CODEWITHSUNDEEP
dartflutterjson-deserialization
walker
walker

Reputation: 767

built_value deserialize got error " type '_InternalLinkedHashMap<String, dynamic>' is not a subtype of type 'Iterable<dynamic>' in type cast"

my model:

abstract class Post implements Built<Post, PostBuilder> {
    static Serializer<Post> get serializer => _$postSerializer;
    int get userId;
    int get id;
    String get title;
    String get body;
    factory Post([updates(PostBuilder b)]) = _$Post;
    Post._();
}

my reqest:

Future<Post> getPostById(int id) async {
    final resp = await http.get('https://jsonplaceholder.typicode.com/posts/${id}');  
    if(resp.statusCode == 200) {
        return serializers.deserializeWith(Post.serializer, json.decode(resp.body));
    }else {
        throw Exception('Failed to load post');
    }
}

and the breakpoint in source code at:

 if (serializer is StructuredSerializer) {
    try {
      // ===> HERE
      return serializer.deserialize(this, object as Iterable,
          specifiedType: specifiedType);
    } on Error catch (error) {
      throw new DeserializationError(object, specifiedType, error);
    }

 }else if(serializer is PrimitiveSerializer) {
     //...
 }

the Error:

Exception has occurred. Deserializing '{userId: 1, id: 3, title: ea molestias quasi exercitationem repellat qui ipsa...' to 'Post' failed due to: type '_InternalLinkedHashMap' is not a subtype of type 'Iterable' in type cast

my question is where I'm wrong with the type definition or deserialization usage, and, I got a single object in response.body(a Map), why the code exectue at as Iterable but not PrimitiveSerializer directive.

Upvotes: 1

Views: 2363

Answers (1)

walker
walker

Reputation: 767

the key is StandardJsonPlugin.

I copied the serializers.dart file from official example:

@SerializersFor(const [
  Account,
  Cat,
  CompoundValue,
  Fish,
  GenericValue,
  SimpleValue,
  VerySimpleValue,
])
final Serializers serializers = _$serializers; // see this line

but when I look up in the network, people use this:

final Serializers serializers = 
    (
      _$serializers.toBuilder()
      ..addPlugin(StandardJsonPlugin())
    ).build();

and sure it works for me either, when I add the StandardJsonPlugin.

Upvotes: 6

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