LINQ选择语法将返回所有列而不是选定的列

Question

我试图从表中选择并返回某些列，查询将忽略该选择并返回除相关表中相关字段以外的所有列。 如何仅返回选定的列？

这是我API Controller，

[Produces("application/json")] 
    [Route("api/Common")] 
public class CommonController : Controller 
{ 
    private readonly ArtCoreDbContext _context; 

    public CommonController(ArtCoreDbContext context) 
    { 
     _context = context; 
    } 

    [HttpGet] 
    public IEnumerable<IdState> GetState() 
    { 
     return _context.IdState; 
    } 

    [HttpGet("{id}")] 
    public async Task<IActionResult> GetState([FromRoute] int id) 
    { 
     var L2EQuery = await (from i in _context.IdState 
             select new { Id = i.StaeId, i.text }).ToListAsync(); 

     return Ok(L2EQuery); 
    } 
} 

更新

这是模型，

public class IdState 
     { 
      [DatabaseGenerated(DatabaseGeneratedOption.Identity), Key] 
      public int StaeId { set; get; } 
      public int CouyId { set; get; } 
      [Display(Name = "State"), Required] 
      public string text { set; get; } 
      public ICollection<PatReg> State { get; set; } 
      public ICollection<IdCity> TblIdCity { get; set; } 

     } 

和输出，

[{ 
    "staeId": 1, 
    "couyId": 2, 
    "text": "California", 
    "state": null, 
    "tblIdCity": null 
}, { 
    "staeId": 2, 
    "couyId": 2, 
    "text": "WA", 
    "state": null, 
    "tblIdCity": null 
}, { 
    "staeId": 3, 
    "couyId": 1, 
    "text": "Ajloun", 
    "state": null, 
    "tblIdCity": null 
}, { 
    "staeId": 4, 
    "couyId": 1, 
    "text": "Amman", 
    "state": null, 
    "tblIdCity": null 
}] 

ajax呼叫

使用LINQPad 5我得到的只有选中的列，

Answer 1

我认为，你可以调用方法public IEnumerable<IdState> GetState()并返回给你整个表。

也许，你需要调用Task<IActionResult> GetState([FromRoute] int id)

问题是在这里： url: "/api/Common",你叫错了方法，添加参数：

url: "/api/Common/123",

或可能：

$(function() { 
     $.ajax({ 
      type: "Get", 
      url: "/api/Common", 
      data: {id: 123}, 
      contentType: "application/json; charset=utf-8", 
      dataType: "json", 
      success: function (response) { 
       console.log(response); 
      }, 
      failure: function (response) { 
       alert(response.responseText); 
      }, 
      error: function (response) { 
       alert(response.responseText); 
      } 
     }); 
    }); 

Answer 2

可以吗请试试

public class CommonController : Controller 
    { 

     private readonly ArtCoreDbContext _context; 

     public CommonController(ArtCoreDbContext context) 
     { 
      _context = context; 
     } 

     [HttpGet] 
     public IEnumerable<IdState> GetState() 
     { 

      return _context.IdState; 
     } 
     [HttpGet("{id}")] 
     public async Task<IActionResult> GetState([FromRoute] int id) 
     { 
      var L2EQuery = await (from i in _context.IdState 
            where i.test.equals("abc") 
             select new { Id = i.StaeId, text= i.text }).ToListAsync(); 

      return Ok(L2EQuery); 
     } 
    } 

Answer 3

您的C＃代码没有问题，但JavaScript。

您没有在控制器中指定操作，因此它默认为无参数HttpGet启用操作，该操作不会投影任何字段。所以问题在于你的AJAX调用。更正像这样：

$.ajax({ 
    type: "Get", 
    // Pay attention on the next line ! 
    url: "/api/Common/123", 
    contentType: "application/json; charset=utf-8", 
    dataType: "json", 
    success: function (response) { 
     console.log(response); 
    }, 
    failure: function (response) { 
     alert(response.responseText); 
    }, 
    error: function (response) { 
     alert(response.responseText); 
    } 
}); 

“123”只是一个例子，但是我所看到的，目前也没有关系，因为你不过滤你的LINQ什么。但是，您必须在URL中指定它，以便可以将其解析为正确的方法。