从AWS获得响应|应用同步

Question

几天前，我已经成功集成了AWS-Client-App示例，然后从零开始。让我给您我的项目说明：-

Xcode version : Version 9.4 (9F1027a)
Language : Swift 4.0
Database : DynamoDB
And Using AppSync for syncing database

我有一个模式

type Mutation {
    #------ User ------#
    CreateUser(
        FirstName: String,
        Username: String,
        Password: String,
        CreatedOn: Int
    ): User
    UpdateUser(UserId: ID!, FirstName: String!, Username: String!): User
    DeleteUser(UserId: ID!): User
}

type Query {
    ####------ User ------#
    GetUser(UserId: ID!): User
    CheckUsername(Username: String): [User]
    CheckPhoneNumber(Phone: String): [User]
    #------ Login ------#
    CheckUserLogin(Username: String, Password: String): [User]
}

type User {
    UserId: ID!
    FirstName: String
    Username: String
    #Password: String
    Bio: String
    Phone: String
    Email: String
    Address: String
    WebsiteUrl: String
    ProfilePicture: String
    CreatedOn: Int
    Updated: Int
    Status: Boolean
    LastLoggedIn: Int
    IpAddress: String
}

schema {
    query: Query
    mutation: Mutation
}

.graphql文件中的简单查询

query CheckUsername($Username:String){
  CheckUsername(Username:$Username)
  {
      Username
  }
}

并生成了一个名为check Queries.swift的文件

import AWSAppSync

public final class CheckUsernameQuery: GraphQLQuery {
  public static let operationString =
    "query CheckUsername($Username: String) {\n  CheckUsername(Username: $Username) {\n    __typename\n    Username\n  }\n}"

  public var Username: String?

  public init(Username: String? = nil) {
    self.Username = Username
  }

  public var variables: GraphQLMap? {
    return ["Username": Username]
  }

  public struct Data: GraphQLSelectionSet {
    public static let possibleTypes = ["Query"]

    public static let selections: [GraphQLSelection] = [
      GraphQLField("CheckUsername", arguments: ["Username": GraphQLVariable("Username")], type: .list(.object(CheckUsername.selections))),
    ]

    public var snapshot: Snapshot

    public init(snapshot: Snapshot) {
      self.snapshot = snapshot
    }

    public init(checkUsername: [CheckUsername?]? = nil) {
      self.init(snapshot: ["__typename": "Query", "CheckUsername": checkUsername.flatMap { $0.map { $0.flatMap { $0.snapshot } } }])
    }

    public var checkUsername: [CheckUsername?]? {
      get {
        return (snapshot["CheckUsername"] as? [Snapshot?]).flatMap { $0.map { $0.flatMap { CheckUsername(snapshot: $0) } } }
      }
      set {
        snapshot.updateValue(newValue.flatMap { $0.map { $0.flatMap { $0.snapshot } } }, forKey: "CheckUsername")
      }
    }

    public struct CheckUsername: GraphQLSelectionSet {
      public static let possibleTypes = ["User"]

      public static let selections: [GraphQLSelection] = [
        GraphQLField("__typename", type: .nonNull(.scalar(String.self))),
        GraphQLField("Username", type: .scalar(String.self)),
      ]

      public var snapshot: Snapshot

      public init(snapshot: Snapshot) {
        self.snapshot = snapshot
      }

      public init(username: String? = nil) {
        self.init(snapshot: ["__typename": "User", "Username": username])
      }

      public var __typename: String {
        get {
          return snapshot["__typename"]! as! String
        }
        set {
          snapshot.updateValue(newValue, forKey: "__typename")
        }
      }

      public var username: String? {
        get {
          return snapshot["Username"] as? String
        }
        set {
          snapshot.updateValue(newValue, forKey: "Username")
        }
      }
    }
  }
}

然后我调用了这段代码来运行查询

let query = CheckUsernameQuery(Username:"testuser1")
AppSyncManager.Client().fetch(query: query, cachePolicy: .fetchIgnoringCacheData) {
    (result, error) in
    if error != nil {
        print(error?.localizedDescription ?? "")
        return
    }
    let username = result?.data?.checkUsername![0]?.username
}

我得到以下答复

▿ Optional<GraphQLResult<Data>>
  ▿ some : GraphQLResult<Data>
    - data : nil
    - errors : nil
    - source : AWSAppSync.GraphQLResult<AppName.CheckUsernameQuery.Data>.Source.server
    - dependentKeys : nil

当我在Appsync Api面板中对其进行测试但该查询无法在该应用程序中运行时，该查询效果很好。没有错误，没有数据，什么都没有？如果任何人有一个主意让我知道，我可能会做错什么，这对我有很大的帮助。谢谢。