网络错误：无法读取未定义的属性“登录”

Question

提交凭据时，我有一个登录页面，请启动此方法：

const login = gql`mutation login ($username: String!, $password: String!) {
    login (
        username: $username,
        password: $password
        client_id: 2
        client_secret: "XXXXXXXXXXXXXXXXXXXXXXXXXXXX"
    ) {
        auth_token {
            access_token
        }
        user {
            email
        }
    }
}`;
...
login(username: string, password: string) 
{
      return this.apollo.mutate({
            mutation: login,
            variables: {
                username: username,
                password: password
            }
      });
}

在我需要使用以下方法来获取我的API上的所有用户后：

const users = gql`query users ($first: Int!, $page: Int, $orderBy: [OrderByClause!]) {
    users (
        first: $first,
        page: $page,
        orderBy: $orderBy
    ) {
        data {
            id
            name
            email
        }
    }
}`;
...
public getAll(first: number, page: number, orderBy: any[] = []): Observable<any> 
{
        return this.apollo.query({
            query: users,
            variables: {
                first: first,
                page: page,
                orderBy: orderBy
            }
        });
}

一切正常，但是当我重新加载页面时，出现此错误：Network error: Cannot read property 'login' of undefined，因为我认为这是缓存或链接的问题。在这种情况下您收到此错误了吗？

我的graphql.module.ts：

import { NgModule } from '@angular/core';
import { ApolloModule, APOLLO_OPTIONS } from 'apollo-angular';
import { HttpLinkModule, HttpLink } from 'apollo-angular-link-http';
import { InMemoryCache } from 'apollo-cache-inmemory';

const uri = 'https://my-application-api.dev/graphql';
export function createApollo(httpLink: HttpLink) {
    return {
        link: httpLink.create({uri}),
        cache: new InMemoryCache()
    };
}

@NgModule({
    exports: [ApolloModule, HttpLinkModule],
    providers: [
        {
            provide: APOLLO_OPTIONS,
            useFactory: createApollo,
            deps: [HttpLink],
        },
    ],
})
export class GraphQLModule {}

感谢您的帮助。