docs: Add guide for managing user profile photos (#3280)

docs/06-concepts/11-authentication/03-working-with-users.md

@@ -151,6 +151,8 @@ This returns a `UserProfileModel` object containing the logged-in user's profile
 
 ### Extending the user profile edit endpoint
 
+For a step-by-step guide covering upload, display, validation, and storage, see [Manage user profile photos](./profile-photos).
+
 The authentication module provides a `UserProfileEditBaseEndpoint` abstract class that you can extend to expose user profile editing functionality to your app. This base endpoint includes methods for:
 
 - Removing user images

docs/06-concepts/11-authentication/07-profile-photos.md

@@ -0,0 +1,301 @@
+---
+sidebar_label: Profile photos
+description: Upload, update, and display user profile photos with Serverpod's auth module, including server setup, Flutter client code, and storage configuration.
+---
+
+# Manage user profile photos
+
+Add profile photo upload and display to your Serverpod app using the authentication module's built-in image handling. When you're done, signed-in users can upload a photo from Flutter, and your app displays it from a public URL.
+
+Profile photos are stored in **public** storage, square-cropped and resized on the server, and exposed as a public HTTP URL on `UserProfileModel.imageUrl`. The auth module registers a read-only `userProfileInfo` endpoint by default; you expose upload methods yourself.
+
+## Before you start
+
+- [Authentication is set up](./setup) and users can sign in.
+- Users have a `UserProfile` (created automatically by most identity providers on first sign-in).
+- You have run `serverpod generate` at least once.
+
+For the upload UI, add these Flutter dependencies:
+
+```yaml title="pubspec.yaml"
+dependencies:
+  image_picker: ^1.0.0
+  image: ^4.0.15
+  file_picker: '>=8.1.0 <11.0.0'  # web
+  image_cropper: '>=7.0.0 <13.0.0'  # mobile, optional
+```
+
+## Expose the profile edit endpoint
+
+The auth module registers `userProfileInfo` (read-only `get()`). Upload methods live on `UserProfileEditBaseEndpoint`, which you must expose on your server.
+
+Create a concrete endpoint:
+
+```dart title="lib/src/endpoints/user_profile_endpoint.dart"
+import 'package:serverpod/serverpod.dart';
+import 'package:serverpod_auth_idp_server/core.dart';
+
+/// Endpoint to view and edit the signed-in user's profile.
+class UserProfileEndpoint extends UserProfileEditBaseEndpoint {}
+```
+
+Run `serverpod generate`. Your Flutter client exposes methods on `client.userProfile` (the accessor matches your endpoint class name):
+
+| Method | Returns | Auth required |
+| ------ | ------- | ------------- |
+| `get()` | `UserProfileModel` | Yes |
+| `setUserImage(ByteData image)` | `UserProfileModel` | Yes |
+| `removeUserImage()` | `UserProfileModel` | Yes |
+| `changeUserName(String? userName)` | `UserProfileModel` | Yes |
+| `changeFullName(String? fullName)` | `UserProfileModel` | Yes |
+
+```dart
+final profile = await client.userProfile.setUserImage(byteData);
+print(profile.imageUrl); // Uri?, the public URL of the new image
+```
+
+To fetch the profile without exposing edit methods, use the module endpoint:
+
+```dart
+final profile = await client.modules.serverpod_auth_core.userProfileInfo.get();
+```
+
+### Restrict who can edit
+
+There is no built-in `userCanEditUserImage` flag in `serverpod_auth_idp` (legacy `serverpod_auth` had this). Override the endpoint to restrict uploads:
+
+```dart
+class UserProfileEndpoint extends UserProfileEditBaseEndpoint {
+  @override
+  Future<UserProfileModel> setUserImage(Session session, ByteData image) async {
+    if (!session.authenticated!.scopes.contains(MyScope.canEditProfile)) {
+      throw MyForbiddenException();
+    }
+    return super.setUserImage(session, image);
+  }
+}
+```
+
+## Upload a profile photo from Flutter
+
+There is no built-in upload widget in the authentication module. Pick an image on the client, convert it to `ByteData`, and pass it to `setUserImage`.
+
+The server decodes the image, crops it to a square, resizes it, and stores it. The format you send does not affect the stored format.
