Web框架 --- 解析Web请求 [FromBody] [FromQuery] [FromRoute] [FromHeader]

[FromBody]

• FromBody 属性在使用 application/json 内容类型并在正文中传递 JSON 时使用
• 通常情况下，FromBody 在一个操作中只能用传一个参数。因此，如果在 JSON 正文中传递了多个值，则需要将每个属性添加到一个类中，并将该类用作操作参数的类型.
• 一般只有POST和PUT使用FromBody

// Customer.cs
public class Customer
{public string Forename { get; init; }public string Surname { get; init; }
}

• 这个属性只有在控制器中没有使用 ApiController 属性时才需要使用

[Route("api/from-mvc")]
public class FromMvcController : Controller
{...[HttpPost("from-body")]public IActionResult FromBody([FromBody]string forename){return Ok(new { forename });}
}

• 如果继承了ApiController可以直接写参数，不需要[FromBody]

// FromApiController.cs
[Route("api/from-api")]
public class FromApiController : ApiController
{...[HttpPost("from-body")]public IActionResult FromBody(Customer customer){return Ok(new { customer.Forename, customer.Surname });}
}

[FromQuery]

• [FromQuery] 用于从uri中的query string (? 后面的部分) 取得参数. query string 可以有多个参数，用 & 符号进行分隔

 Uri: /api/from-api/from-query?name="test"&page=4

[Route("api/from-api")]
public class FromApiController : ApiController
{[HttpGet("from-query")]public IActionResult FromQuery([FromQuery] string name, [FromQuery] int page){return Ok(new { name, page });}...
}

• [FromQuery] 可以是optional. 用 [Optional] attribute 或者给参数设置default value

[Route("api/from-api")]
public class FromApiController : ApiController
{[HttpGet("from-query")]public IActionResult FromQuery([Optional][FromQuery] string name){return Ok(new { name, page });}...
}

[Route("api/from-api")]
public class FromApiController : ApiController
{[HttpGet("from-query")]public IActionResult FromQuery([FromQuery] string name = string.Empty, [FromQuery] int page){return Ok(new { name, page });}...
}

[FromRoute] or [FromUri]

• 从uri路径里拿参数, 两种定义方式如下：

• [HttpGet, Route("from-route/{category}")]
• [HttpGet("from-route/{category}")]

Uri: /api/from-api/from-route/blazor

// FromApiController.cs
[Route("api/from-api")]
public class FromApiController : ApiController
{//这里在路径中给对于位置的参数命名{category}[HttpGet("from-route/{category}")]public IActionResult FromRoute([FromRoute] string category){return Ok(new { category });}
}

Uri: /api/from-api/from-route-with-name/blazor

//传入时起一个别名"categoryName"
//[FromRoute(Name = "category")] string categoryName
[HttpGet("from-route-with-name/{category}")]
public IActionResult FromRouteWithName([FromRoute(Name = "category")] string categoryName)
{return Ok(new { categoryName });
}

[FromHeader]

• 从http request中的header中提取信息 （header中有很多kv pair）

GET /data HTTP/1.1
Host: api.example.com
Authorization: Bearer your-access-token
Content-Type: application/json
Accept: application/json
User-Agent: MyApp/1.0

// FromApiController.cs
// Http request header： Authorization: Bearer abcd
[ApiController]
[Route("api/from-api")]
public class FromApiController : Controller
{[HttpGet("from-header")]public IActionResult FromHeader([FromHeader] string authorization){return Ok(new { authorization });}
}