cache readFragment return null

[sahmadreza]

I try to use readFragment to get the PostFragment by id but it always returns null

Show example

 final client = GetIt.I<Client>();
 GAllPostReq request = GAllPostReq((b) => b..requestId = "posts"..vars.userId= "47244640263");

@override
  Widget build(BuildContext context) {
    super.build(context);
    return Operation(
        client: client,
        operationRequest: request,
        builder: (BuildContext context, OperationResponse<GAllPostData, GAllPostVars>? response, Object? error) {
          if (response == null || response.loading) return const PostLoader();
          final posts = response.data?.explore.edges ?? BuiltList();

          return ListView.builder(
            itemCount: posts.length,
            itemBuilder: (context, index) {
              debugPrint("cache identify:  ${client.cache.identify(posts[index]?.node)}");
              debugPrint("store get:  ${client.cache.store.get(client.cache.identify(posts[index])!)}");
              debugPrint("readFragment:  ${client.cache.readFragment(GPostFragmentReq(
                    (b) => b..idFields = {"id": posts[index]?.node?.id},
              ))}");
              debugPrint("cache keys:  ${client.cache.store.keys}");

              return const SizedBox();
            },
          );
        });
  }

Debug results:

readFragment:

null

cache identify:

Post:21474836490

store get:

{__typename: Post, id: 21474836490, slug: Usiay5vmwqQ, file: {$ref: File:4294967296}, favoritedUsers({"where":{"id":"47244640263"}}): {__typename: UserConnection, totalCount: 0}, likedUsers({"where":{"id":"47244640263"}}): {__typename: UserConnection, totalCount: 0}, owner: {$ref: User:47244640257}, tags: [{$ref: Tag:42949672960}, {$ref: Tag:42949672961}, {$ref: Tag:42949672962}, {$ref: Tag:42949672963}]}

cache keys:

[File:4294967296, File:4294967297, File:4294967298, Post:21474836480, Post:21474836490,  Tag:42949672964, User:47244640256, User:47244640257, UserProfile:47244640263]

Show ferry client

  final box = await Hive.openBox<Map<String, dynamic>>("graphql");
  await box.clear();
  
  final client = Client(
    defaultFetchPolicies: {OperationType.query: FetchPolicy.CacheAndNetwork},
    link: HttpLink(graphQLUrl),
    cache: Cache(store: HiveStore(box)),
  );

  GetIt.I.registerLazySingleton<Client>(() => client);

Show GraphQL Query

# import '../fragments/post_fragment.graphql'

query AllPost ( $userId: ID) {
    posts {
        pageInfo {
            hasNextPage
            hasPreviousPage
            endCursor
            startCursor
        }
        totalCount
        edges {
            cursor
            node {
              ...PostFragment
            }
        }
    }
}

Show GraphQL Fragments

fragment PostFragment on Post {
    id
    slug
    isFavorited: favoritedUsers(where: {id: $userId}){
        totalCount
    }
    isLiked: likedUsers(where: {id: $userId}){
        totalCount
    }
    file {
        ...File
    }
    owner {
        ...Person
    }
    tags {
        ...Tag
    }
}

fragment Tag on Tag {
    id
    name
    slug
    type
}

fragment Person on User {
    id
    avatarUrl
    username
     image {
        ...File
    }
}

fragment File on File {
    id
    smallSize
    thumbnail
    largeSize
}

Dependencies

dependencies:
  hive: ^2.2.3
  hive_flutter: ^1.1.0
  ferry: ^0.13.0
  ferry_flutter: ^0.8.0-dev.7
  ferry_hive_store: ^0.5.1-dev.1
  gql_http_link: ^0.4.6-alpha+1672756470520
  gql_code_builder: ^0.7.1-alpha+1672756470533
  get_it: ^7.2.0

dev_dependencies:
  build_runner: ^2.3.2
  ferry_generator: ^0.7.0-dev.0
  hive_generator: ^2.0.0

[sahmadreza]

The problem is the use of variable in the fragment.

fragment PostFragment on Post {
   // ...
    isFavorited: favoritedUsers(where: {id: $userId}){
        totalCount
    }
    isLiked: likedUsers(where: {id: $userId}){
        totalCount
    }
   // ...
}

For this reason, readFragment cannot get the post fragment from the cache and returns null

[knaeckeKami]

I think you need to pass the variables used in the fragment (userId) also to the fragment request

[sahmadreza]

I think you need to pass the variables used in the fragment (userId) also to the fragment request

Yes, but GPostFragmentReq has no generated vars for userId

I can just pass idFields

client.cache.readFragment(GPostFragmentReq(
                    (b) => b..idFields = {"id": posts[index]?.node?.id},
              ))

[knaeckeKami]

I see. This sound like a bug.

I'll look into it.

readFragment is just a thin layer above denormalizeFragment though.
Does it work if you call denormalizeFragment directly, like this:

extension MyReadFragment on Cache {

 /// Reads denormalized data from the Cache for the given fragment.
  TData? readFragment2<TData, TVars>(
    FragmentRequest<TData, TVars> request, {
    bool optimistic = true,
    Map<String, dynamic> variables = {}
  }) {
    final json = denormalizeFragment(
      read: optimistic ? optimisticReader : (dataId) => store.get(dataId),
      document: request.document,
      idFields: request.idFields,
      fragmentName: request.fragmentName,
      // this is custom
      variables: variables,
      typePolicies: typePolicies,
      addTypename: addTypename,
      dataIdFromObject: dataIdFromObject,
      possibleTypes: possibleTypes,
    );
    return json == null ? null : request.parseData(json);
  }


}

?

[sahmadreza]

@knaeckeKami

readFragment is just a thin layer above denormalizeFragment though.
Does it work if you call denormalizeFragment directly, like this:

Yes, it's working. 👍

[sahmadreza]

@knaeckeKami

how can use this extension in CacheProxy?

[knaeckeKami]

You'll probably have to access to cache directly through some other means (like setting it as global variable or something like this) and bypass the cache proxy as workaround until this is fixed properly in ferry

[sahmadreza]

OK, thanks for your help

[knaeckeKami]

This should be fixed in gql_code_builder: 0.7.1-alpha+1676138216360.

I added a fragment similar to yours: https://github.com/gql-dart/gql/pull/382/files#diff-86124cb045d0e2d1f35d90d940bfe72821613a8ca4999a43bcc9615aab57c719

and verified that now the variable userId is properly included: https://github.com/gql-dart/gql/pull/382/files#diff-0053d21550d6ab52170d9f97f8b74fadf9fd1d7da1b5357d6742bc854ed70d05R30.

Could you add this gql_code_builder: 0.7.1-alpha+1676138216360 via dependency_override and see if this works for you?

[sahmadreza]

Very good, yes, I will definitely check it, but it seems to be fixed