+
+```dart
+import 'dart:typed_data';
+
+import 'package:file_picker/file_picker.dart';
+import 'package:flutter/foundation.dart';
+import 'package:image/image.dart' as img;
+import 'package:image_picker/image_picker.dart';
+
+/// Picks an image, optionally resizes it, and returns [ByteData] for upload.
+/// The server crops to square and resizes again. Client-side prep is for UX and bandwidth.
+Future<ByteData?> pickProfileImageBytes({int maxSize = 512}) async {
+  Uint8List? rawBytes;
+
+  if (kIsWeb) {
+    final result = await FilePicker.platform.pickFiles(
+      type: FileType.custom,
+      allowedExtensions: ['jpg', 'jpeg', 'png'],
+    );
+    rawBytes = result?.files.first.bytes;
+  } else {
+    final picked = await ImagePicker().pickImage(source: ImageSource.gallery);
+    if (picked != null) rawBytes = await picked.readAsBytes();
+  }
+
+  if (rawBytes == null) return null;
+
+  final decoded = img.decodeImage(rawBytes);
+  if (decoded == null) return null; // invalid image; show an error to the user
+
+  final resized = decoded.width > maxSize || decoded.height > maxSize
+      ? img.copyResizeCropSquare(decoded, size: maxSize)
+      : decoded;
+
+  final encoded = img.encodePng(resized);
+  return ByteData.view(Uint8List.fromList(encoded).buffer);
+}
+```
+
+Call the endpoint after picking:
+
+```dart
+Future<UserProfileModel?> uploadProfilePhoto(Client client) async {
+  final bytes = await pickProfileImageBytes();
+  if (bytes == null) return null;
+  return client.userProfile.setUserImage(bytes);
+}
+```
+
+On iOS and Android, use `image_cropper` with a circular crop before upload for better UX. Cropping is not available on web with this pattern.
+
+### Error handling
+
+| Failure | What happens |
+| ------- | ------------ |
+| User not signed in | `ServerpodUnauthenticatedException` |
+| No profile exists | `UserProfileNotFoundException` |
+| Invalid or corrupt image bytes | Server throws when image decode fails |
+| User cancels picker | Return `null` on the client; no server call |
+
+## Display the profile photo
+
+The `UserProfileModel.imageUrl` field is a public `Uri?`. When it is `null`, show a placeholder.
+
+```dart
+final profile = await client.userProfile.get();
+// Or: await client.modules.serverpod_auth_core.userProfileInfo.get();
+
+final imageUrl = profile?.imageUrl?.toString();
+
+CircleAvatar(
+  backgroundImage: imageUrl != null ? NetworkImage(imageUrl) : null,
+  child: imageUrl == null ? const Icon(Icons.person) : null,
+)
+```
+
+For caching, use `cached_network_image` or `extended_image`.
+
+The `imageUrl` field is public. If you fetch another user's `UserProfileModel` from your own endpoint, display `imageUrl` the same way. Only upload endpoints are scoped to the signed-in user.
+
+## Remove or replace a photo
+
+Remove the photo (`imageUrl` becomes `null`):
+
+```dart
+final profile = await client.userProfile.removeUserImage();
+```
+
+Unlike [legacy serverpod_auth](./legacy/working-with-users), removing a photo does **not** restore a generated default avatar. Show a placeholder in your UI, or call `setDefaultUserImage` on signup (see below).
+
+Replace a photo by calling `setUserImage` again with new bytes. The server creates a new stored file with a new random suffix.
+
+## Configure image size and format
+
+Pass `UserProfileConfig` to `initializeAuthServices` in `server.dart`:
+
+| Setting | Default | Description |
+| ------- | ------- | ----------- |
+| `userImageSize` | `256` | Output width and height in pixels (square) |
+| `userImageFormat` | `UserProfileImageType.jpg` | Stored format (`.jpg` or `.png`) |
+| `userImageQuality` | `70` | JPG quality (ignored for PNG) |
+| `userImageGenerator` | `defaultUserImageGenerator` | Used by `setDefaultUserImage()` |
+| `imageFetchFunc` | `http.get` | Used when importing from a URL (social sign-in) |
+
+```dart
+pod.initializeAuthServices(
+  userProfileConfig: UserProfileConfig(
+    userImageSize: 512,
+    userImageFormat: UserProfileImageType.png,
+    userImageQuality: 85,
+    userImageGenerator: defaultUserImageGenerator,
