0

我有一个包含 imageId 的 Publication 对象，我想用它来创建模式委托并加载整个对象。

出版物类型定义为：

const PublicationType = new GraphQLObjectType({
name: 'Publication',
description: 'Publication Type',
fields: () => ({
id: {
type: GraphQLID
},
callToAction: {
type: CallToActionType
},
userId: {
type: GraphQLID
},
groupId: {
type: GraphQLID
},
instruction: {
type: InstructionType
},
customizedTitle: {
type: GraphQLString
},
content: {
type: GraphQLString
},
activityType: {
type: ActivityType
},
creationTool: {
type: CreationTool
},
gift: {
type: GiftType
},
imageId: {
type: GraphQLInt
},
thumbnailId: {
type: GraphQLInt
},
createdAt: {
type: GraphQLInt
},
updatedAt: {
type: GraphQLInt
}
})
});

媒体类型定义为：

const MediaType = new GraphQLObjectType({
name: 'Media',
description: 'Media Object',
fields: () => ({
id: {
type: GraphQLInt
},
resource: {
type: GraphQLString
},
metadata: {
type: MetadataType
},
discr: {
type: GraphQLString
}
})
});

其中 MetadataType 是代码中定义的另一种类型。

2 个对象通过这些查询公开：

this._schema = new GraphQLObjectType({
name: 'Query',
description: 'Wall Query',
fields: () => ({
getGroupPublications: {
type: new GraphQLList(PublicationType),
args: {
groupId: {type: new GraphQLNonNull(GraphQLInt)},
from: {type: new GraphQLNonNull(GraphQLInt)},
to: {type: new GraphQLNonNull(GraphQLInt)},
},
resolve: (root, args, context) => PublicationResolver.groupPublications(context)
}
}),
});

和

 this._schema = new GraphQLObjectType({
              name: 'Query',
              description: 'Media Query',
              fields: () => ({
                  getMedia: {
                      type: MediaType,
                      args: {
                          mediaId: {type: new GraphQLNonNull(GraphQLInt)}
                      },
                      resolve: (root, args, context) => MediaResolver.mediaLoader(context).load(args.mediaId)
                  }
              }),
          });

现在我正在尝试将所有定义的模式合并到一个模式中并添加一个委托来加载类型 Media 而不是 ImageID 以便下一个类代表我将公开的主要模式：

import {mergeSchemas} from 'graphql-tools';
// other imports ...

class Services {

    private static _instance: Services;
    private _wall: PublicationService;
    private _media: MediaService;

    private constructor() {
        this._media = new MediaService();
        this._wall = new PublicationService();
    }

    public static Instance() {
        return this._instance || (this._instance = new this())
    }

    public MainSchema = async () => Promise.all([this._publication.schema, this._media.schema])
            .then(args => {
                const publicationSchema = args[0];
                const mediaSchema = args[1];

                const linkSchemaDefs = `
                                extend type Publication {
                                    image: Media
                                    thumbnail: Media
                                }`;

                return mergeSchemas({
                    schemas: [publicationSchema, mediaSchema, linkSchemaDefs],
                    resolvers: 
                        {
                            Publication: {
                                image: {
                                    fragment: `... on Publication { imageId }`,
                                    resolve(parent, args, context, info) {
                                        let mediaId = (parent.imageId === parseInt(parent.imageId, 10)) ? parent.imageId : 0;
                                        return info.mergeInfo.delegateToSchema({
                                            schema: mediaSchema,
                                            operation: 'query',
                                            fieldName: 'getMedia',
                                            args: {
                                                mediaId: mediaId,
                                            },
                                            context,
                                            info
                                        })
                                    }
                                },
                                thumbnail: {
                                    fragment: 'fragment PublicationThumbnailFragment on Publication { thumbnailId }',
                                    resolve(parent, args, context, info) {
                                        let mediaId = (parent.thumbnailId === parseInt(parent.thumbnailId, 10)) ? parent.thumbnailId : 0;
                                        return info.mergeInfo.delegateToSchema({
                                            schema: mediaSchema,
                                            operation: 'query',
                                            fieldName: 'getMedia',
                                            args: {
                                                mediaId: mediaId,
                                            },
                                            context,
                                            info
                                        })
                                    }
                                },
                            },
                        },
                });
            })
            .catch(error => Logger.Instance().error({
                    errorName: 'SchemaStitchingError',
                    logName: 'GraphQL Schema Stitching Error',
                    cause: error,
                    message: [`Services GraphQl Schema stitching rejected`],
                })
            );
}

export {Services}

主模式将使用 graphqlExpress 服务器公开给最终用户但是，我可以在模式定义中看到扩展类型。

发布类型架构描述

但是当我尝试使用定义为的查询查询媒体类型的字段图像时

query {
getGroupPublications(groupId:2, from: 1531180800,to: 1532276998) {
id
imageId
image {
resource
}
createdAt
}
}

查询将直接命中 getGroupPublications 出版物，而不考虑 mergeSchema，我收到此错误：

{ errors:
[ { Cannot query field "image" on type "Publication". Did you mean "imageId"?

GraphQL request (5:3)
4: imageId
5: image {
^
6: resource

at Object.Field (/home/docker/workspace/api-gateway/node_modules/graphql/validation/rules/FieldsOnCorrectType.js:65:31)
at Object.enter (/home/docker/workspace/api-gateway/node_modules/graphql/language/visitor.js:324:29)
at Object.enter (/home/docker/workspace/api-gateway/node_modules/graphql/language/visitor.js:366:25)
at visit (/home/docker/workspace/api-gateway/node_modules/graphql/language/visitor.js:254:26)
at visitUsingRules (/home/docker/workspace/api-gateway/node_modules/graphql/validation/validate.js:74:22)
at validate (/home/docker/workspace/api-gateway/node_modules/graphql/validation/validate.js:59:10)
at graphqlImpl (/home/docker/workspace/api-gateway/node_modules/graphql/graphql.js:106:50)
at /home/docker/workspace/api-gateway/node_modules/graphql/graphql.js:66:223
at new Promise ()
at Object.graphql (/home/docker/workspace/api-gateway/node_modules/graphql/graphql.js:63:10)
message: 'Cannot query field "image" on type "Publication". Did you mean "imageId"?',
locations: [Array],
path: undefined } ] }

但是，如果我在没有字段图像的情况下运行查询，它可以正常工作

query {
getGroupPublications(groupId:1, from: 1531180800,to: 1532276998) {
id
imageId
}
}
4

1 回答 1

0

我面临的问题是由于将完整的 Query 传递给远程模式，MergeSchema Resolver 只有在远程模式返回结果后才会执行。

所以在 getGroupPublications 解析器PublicationResolver.groupPublications(context)中，我替换了通过扩展类型添加的字段。

            let queryString = context.req.body.query;
            queryString = queryString.replace(/image[\s\r\n]*?{[^}]*}/gm, "");
            queryString = queryString.replace(/thumbnail[\s\r\n]*?{[^}]*}/gm, "");
            return graphql(schema, queryString,
                null,
                context,
                context.req.body.variables)
于 2018-07-17T21:48:00.787 回答