     data = {
         "project_id": project.id,
         "bulk_memberships": [
-            {"role_id": role.pk, "email": "test1@test.com"},
-            {"role_id": role.pk, "email": "test2@test.com"},
-            {"role_id": role.pk, "email": "test3@test.com"},
-            {"role_id": role.pk, "email": "test4@test.com"},
+            {"role_id": role.pk, "username": "test1@test.com"},
+            {"role_id": role.pk, "username": "test2@test.com"},
+            {"role_id": role.pk, "username": "test3@test.com"},
+            {"role_id": role.pk, "username": "test4@test.com"},
         ]
     }
     client.login(user)
@@ -206,10 +294,10 @@ def test_api_create_bulk_members_for_admin_without_enough_memberships_private_pr
     data = {
         "project_id": project.id,
         "bulk_memberships": [
-            {"role_id": role.pk, "email": "test1@test.com"},
-            {"role_id": role.pk, "email": "test2@test.com"},
-            {"role_id": role.pk, "email": "test3@test.com"},
-            {"role_id": role.pk, "email": "test4@test.com"},
+            {"role_id": role.pk, "username": "test1@test.com"},
+            {"role_id": role.pk, "username": "test2@test.com"},
+            {"role_id": role.pk, "username": "test3@test.com"},
+            {"role_id": role.pk, "username": "test4@test.com"},
         ]
     }
     client.login(user)
@@ -237,10 +325,10 @@ def test_api_create_bulk_members_with_enough_memberships_private_project_slots_m
     data = {
         "project_id": project.id,
         "bulk_memberships": [
-            {"role_id": role.pk, "email": "test1@test.com"},
-            {"role_id": role.pk, "email": "test2@test.com"},
-            {"role_id": role.pk, "email": "test3@test.com"},
-            {"role_id": role.pk, "email": "test4@test.com"},
+            {"role_id": role.pk, "username": "test1@test.com"},
+            {"role_id": role.pk, "username": "test2@test.com"},
+            {"role_id": role.pk, "username": "test3@test.com"},
+            {"role_id": role.pk, "username": "test4@test.com"},
         ]
     }
     client.login(user)
@@ -260,10 +348,10 @@ def test_api_create_bulk_members_without_enough_memberships_public_project_slots
     data = {
         "project_id": project.id,
         "bulk_memberships": [
-            {"role_id": role.pk, "email": "test1@test.com"},
-            {"role_id": role.pk, "email": "test2@test.com"},
-            {"role_id": role.pk, "email": "test3@test.com"},
-            {"role_id": role.pk, "email": "test4@test.com"},
+            {"role_id": role.pk, "username": "test1@test.com"},
+            {"role_id": role.pk, "username": "test2@test.com"},
+            {"role_id": role.pk, "username": "test3@test.com"},
+            {"role_id": role.pk, "username": "test4@test.com"},
         ]
     }
     client.login(user)
@@ -290,10 +378,10 @@ def test_api_create_bulk_members_with_enough_memberships_public_project_slots_mu
     data = {
         "project_id": project.id,
         "bulk_memberships": [
-            {"role_id": role.pk, "email": "test1@test.com"},
-            {"role_id": role.pk, "email": "test2@test.com"},
-            {"role_id": role.pk, "email": "test3@test.com"},
-            {"role_id": role.pk, "email": "test4@test.com"},
+            {"role_id": role.pk, "username": "test1@test.com"},
+            {"role_id": role.pk, "username": "test2@test.com"},
+            {"role_id": role.pk, "username": "test3@test.com"},
+            {"role_id": role.pk, "username": "test4@test.com"},
         ]
     }
     client.login(user)
@@ -312,7 +400,7 @@ def test_api_create_bulk_members_with_extra_text(client, outbox):
     data = {
         "project_id": project.id,
         "bulk_memberships": [
-            {"role_id": tester.pk, "email": "john@email.com"},
+            {"role_id": tester.pk, "username": "john@email.com"},
         ],
         "invitation_extra_text": invitation_extra_text
     }
@@ -350,7 +438,7 @@ def test_api_invite_existing_user(client, outbox):
     client.login(role.project.owner)
 
     url = reverse("memberships-list")
-    data = {"role": role.pk, "project": role.project.pk, "email": user.email}
+    data = {"role": role.pk, "project": role.project.pk, "username": user.email}
 
     response = client.json.post(url, json.dumps(data))
 
@@ -364,7 +452,7 @@ def test_api_invite_existing_user(client, outbox):
     assert "Added to the project" in message.subject
 
