使用 thunk 的 GraphQL 循环引用 - 错误：字段类型必须是输出类型，但得到：未定义

Question

我必须解决 GraphQL 的循环定义，但由于某种原因我无法解决。我检查了几篇关于 thunk 和延迟加载的帖子，这是我当前的代码：

历史/types.js

const fields = {
    id: {
        type: new GraphQLNonNull(GraphQLID),
        resolve: (obj) => dbIdToNodeId(obj._id, "History")
    },
    timestamp: {
        type: GraphQLLong
    },
    objectId: {
        type: GraphQLString
    },
    user: {
        type: require('../User/connections').default,
        args: connectionArgs,
        resolve: (source, args) => {
            return UserModel.findOne({ id: source.id }).exec();
        }
    },
    action: {
        type: new GraphQLNonNull(GraphQLString)
    }
};

export const HistoryType = new GraphQLObjectType({
    name: 'History',
    description: 'History',
    interfaces: () => [NodeInterface],
    isTypeOf: (value) => value instanceof HistoryModel,
    fields: () => (fields)
});

历史/connections.js：

import { HistoryType } from './types';
const { connectionType: HistoryConnectionType } = connectionDefinitions( { nodeType: HistoryType });

export default HistoryConnectionType;

用户/types.js

const fields = {
    id: {
        type: new GraphQLNonNull(GraphQLID),
        resolve: (obj) => dbIdToNodeId(obj._id, "User")
    },
    email: {
        type: GraphQLString
    },
    history: {
        type: require('../History/connections').default,
        args: connectionArgs,
        resolve: (source, args, context) => {
            return HistoryModel.find({ deleted: false, objectId: source.id}).sort('timestamp').exec();
        }
    }
};

export const UserType = new GraphQLObjectType({
    name: 'User',
    description: 'User',
    interfaces: () => [NodeInterface],
    isTypeOf: (value) => value instanceof UserModel,
    fields: () => (fields)
});

用户/connections.js

import { UserType } from './types';

const { connectionType: UserConnectionType } = connectionDefinitions( { nodeType: UserType });

export default UserConnectionType;

公司/types.js

const fields = {
    id: {
        type: new GraphQLNonNull(GraphQLID),
        resolve: (obj) => dbIdToNodeId(obj._id, "Company")
    },
    name: {
        type: GraphQLString
    },
    users: {
        type: require('../User/connections').default,
        args: connectionArgs,
        resolve: (source, args) => {
            const { id } = source;
            return UserModel.find({ companyId: id }).then((rows) => connectionFromArray(rows,args));
        }
    },
    history: {
        type: require('../History/connections').default,
        args: connectionArgs,
        resolve(source, args, context) {
            return loaders.getHistory(source.id);
        }
    }
};

export const CompanyType = new GraphQLObjectType({
    name: 'Company',
    description: 'Company',
    interfaces: () => [NodeInterface],
    isTypeOf: (value) => value instanceof CompanyModel,
    fields: () => (fields)
});

公司/connections.js

import { CompanyType } from './types';

const { connectionType: CompanyConnectionType } = connectionDefinitions( { nodeType: CompanyType });

export default CompanyConnectionType;

我不能让它工作。运行时，我得到以下输出：

 History.user field type must be Output Type but got: undefined

Answer 1

我猜你现在已经解决了，但是对于任何路过的人：
在history/types.js中，fields对象必须内联在HistoryType的fields函数中，所以它是在运行时创建的。

const HistoryType = new GraphQLObjectType({
  ...
  fields: () => ({ ... }), // not a var, object is inlined
  ...
});