+    onAfterUserProfileCreated: (session, profile, {required transaction}) async {
+      await AuthServices.instance.userProfiles.setDefaultUserImage(
+        session,
+        profile.authUserId,
+        transaction: transaction,
+      );
+    },
+  ),
+  identityProviderBuilders: [...],
+  tokenManagerBuilders: [...],
+);
+```
+
+The `defaultUserImageGenerator` function produces a colored circle with the first letter of the user name.
+
+The server automatically validates and optimizes uploads: it decodes bytes (must be a valid image), square-crops to `userImageSize`, re-encodes as JPG or PNG per config, and stores the file in public storage.
+
+Recommended client-side checks (not enforced by the server):
+
+- Allow only JPG and PNG extensions.
+- Reject files over roughly 5 to 10 MB before upload.
+- Verify `decodeImage` succeeds before calling `setUserImage`.
+
+Google and similar providers automatically import a profile photo on first sign-in when the provider returns one and the user has no image yet.
+
+## Configure storage for production
+
+In development, profile images use the default database-backed public storage. No extra setup is required.
+
+Public URLs look like:
+
+```text
+http://localhost:8080/serverpod_cloud_storage?method=file&path=serverpod/user_images/{authUserId}-{id}.jpg
+```
+
+Set `publicHost`, `publicPort`, and `publicScheme` in `config/development.yaml` to match how clients reach your API server.
+
+For production, configure object storage (S3, GCP, or R2) for `storageId: 'public'`. See [Uploading files](../file-uploads). Profile images require publicly accessible URLs because clients load them directly over HTTP.
+
+## Use server-side APIs for custom logic
+
+In endpoints or callbacks, use `AuthServices.instance.userProfiles`:
+
+```dart
+import 'package:serverpod_auth_idp_server/core.dart';
+
+// Set from bytes (same as the endpoint)
+await AuthServices.instance.userProfiles.setUserImageFromBytes(
+  session, authUserId, imageBytes,
+);
+
+// Import from a URL (e.g. after OAuth)
+await AuthServices.instance.userProfiles.setUserImageFromUrl(
+  session, authUserId, Uri.parse('https://example.com/photo.jpg'),
+);
+
+// Generate and store a default avatar
+await AuthServices.instance.userProfiles.setDefaultUserImage(session, authUserId);
+
+// Remove image
+await AuthServices.instance.userProfiles.removeUserImage(session, authUserId);
+
+// Read profile in any endpoint
+final profile = await session.authenticated!.userProfile(session);
+```
+
+## Verify
+
+1. Sign in to your app.
+2. Call `client.userProfile.setUserImage(byteData)` with a test PNG or JPG.
+3. Confirm the returned `imageUrl` is non-null and starts with your server's public host.
+4. Open `imageUrl` in a browser. The image loads.
+5. Confirm your UI updates after upload.
+6. Call `removeUserImage()`. `imageUrl` becomes `null` and your placeholder appears.
+
+## Troubleshooting
+
+### `setUserImage` is missing on the client
+
+Create `UserProfileEndpoint extends UserProfileEditBaseEndpoint` and run `serverpod generate`.
+
+### `UserProfileNotFoundException`
+
+The signed-in user has no profile yet. Ensure your identity provider creates one on first sign-in.
+
+### Image URL does not load
+
+Check `publicHost`, `publicPort`, and `publicScheme` in your server config match how clients reach the API server.
+
+### Invalid image error
+
+The bytes are corrupt or not an image. Validate with `decodeImage` on the client before upload.
+
+### Image looks low quality
+
+Default JPG quality is 70. Raise `userImageQuality` or use PNG format in `UserProfileConfig`.
+
+### Web upload fails silently
+
+The `file_picker` package may return null bytes. Ensure you read bytes correctly from the picked file.
+
+## Related
+
+- [Working with users](./working-with-users): profiles, names, and the edit endpoint overview
+- [Authentication setup](./setup): initial auth module configuration
+- [Uploading files](../file-uploads): cloud storage for production
+- [Legacy: displaying or editing user images](./legacy/working-with-users): legacy `serverpod_auth` widgets