 
-def test_api_create_invalid_membership_email_failing(client):
+def test_api_create_invalid_membership_no_email_no_user(client):
     "Should not create the invitation linked to that user"
     user = f.UserFactory.create()
     role = f.RoleFactory.create()
@@ -388,7 +476,7 @@ def test_api_create_invalid_membership_role_doesnt_exist_in_the_project(client):
     client.login(project.owner)
 
     url = reverse("memberships-list")
-    data = {"role": role.pk, "project": project.pk, "email": user.email}
+    data = {"role": role.pk, "project": project.pk, "username": user.email}
 
     response = client.json.post(url, json.dumps(data))
 
@@ -404,7 +492,7 @@ def test_api_create_membership(client):
 
     client.login(membership.user)
     url = reverse("memberships-list")
-    data = {"role": role.pk, "project": role.project.pk, "email": user.email}
+    data = {"role": role.pk, "project": role.project.pk, "username": user.email}
     response = client.json.post(url, json.dumps(data))
 
     assert response.status_code == 201
@@ -419,11 +507,11 @@ def test_api_create_membership_with_unallowed_domain(client, settings):
 
     client.login(membership.user)
     url = reverse("memberships-list")
-    data = {"role": role.pk, "project": role.project.pk, "email": "test@invalid-email.com"}
+    data = {"role": role.pk, "project": role.project.pk, "username": "test@invalid-email.com"}
     response = client.json.post(url, json.dumps(data))
 
     assert response.status_code == 400
-    assert "email" in response.data
+    assert "username" in response.data
 
 
 def test_api_create_membership_with_allowed_domain(client, settings):
@@ -434,7 +522,7 @@ def test_api_create_membership_with_allowed_domain(client, settings):
 
     client.login(membership.user)
     url = reverse("memberships-list")
-    data = {"role": role.pk, "project": role.project.pk, "email": "test@email.com"}
+    data = {"role": role.pk, "project": role.project.pk, "username": "test@email.com"}
     response = client.json.post(url, json.dumps(data))
 
     assert response.status_code == 201
@@ -449,7 +537,7 @@ def test_api_create_membership_without_enough_memberships_private_project_slots_
 
     client.login(user)
     url = reverse("memberships-list")
-    data = {"role": role.pk, "project": project.pk, "email": "test@test.com"}
+    data = {"role": role.pk, "project": project.pk, "username": "test@test.com"}
     response = client.json.post(url, json.dumps(data))
 
     assert response.status_code == 400
@@ -470,7 +558,7 @@ def test_api_create_membership_with_enough_memberships_private_project_slots_mul
 
     client.login(user)
     url = reverse("memberships-list")
-    data = {"role": role.pk, "project": project.pk, "email": "test@test.com"}
+    data = {"role": role.pk, "project": project.pk, "username": "test@test.com"}
     response = client.json.post(url, json.dumps(data))
 
     assert response.status_code == 201
@@ -484,7 +572,7 @@ def test_api_create_membership_without_enough_memberships_public_project_slots_o
 
     client.login(user)
     url = reverse("memberships-list")
-    data = {"role": role.pk, "project": project.pk, "email": "test@test.com"}
+    data = {"role": role.pk, "project": project.pk, "username": "test@test.com"}
     response = client.json.post(url, json.dumps(data))
 
     assert response.status_code == 400
@@ -505,7 +593,7 @@ def test_api_create_membership_with_enough_memberships_public_project_slots_mult
 
     client.login(user)
     url = reverse("memberships-list")
-    data = {"role": role.pk, "project": project.pk, "email": "test@test.com"}
+    data = {"role": role.pk, "project": project.pk, "username": "test@test.com"}
     response = client.json.post(url, json.dumps(data))
 
     assert response.status_code == 201
@@ -515,11 +603,20 @@ def test_api_edit_membership(client):
     membership = f.MembershipFactory(is_admin=True)
     client.login(membership.user)
     url = reverse("memberships-detail", args=[membership.id])
-    data = {"email": "new@email.com"}
+    data = {"username": "new@email.com"}
     response = client.json.patch(url, json.dumps(data))
-
     assert response.status_code == 200
 
+
+def test_api_edit_membership(client):
+    membership = f.MembershipFactory(is_admin=True)
+    client.login(membership.user)
+    url = reverse("memberships-detail", args=[membership.id])
+    data = {"username": "new@email.com"}
+    response = client.json.patch(url, json.dumps(data))
+    assert response.status_code == 200
+
+
 def test_api_change_owner_membership_to_no_admin_return_error(client):
     project = f.ProjectFactory()
     membership_owner = f.MembershipFactory(project=project, user=project.owner, is_admin=True)