小编Fem*_*mke的帖子

我正在按照文档（https://aws-amplify.github.io/docs/js/api#amplify-graphql-client）进行查询，但我一直收到以下错误：

TypeError: Must provide Source. Received: undefined

查询如下：

export const listUsers = `query ListUsers(
  $filter: ModelUserFilterInput
  $limit: Int
  $nextToken: String
) {
  listUsers(filter: $filter, limit: $limit, nextToken: $nextToken) {
    items {
      id
      firstName
      prefix
      lastName
      phone
      cigarettesDay
      enableNotifications
      age
      coach {
        id
        name
      }
      stopDate {
        nextToken
      }
      notifications {
        nextToken
      }
    }
    nextToken
  }
}
`;

使用API.graphqlI 调用查询如下：

  async componentDidMount() {
    try {
      const result = await API.graphql(graphqlOperation(listUsers));
      console.log(result);
    } catch (err) {
      console.log(err);
    } …