Reference project members by id instead of user_id.

app/controllers/projects/project_members_controller.rb

@@ -41,12 +41,12 @@ class Projects::ProjectMembersController < Projects::ApplicationController
   end
 
   def update
-    @project_member = @project.project_members.find_by(user_id: member)
+    @project_member = @project.project_members.find(params[:id])
     @project_member.update_attributes(member_params)
   end
 
   def destroy
-    @project_member = @project.project_members.find_by(user_id: member)
+    @project_member = @project.project_members.find(params[:id])
     @project_member.destroy
 
     respond_to do |format|
@@ -78,10 +78,6 @@ class Projects::ProjectMembersController < Projects::ApplicationController
 
   protected
 
-  def member
-    @member ||= User.find_by(username: params[:id])
-  end
-
   def member_params
     params.require(:project_member).permit(:user_id, :access_level)
   end

app/views/admin/projects/show.html.haml

@@ -131,7 +131,7 @@
                 %span.light Owner
               - else
                 %span.light= project_member.human_access
-                = link_to namespace_project_project_member_path(@project.namespace, @project, user), data: { confirm: remove_from_project_team_message(@project, user)}, method: :delete, remote: true, class: "btn btn-sm btn-remove" do
+                = link_to namespace_project_project_member_path(@project.namespace, @project, project_member), data: { confirm: remove_from_project_team_message(@project, user)}, method: :delete, remote: true, class: "btn btn-sm btn-remove" do
                   %i.fa.fa-times
       .panel-footer
         = paginate @project_members, param_name: 'project_members_page', theme: 'gitlab'

app/views/projects/project_members/_project_member.html.haml

@@ -25,12 +25,12 @@
           = link_to leave_namespace_project_project_members_path(@project.namespace, @project), data: { confirm: "Leave project?"}, method: :delete, class: "btn-xs btn btn-remove", title: 'Leave project' do
             %i.fa.fa-minus.fa-inverse
         - else
-          = link_to namespace_project_project_member_path(@project.namespace, @project, user), data: { confirm: remove_from_project_team_message(@project, user) }, method: :delete, remote: true, class: "btn-xs btn btn-remove", title: 'Remove user from team' do
+          = link_to namespace_project_project_member_path(@project.namespace, @project, member), data: { confirm: remove_from_project_team_message(@project, user) }, method: :delete, remote: true, class: "btn-xs btn btn-remove", title: 'Remove user from team' do
             %i.fa.fa-minus.fa-inverse
 
     .edit-member.hide.js-toggle-content
       %br
-      = form_for member, as: :project_member, url: namespace_project_project_member_path(@project.namespace, @project, member.user), remote: true do |f|
+      = form_for member, as: :project_member, url: namespace_project_project_member_path(@project.namespace, @project, member), remote: true do |f|
         .prepend-top-10
           = f.select :access_level, options_for_select(ProjectMember.access_roles, member.access_level), {}, class: 'form-control'
         .prepend-top-10