使用GraphQL工具模拟GraphQL服务器似乎失败了

Question

我一直关注the documentation about using graphql-tools to mock a GraphQL server，但是这会为自定义类型抛出一个错误，例如：

Expected a value of type "JSON" but received: [object Object]

关于mocking的graphql-tools文档明确声明它们支持自定义类型，甚至提供了使用graphql- type -json项目中的GraphQLJSON自定义类型的示例。

我已经提供了a demo of a solution on github，它使用GraphQL工具成功地模拟了GraphQL服务器，但这依赖于对构建的模式进行简单的修补：

// Here we Monkey-patch the schema, as otherwise it will fall back
// to the default serialize which simply returns null.
schema._typeMap.JSON._scalarConfig.serialize = () => {
    return { result: 'mocking JSON monkey-patched' }
}

schema._typeMap.MyCustomScalar._scalarConfig.serialize = () => {
    return mocks.MyCustomScalar()
}

可能我在我的演示中做错了什么，但如果没有上面的猴子补丁代码，我会得到上面提到的关于自定义类型的错误。

有没有人有比我的演示更好的解决方案，或者关于我可能做错了什么的任何线索，以及我如何更改代码，以便演示在不修补模式的情况下工作？

demo index.js中的相关代码如下：

/*
** As per:
** http://dev.apollodata.com/tools/graphql-tools/mocking.html
** Note that there are references on the web to graphql-tools.mockServer,
** but these seem to be out of date.
*/

const { graphql, GraphQLScalarType } = require('graphql');
const { makeExecutableSchema, addMockFunctionsToSchema } = require('graphql-tools');
const GraphQLJSON = require('graphql-type-json');

const myCustomScalarType = new GraphQLScalarType({
  name: 'MyCustomScalar',
  description: 'Description of my custom scalar type',
  serialize(value) {
    let result;
    // Implement your own behavior here by setting the 'result' variable
    result = value || "I am the results of myCustomScalarType.serialize";
    return result;
  },
  parseValue(value) {
    let result;
    // Implement your own behavior here by setting the 'result' variable
    result = value || "I am the results of myCustomScalarType.parseValue";
    return result;
  },
  parseLiteral(ast) {
    switch (ast.kind) {
      // Implement your own behavior here by returning what suits your needs
      // depending on ast.kind
    }
  }
});

const schemaString = `
    scalar MyCustomScalar
    scalar JSON

    type Foo {
        aField: MyCustomScalar
        bField: JSON
        cField: String
    }

    type Query {
        foo: Foo
    }
`;
const resolverFunctions = {
    Query: {
        foo: {
            aField: () => {
                return 'I am the result of resolverFunctions.Query.foo.aField'
            },
            bField: () => ({ result: 'of resolverFunctions.Query.foo.bField' }),
            cField: () => {
                return 'I am the result of resolverFunctions.Query.foo.cField'
            }
        },
    },
};

const mocks = {
    Foo: () => ({
        // aField: () => mocks.MyCustomScalar(),
        // bField: () => ({ result: 'of mocks.foo.bField' }),
        cField: () => {
            return 'I am the result of mocks.foo.cField'
        }
    }),

    cField: () => {
        return 'mocking cField'
    },

    MyCustomScalar: () => {
        return 'mocking MyCustomScalar'
    },

    JSON: () => {
        return { result: 'mocking JSON'}
    }
}

const query = `
{
  foo {
      aField
      bField
      cField
  }
}
`;

const schema = makeExecutableSchema({
    typeDefs: schemaString,
    resolvers: resolverFunctions
})

addMockFunctionsToSchema({
    schema,
    mocks
});

// Here we Monkey-patch the schema, as otherwise it will fall back
// to the default serialize which simply returns null.
schema._typeMap.JSON._scalarConfig.serialize = () => {
    return { result: 'mocking JSON monkey-patched' }
}

schema._typeMap.MyCustomScalar._scalarConfig.serialize = () => {
    return mocks.MyCustomScalar()
}

graphql(schema, query).then((result) => console.log('Got result', JSON.stringify(result, null, 4)));

Answer 1

我和其他一些人在实时数据源(在我的例子中是MongoDB/Mongoose)也看到了类似的问题。我怀疑这是graphql-tools makeExecutableSchema的内部特性，以及它通过自定义类型摄取基于文本的模式的方式。

这是关于这个问题的另一篇文章：How to use graphql-type-json package with GraphQl

我还没有尝试过在代码中构建模式的建议，所以不能确认它是否有效。

我目前的解决方法是，在向客户端提供JSON字段(以及在客户端进行解析)时，将JSON字段(在连接器中)串行化，反之亦然。有点笨拙，但我并没有真正使用GraphQL来查询和/或选择性地提取JSON对象中的属性。我怀疑这对于大型JSON对象并不是最优的。

Answer 2

如果还有其他人来自谷歌结果，我的解决方案是将JSON解析器作为参数添加到makeExecutableSchema调用中。如下所示：

https://github.com/apollographql/apollo-test-utils/issues/28#issuecomment-377794825

这使得嘲笑对我来说是有效的。