Execution Return value type checking about graphql HOT 5 CLOSED

Hi @pyros2097

Thanks for bringing this up 👍🏻

Could help to share the expected error message if you would have run it against graphql-js?

Thanks! Cheers!

from graphql.

Here are the 2 examples,

package main

import (
    "encoding/json"
    "github.com/chris-ramon/graphql-go"
    "github.com/chris-ramon/graphql-go/types"
)

var UserType = types.NewGraphQLObjectType(types.GraphQLObjectTypeConfig{
    Name:        "User",
    Description: "A user",
    Fields: types.GraphQLFieldConfigMap{
        "id": &types.GraphQLFieldConfig{
            Type: types.NewGraphQLNonNull(types.GraphQLInt),
        },
        "name": &types.GraphQLFieldConfig{
            Type: types.GraphQLInt,
        },
    },
})

func main() {
    Schema, err := types.NewGraphQLSchema(types.GraphQLSchemaConfig{
        Query: types.NewGraphQLObjectType(types.GraphQLObjectTypeConfig{
            Name: "AA",
            Fields: types.GraphQLFieldConfigMap{
                "user": &types.GraphQLFieldConfig{
                    Type: UserType,
                    Resolve: func(p types.GQLFRParams) interface{} {
                        return map[string]interface{}{"id": "hello", "name": "hello"}
                    },
                },
            },
        }),
    })
    if err != nil {
        panic(err.Error())
    }
    resultChannel := make(chan *types.GraphQLResult)
    params := gql.GraphqlParams{
        Schema:        Schema,
        RootObject:    nil,
        RequestString: "query Test { user { id name } }",
    }
    go gql.Graphql(params, resultChannel)
    result, err := json.Marshal(<-resultChannel)
    if err != nil {
        panic(err.Error())
    }
    println(string(result))
}

import {
  GraphQLSchema,
  GraphQLObjectType,
  GraphQLString,
  GraphQLNonNull,
  GraphQLList,
  GraphQLBoolean,
  GraphQLInt,
  GraphQLFloat,
  GraphQLEnumType,
  GraphQLScalarType,
  GraphQLInputObjectType,
  GraphQLUnionType,
  graphql
} from 'graphql'

import {
  Kind
} from 'graphql/language'

import {
  GraphQLError
} from 'graphql/error'

var UserType = new GraphQLObjectType({
  name: 'User',
  description: 'A typical user',
  fields: {
    id: {
      type: new GraphQLNonNull(GraphQLString),
      description: 'The id of the user'
    },
    name: {
      type: new GraphQLNonNull(GraphQLInt),
      description: 'The full name of the user'
    },
  }
})

var Schema = new GraphQLSchema({
  query: new GraphQLObjectType({
    name: 'Query',
    fields: {
      user: {
        type: UserType,
        resolve(user, args, root) {
          return {
            id: "test",
            name: "test"
          }
        }
      },
    }
  }),
})

graphql(Schema, 'query Test { user { id name } }')
.then((result) => {
  console.log(result)
})

// Cannot return null for non-nullable field User.id.
// User Error: expected iterable, but did not find one.

It seems it even the graphql-js doesn't do any typechecking. We are actually porting the graphql-js backend which we wrote earlier to go and I seemed to recall this error when I was developing in js. So I'll dig into it more and see when and where this ocurred

from graphql.

Hi @pyros2097

Thanks for providing the examples 👍🏻
Just for completeness sake, I've ran the examples you provided and ran both in graphql-js and graphql-go for confirm the output. They are expected to give the same output.

First example:

In this example, id field is defined as GraphQLInt but returns a String value, so it returns a null value.
(Related gist: https://gist.github.com/sogko/a47c71711ed486dad15a)

Both graphql-js and graphql-go returned the same output.

{ data: { user: { id: null } } }

Second example

Both graphql-js and graphql-go returned the same output.

{ data: { user: { id: 'test', name: null } } }

Third example

Both graphql-js and graphql-go returned the same error in the output:

{ data: { user: null },
  errors:
   [ { [Error: Cannot return null for non-nullable field User.name.]
       message: 'Cannot return null for non-nullable field User.name.' } ] }

Note: Neither should return User Error: expected iterable, but did not find one. since none of the fields are defined with GraphQLList.

It seems it even the graphql-js doesn't do any typechecking.

Actually all the above are the expected behaviour.

• As per spec: Types are nullable by default.
• Resolving field with an error (for e.g. returning the wrong value type) will set the field to null. (See the tests in executor/nonnull_test.go, though there isn't a specific test for that but it is implied. We could add that to the test suite)
• For example 1 and 2, since both fields are nullable, returning the wrong type will set them to null and no errors are returned.
• For example 3, the name field is defined as non-nullable Int but the resolve function returns a string.
  • This sets the field to null, which violates the defined schema, hence the Cannot return null for non-nullable field User.name. error message.

If you want to enforce strict type-checking for return type, I suggest taking advantage of Go for that.

Taking your example:

package main
import (
    "encoding/json"
    "github.com/chris-ramon/graphql-go"
    "github.com/chris-ramon/graphql-go/types"
)

// Define a Go struct
// Note the `json` tags maps to the GraphQL field names,
// for e.g User.ID => `json:"id"`
type User struct {
    ID int  `json:"id"`
    Name string `json:"name"`
}
var UserType = types.NewGraphQLObjectType(types.GraphQLObjectTypeConfig{
    Name:        "User",
    Description: "A typical user",
    Fields: types.GraphQLFieldConfigMap{
        "id": &types.GraphQLFieldConfig{
            Type: types.NewGraphQLNonNull(types.GraphQLInt),
        },
        "name": &types.GraphQLFieldConfig{
            Type: types.NewGraphQLNonNull(types.GraphQLString),
        },
    },
})
func main() {
    Schema, err := types.NewGraphQLSchema(types.GraphQLSchemaConfig{
        Query: types.NewGraphQLObjectType(types.GraphQLObjectTypeConfig{
            Name: "Query",
            Fields: types.GraphQLFieldConfigMap{
                "user": &types.GraphQLFieldConfig{
                    Type: UserType,
                    Resolve: func(p types.GQLFRParams) interface{} {
                        // return `User` struct instead of `map[string]interface{}` for compile-time type-checking
                        return &User{
                            ID: 1, // there's no room for anyone to mistakenly return a string for ID field
                            Name: "Hello",
                        }
                    },
                },
            },
        }),
    })
    ...
}
// output:
{"data":{"user":{"id":1,"name":"Hello"}}}

Notes

• for user field, we return the User struct we defined, instead of using map[string]interface{}
• Each field type in the User struct maps to the type defined in the GraphQL schema.
  • For example User.ID int => UserType.Fields.id.Type = GraphQLInt
• Take note that we use json tags in the User struct to map each field to the corresponding GraphQL field.

Let me know what you think!

from graphql.

Hi @sogko,

Thanks for your input. Its seems you did a lot of research into this. Yeah you are exactly right this is how it works according to the spec. But Still need to test out various features like custom scalars and check if they also validate with graphql-js.
There are still some parts in graphql-go that doesn't seem to work like graphql-js. I will open other issues for that and will thoroughly test it against graphql-js because we will be using it in out production app.

from graphql.

@pyros2097 Do share with us if you find disparity in behaviour between graphql-go and graphql-js 👍🏻

Closing this issue.
Feel free to re-open if you feel that your concern has not been addressed.

from graphql.