Neo4j/GraphQL 增强模式

Posted 2023-03-08

【中文标题】Neo4j/GraphQL 增强模式

【英文标题】：Neo4j/GraphQL augmented Schema

【发布时间】：2019-01-01 07:37:19

【问题描述】：

我正在尝试了解 Neo4j 的 GraphQL 集成。我正在使用可以在此处找到的 GrandStack 启动器。 Grand Stack Starter。启动器没有使用您在其他 GrapQL 应用程序中看到的大量样板，因为据我了解，Neo4j 集成应该绕过双重声明 Schema 和 Resolvers 的需要。它改用 Apollo Server 和“augmentedSchema”。使用起始代码，我尝试向模式添加一些突变，在本例中为 deleteUser 突变。我一直收到一个错误，说 Mutation id 定义了不止一次，当我知道我只是把它放在一个地方的代码中。这是我的 schema.js：

    import  neo4jgraphql  from "neo4j-graphql-js";

export const typeDefs = `
type User 
  id: ID!
  name: String
  friends(first: Int = 10, offset: Int = 0): [User] @relation(name: "FRIENDS", direction: "BOTH")
  reviews(first: Int = 10, offset: Int = 0): [Review] @relation(name: "WROTE", direction: "OUT")
  avgStars: Float @cypher(statement: "MATCH (this)-[:WROTE]->(r:Review) RETURN toFloat(avg(r.stars))")
  numReviews: Int @cypher(statement: "MATCH (this)-[:WROTE]->(r:Review) RETURN COUNT(r)")


type Business 
  id: ID!
  name: String
  address: String
  city: String
  state: String
  reviews(first: Int = 10, offset: Int = 0): [Review] @relation(name: "REVIEWS", direction: "IN")
  categories(first: Int = 10, offset: Int =0): [Category] @relation(name: "IN_CATEGORY", direction: "OUT")


type Review 
  id: ID!
  stars: Int
  text: String
  business: Business @relation(name: "REVIEWS", direction: "OUT")
  user: User @relation(name: "WROTE", direction: "IN")


type Category 
  name: ID!
  businesses(first: Int = 10, offset: Int = 0): [Business] @relation(name: "IN_CATEGORY", direction: "IN")


type Query 
    users(id: ID, name: String, first: Int = 10, offset: Int = 0): [User]
    businesses(id: ID, name: String, first: Int = 10, offset: Int = 0): [Business]
    reviews(id: ID, stars: Int, first: Int = 10, offset: Int = 0): [Review]
    category(name: ID!): Category
    usersBySubstring(substring: String, first: Int = 10, offset: Int = 0): [User] @cypher(statement: "MATCH (u:User) WHERE u.name CONTAINS $substring RETURN u")


type Mutation 

    deleteUser(id: ID!): User


`;

export const resolvers = 
    Query: 
        users: neo4jgraphql,
        businesses: neo4jgraphql,
        reviews: neo4jgraphql,
        category: neo4jgraphql,
        usersBySubstring: neo4jgraphql
    ,

    Mutation: 
        deleteUser: neo4jgraphql
    
;

这是我的索引：

import  typeDefs, resolvers  from "./graphql-schema";
import  ApolloServer, gql, makeExecutableSchema  from "apollo-server";
import  v1 as neo4j  from "neo4j-driver";
import  augmentSchema  from "neo4j-graphql-js";
import dotenv from "dotenv";

dotenv.config();

const schema = makeExecutableSchema(
  typeDefs,
  resolvers
);

// augmentSchema will add autogenerated mutations based on types in schema
const augmentedSchema = augmentSchema(schema);

const driver = neo4j.driver(
    process.env.NEO4J_URI || "bolt://localhost:7687",
    neo4j.auth.basic(
    process.env.NEO4J_USER || "neo4j",
    process.env.NEO4J_PASSWORD || "neo4j"
    )
);

if (driver)
    console.log("Database Connected")
 else
    console.log("Database Connection Error")


const server = new ApolloServer(
  // using augmentedSchema (executable GraphQLSchemaObject) instead of typeDefs and resolvers
  //typeDefs,
  //resolvers,
  context:  driver ,
  // remove schema and uncomment typeDefs and resolvers above to use original (unaugmented) schema
  schema: augmentedSchema
);

server.listen(process.env.GRAPHQL_LISTEN_PORT, '0.0.0.0').then(( url ) => 
  console.log(`GraphQL API ready at $url`);
);

错误信息：

启动器中没有其他代码被更改。我无法在文档中找到有关 augmentedSchema 的太多信息。如果有人能指出我正确的方向，我将不胜感激。

【参考方案1】：

问题是由augmentedSchema 引起的，它会自动为每种类型创建默认突变，即在这种情况下，它已经创建了删除用户、更新用户和添加用户。您可以在运行 GraphiQL 服务器时看到这一点。所以我双重声明删除用户突变。