How can I pass a customised parameter in query?

[zhaoyi0113]

I am using graphql_flutter in a flutter app. Below is my query code:

await this.gqClient.query(QueryOptions(documentNode: gql('''
    query posts(\$size: Int, \$lastEvaluatedKey: LastEvaluatedKey){
          posts(size: \$size, lastEvaluatedKey: \$lastEvaluatedKey) {
            posts {
              id
            }
            lastEvaluatedKey {
              id
              timestamp
            }
          }
        }
      '''),
       variables: {'size': this.pageSize, 'lastEvaluatedKey': this._lastEvaluatedKey}))

I got this error when executing above code:

OperationException (GraphQL Errors:
        Validation error of type UnknownType: Unknown type LastEvaluatedKey: Undefined location)

It seems that LastEvaluatedKey is not recognised. I have declared a dart class LastEvaluatedKey as below but it doesn't seem to help. Where should I put the LastEvaluatedKey definition in the client side?

class LastEvaluatedKey {
  final String id;
  final String timestamp;

  LastEvaluatedKey({this.id, this.timestamp});
}

[RanaOsamaAsif]

Hi, the solution is to create a toJson method in your LastEvaluatedKey class and return the fields of LastEvaluatedKey in the form of Map<String, dynamic>

[zhaoyi0113]

I have updated my class as below. But it is still not working. I still get the error OperationException (GraphQL Errors: Validation error of type UnknownType: Unknown type LastEvaluatedKey: Undefined location).

class LastEvaluatedKey {
  final String id;
  final int timestamp;

  LastEvaluatedKey({this.id, this.timestamp});

  Map<String, dynamic> toJson() {
    try {
      return {
        'id': this.id,
        'timestamp': this.timestamp,
      };
    } catch (err) {
      return null;
    }
  }
}

The query code is inside gql ''' ... '''. How does it make use of class in dart code?

When I debug above code, I can see the method toJson is called and the return value seems right

[micimize]

You currently have to call _lastEvaluatedKey.toJson() yourself, as as graphql doesn't currently do any serialization

If you're going to have a lot of input types that require serialization, you can us json.encode from dart:convert:

variables: json.encode(
  variables,
  toEncodable: (dynamic object) => object.toJson(),
)

[zhaoyi0113]

Thanks for your feedback. But adding .toJson() doesn't seem to help.

await this.gqClient.query(QueryOptions(documentNode: gql('''
        query posts(\$size: Int, \$lastEvaluatedKey: LastEvaluatedKey){
          posts(size: \$size, lastEvaluatedKey: \$lastEvaluatedKey) {
            posts {
              id,
              message,
              photoPaths,
              userInfo {
                username,
                picture
              }
            }
            lastEvaluatedKey {
              id
              timestamp
            }
          }
        }
      '''), variables: {
                'size': this.pageSize,
                'lastEvaluatedKey': this._lastEvaluatedKey.toJson(),
              }));

I updated the code above but still get the same error:

OperationException (GraphQL Errors:
        Validation error of type UnknownType: Unknown type LastEvaluatedKey: Undefined location)

[micimize]

@zhaoyi0113 ohhh wait I think this error is that the graphql server doesn't recognize the type LastEvaluatedKey referenced in your query

[zhaoyi0113]

I can send query from different client so I don't think it is an issue on the server side. However, I can make it work by extracting the query parameters from LastEvlauatedKey instance like below code:

await this.gqClient.query(QueryOptions(documentNode: gql('''
        query posts(\$size: Int, \$lastKeyId: String!, \$lastKeyTimestamp: Long){
          posts(size: \$size, lastEvaluatedKey: {id: \$lastKeyId, timestamp: \$lastKeyTimestamp}) {
            posts {
              id,
              message,
              photoPaths,
              userInfo {
                username,
                picture
              }
            }
            lastEvaluatedKey {
              id
              timestamp
            }
          }
        }
      '''), variables: {
                'size': this.pageSize,
                'lastKeyId': this._lastEvaluatedKey.id,
                'lastKeyTimestamp': this._lastEvaluatedKey.timestamp,
              }));

as you can see, it takes primitive types of parameters and set them in lastEvaluatedKey.
Would you consider to support passing object instance as the parameter in future release?

[micimize]

@zhaoyi0113 hmm, I'm fairly sure there must have been some difference. The error is a GraphQL validation error: Validation error of type UnknownType: Unknown type LastEvaluatedKey, and the only place it is referenced is

        query posts(\$size: Int, \$lastEvaluatedKey: LastEvaluatedKey){

If you want to investigate it further, come to the support channel in the discord

Would you consider to support passing object instance as the parameter in future release?
nested json Maps as variables should work just fine, but better support for .toJson implementing variables would be good, yes

[zhaoyi0113]

Where should I define LastEvaluatedKey?
If I define it inside gql I will get below error:

input LastEvaluatedKey {
          id: String
          timestamp: Int
}

OperationException (GraphQL Errors:
        Validation error of type NonExecutableDefinition: The LastEvaluatedKey definition is not executable.: Undefined location)

[micimize]

@zhaoyi0113 in graphql, inputs are defined in the schema. So, I would look at your schema and see what the method signature of posts is. The lastEvaluatedKey should have a predefined input type that you can reference in your query.

[zhaoyi0113]

I would say the schema is on the server side. So I don't need to define that in client side.
This is my schema:

type Mutation {
	sendPost(post: PostInput): Post
	savePostPhotos(id: ID!, paths: [String]): ID
}

type PaginationKey {
	id: String!
	timestamp: Long
}

input PaginationKeyInput {
	id: String!
	timestamp: Long
}

type Post {
	userId: String!
	message: String
	id: ID!
	timestamp: Long!
	userInfo: UserInfo
	photoPaths: [String]
	pstatus: Int
}

input PostInput {
	userId: String!
	message: String
}

type PostReqResponse {
	posts: [Post]
	lastEvaluatedKey: PaginationKey
}

type Query {
	presignedURL(id: ID!, count: Int!): [String]
	posts(size: Int, lastEvaluatedKey: PaginationKeyInput): PostReqResponse
	post(id: ID!): Post
}

type UserInfo {
	id: ID
	username: String
	firstName: String
	lastName: String
	name: String
	email: String
	picture: String
}

schema {
	query: Query
	mutation: Mutation
}

[micimize]

@zhaoyi0113 so, instead of LastEvaluatedKey, you want to use the input type PaginationKeyInput. So this should work:

await this.gqClient.query(QueryOptions(documentNode: gql('''
        query posts(\$size: Int, \$lastEvaluatedKey: PaginationKeyInput){
          posts(size: \$size, lastEvaluatedKey: \$lastEvaluatedKey) {
            posts {
              id,
              message,
              photoPaths,
              userInfo {
                username,
                picture
              }
            }
            lastEvaluatedKey {
              id
              timestamp
            }
          }
        }
      '''), variables: {
                'size': this.pageSize,
                'lastEvaluatedKey': this._lastEvaluatedKey.toJson(),
              }));

[zhaoyi0113]

awesome, it fixes the issue. Thanks for checking my bug.