Add `GetUserNameFromEmailAsync` to `IdentityUserManager`.

modules/account/src/Volo.Abp.Account.Web/Pages/Account/AccountPageModel.cs

@@ -1,7 +1,6 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
-using System.Threading.Tasks;
 using Microsoft.AspNetCore.Identity;
 using Microsoft.Extensions.Options;
 using Volo.Abp.Account.Localization;
@@ -55,22 +54,4 @@ public abstract class AccountPageModel : AbpPageModel
 
         return exception.Message;
     }
-
-    protected virtual async Task<string> GetUserNameFromEmail(string email)
-    {
-        var userName = email.Split('@')[0];
-        var existUser = await UserManager.FindByNameAsync(userName);
-        while (existUser != null)
-        {
-            var randomUserName = userName + RandomHelper.GetRandom(1000, 9999);
-            existUser = await UserManager.FindByNameAsync(randomUserName);
-            if (existUser == null)
-            {
-                userName = randomUserName;
-                break;
-            }
-        }
-
-        return userName;
-    }
 }

modules/account/src/Volo.Abp.Account.Web/Pages/Account/Register.cshtml.cs

@@ -102,7 +102,7 @@ public class RegisterModel : AccountPageModel
                 return;
             }
 
-            var userName = await GetUserNameFromEmail(emailClaim.Value);
+            var userName = await UserManager.GetUserNameFromEmailAsync(emailClaim.Value);
             Input = new PostInput { UserName = userName, EmailAddress = emailClaim.Value };
         }
     }
@@ -128,7 +128,7 @@ public class RegisterModel : AccountPageModel
                 }
                 if (Input.UserName.IsNullOrWhiteSpace())
                 {
-                    Input.UserName = await GetUserNameFromEmail(Input.EmailAddress);
+                    Input.UserName = await UserManager.GetUserNameFromEmailAsync(Input.EmailAddress);
                 }
                 await RegisterExternalUserAsync(externalLoginInfo, Input.UserName, Input.EmailAddress);
             }

modules/identity/src/Volo.Abp.Identity.Domain/Volo/Abp/Identity/IdentityUserManager.cs

@@ -436,4 +436,57 @@ public class IdentityUserManager : UserManager<IdentityUser>, IDomainService
 
         return Task.FromResult(randomUserName);
     }
+
+    public virtual async Task<string> GetUserNameFromEmailAsync(string email)
+    {
+        var userName = email.Split('@')[0];
+        if (!Options.User.AllowedUserNameCharacters.IsNullOrWhiteSpace() && !userName.All(Options.User.AllowedUserNameCharacters.Contains))
+        {
+            // The user name contains not allowed characters. We will use the email address as user name.
+            return email;
+        }
+
+        if (await ValidateUserNameAsync(userName))
+        {
+            return userName;
+        }
+
+        const int maxTryCount = 10;
+        var tryCount = 0;
+
+        if (Options.User.AllowedUserNameCharacters.IsNullOrWhiteSpace() || "0123456789".All(Options.User.AllowedUserNameCharacters.Contains))
+        {
+            var randomUserName = userName;
+            var isUserNameValid = await ValidateUserNameAsync(randomUserName);
+            while (tryCount < maxTryCount)
+            {
+                randomUserName = userName + RandomHelper.GetRandom(1000, 9999);
+                isUserNameValid = await ValidateUserNameAsync(randomUserName);
+                if (isUserNameValid)
+                {
+                    return randomUserName;
+                }
+                tryCount++;
+            }
+            if (isUserNameValid)
+            {
+                return randomUserName;
+            }
+        }
+
+        tryCount = 0;
+        while (tryCount < maxTryCount)
+        {
+            var randomUserName = userName + await GetRandomUserNameAsync(4);
+            var isUserNameValid = await ValidateUserNameAsync(randomUserName);
+            if (isUserNameValid)
+            {
+                return randomUserName;
+            }
+            tryCount++;
+        }
+
+        // We could not find a valid user name so we are returning the email address.
+        return email;
+    }
 }

modules/identity/test/Volo.Abp.Identity.Domain.Tests/Volo/Abp/Identity/IdentityUserManager_Tests.cs

@@ -5,6 +5,7 @@ using System.Security.Claims;
 using System.Text.RegularExpressions;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Identity;
+using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.Extensions.Options;
@@ -422,6 +423,34 @@ public class IdentityUserManager_Tests : AbpIdentityDomainTestBase
         username.All(c => "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-._@+".Contains(c)).ShouldBeTrue();
     }
 
+    [Fact]
+    public async Task GetUserNameFromEmailAsync()
+    {
+        _identityUserManager.Options.User.AllowedUserNameCharacters = "abcdefghijklmnopqrstuvwxyz0123456789";
+        var username = await _identityUserManager.GetUserNameFromEmailAsync("admin@abp.io");
+        username.Length.ShouldBe(9); //admin and random 4 numbers
+        username.ShouldContain("admin");
+        Regex.IsMatch(username, @"\d{4}$").ShouldBeTrue();
+
+        _identityUserManager.Options.User.AllowedUserNameCharacters = "abcdefghijklmnopqrstuvwxyz";
+        username = await _identityUserManager.GetUserNameFromEmailAsync("admin@abp.io");
+        username.Length.ShouldBe(9); //admin and random 4 characters
+        username.ShouldContain("admin");
+        Regex.IsMatch(username, @"[a-z]{4}$").ShouldBeTrue();
+
+        _identityUserManager.Options.User.AllowedUserNameCharacters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+        username = await _identityUserManager.GetUserNameFromEmailAsync("ADMIN@abp.io");
+        username.Length.ShouldBe(9); //admin and random 4 characters
+        username.ShouldContain("ADMIN");
+        Regex.IsMatch(username, @"[A-Z]{4}$").ShouldBeTrue();
+
+        _identityUserManager.Options.User.AllowedUserNameCharacters = null!;
+        username = await _identityUserManager.GetUserNameFromEmailAsync("admin@abp.io");
+        username.Length.ShouldBe(9); //admin and random 4 numbers
+        username.ShouldContain("admin");
+        Regex.IsMatch(username, @"[0-9]{4}$").ShouldBeTrue();
+    }
+
     private async Task CreateRandomDefaultRoleAsync()
     {
         await _identityRoleRepository.InsertAsync(