ASP.NET Core MVC调用Yelp GraphQL API遇错及解决方案

问题描述 #

我正尝试在ASP.NET Core MVC应用中使用GraphQLHttpClient调用Yelp GraphQL API的商家端点，已在客户端实例中配置好API地址和Bearer Token。参照指定的查询结构，仅想获取数据中的Id和Name字段，但调用SendQueryAsync(query)时收到GraphQL错误，不确定是请求参数还是查询语句有误，找不到相关C#调用示例，寻求帮助。

问题已解决 #

问题涉及多个方面，修复点如下：

• 为Yelp GraphQL查询补充了带变量的必填字段
• 使用JsonPropertyName特性处理字段大小写匹配问题
• 修复并补充了对应响应结构的实体类
• 通过依赖注入将SearchConsumer类注入到控制器中

以下是完整实现代码：

实体类与消费者定义 #

public class Business
{
    [JsonPropertyName("id")]
    public string Id { get; set; }
    [JsonPropertyName("name")]
    public string Name { get; set; }
}

public class Search
{
    [JsonPropertyName("business")]
    public List<Business> business { get; set; }
}

public class SearchResponseType
{
    [JsonPropertyName("search")]
    public Search Search { get; set; }
}

public interface ISearchConsumer
{
    Task<List<Business>> GetAllBusinesses();
}

public class SearchConsumer : ISearchConsumer
{
    private readonly ApplicationDbContext _dbContext;

    public SearchConsumer(ApplicationDbContext dbContext)
    {
        _dbContext = dbContext;
    }

    public async Task<List<Business>> GetAllBusinesses()
    {
        var authorization = _dbContext.Authorizations.FirstOrDefault().Token;
        var _client = new GraphQLHttpClient("https://api.yelp.com/v3/graphql", new NewtonsoftJsonSerializer());
        _client.HttpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", authorization);
        var query = new GraphQLRequest
        {
            Query = @"
            query($termId: String $locationId: String){
                search(term:$termId location:$locationId) {
                    business {
                        id
                        name
                    }
                }
            }",
            Variables = new
            {
                termId = "burrito",
                locationId = "san francisco"
            }
        };
        var response = await _client.SendQueryAsync<SearchResponseType>(query);
        var businesses = response.Data.Search.business;
        return businesses;
    }
}

控制器代码 #

public class YelpGraphQLController : Controller
{
    private readonly ISearchConsumer _consumer;

    public YelpGraphQLController(ISearchConsumer consumer)
    {
        _consumer = consumer;
    }

    public IActionResult Index()
    {
        return View();
    }

    [HttpGet]
    public async Task<IActionResult> Get()
    {
        var businesses = await _consumer.GetAllBusinesses();
        return Ok(businesses);
    }
}

依赖注入配置 #

ConfigureServices(builder.Services);

void ConfigureServices(IServiceCollection services)
{
    services.AddTransient<ISearchConsumer, SearchConsumer>();
}

Yelp GraphQL返回数据示例 #

{
  "data": {
    "search": {
      "business": [
        {
          "id": "wGl_DyNxSv8KUtYgiuLhmA",
          "name": "Bi-Rite Creamery"
        },
        {
          "id": "lJAGnYzku5zSaLnQ_T6_GQ",
          "name": "Brenda's French Soul Food"
        }
      ]
    }
  }
}

内容的提问来源于stack exchange，提问作者bliu