.Net Core WebAPI 绑定源参数推理、接收http参数写法（SuppressInferBindingSourcesForParameters ）

背景：.Net Core WebAPI 控制器中接收参数一般情况下分为简单类型（int、string、double....）、实体类dto、数据集合类型。

 事实上，http请求可以把请求参数放到query、header、form、body中，而.net core WebAPI中默认启用了推理规则，可以自动推理参数在哪里并传入控制器参数中

只是开启默认推理规则时，对于简单类型参数的接收，不能推理出去哪里接收，需要显示指定为[FromForm]或者[FromBody]

以下是默认规则下的接收参数方式：

    /// 

    /// 默认启用参数推理规则时
    /// 
    [Route("api/[controller]/[action]")]
    [ApiController]
    public class TestController : ControllerBase
    {

        [HttpPost]
        public ActionResult AddFormPara1([FromForm]string id)
        {
            //application/x-www-form-urlencoded
            //对于简单类型（string、int），推理不出来，所以需要显示指定参数来源FromForm
            var context = HttpContext.Request;
            return Ok(new { id = id });
        }

        [HttpPost]
        public ActionResult AddFormPara([FromForm] string id, [FromForm] string name)
        {
            //application/x-www-form-urlencoded
            //对于简单类型（string、int），推理不出来，所以需要显示指定参数来源FromForm
            var context = HttpContext.Request;
            return Ok(new { id = id, name = name });
        }

        [HttpPost]
        public IActionResult AddJsonPara1([FromBody] string id)
        {
            //json格式请求过来时Request中的data直接就是id的值，例：data:"111"
            var context = HttpContext.Request;
            return Ok(new { id = id });
        }


        [HttpPost]
        public ActionResult AddJsonPara(dto dto)
        {
            //application/json {"id":"111","name":"winston"}
            var context = HttpContext.Request;
            return Ok(new { id = dto.id, name = dto.name });
        }

        [HttpPost]
        public ActionResult AddJsonParaList(List dto)
        {
            application/json [{"id":"111","name":"winston"}]
            var context = HttpContext.Request;
            return Ok(dto);
        }
    
        //[HttpPost]
        //public ActionResult AddJsonPara1([FromBody] string id, [FromBody] string name)
        //{
        //    //这种写法是不行的，FromBody只能指定一个参数
        //    var context = HttpContext.Request;
        //    return Ok(new { id = id, name = name });
        //}
    }


    public class dto
    {
        public string id { get; set; }

        public string name { get; set; }

    }

如果不想开启默认推理规则，即可以通过配置SuppressInferBindingSourcesForParameters来禁用

   services.AddControllers(options =>
            {
                
            }).ConfigureApiBehaviorOptions(options =>
            {
                //options.SuppressConsumesConstraintForFormFileParameters = true;//禁用当[FromForm]属性批注时，推理multipart/form-data请求内容类型
                options.SuppressInferBindingSourcesForParameters = true;//禁用api的推理规则，这样就支持post方式直接括号接受参数和model参数方式
            });

禁用推理规则后，WebApi默认从form中取参,此时接参方式：

    /// 

    /// 禁用参数推理规则时
    /// 
    [ApiController]
    [Route("api/[controller]/[action]")]
    public class Test1Controller : ControllerBase
    {

        [HttpPost]
        public IActionResult AddFormPara1(string id)
        {
            //application/x-www-form-urlencoded
            //禁用推理规则后，application/x-www-form-urlencoded对于简单类型就不需要显示指定参数来源FromForm
            //但对于application/json的还是接不到
            var context = HttpContext.Request;
            return Ok(new { id = id });
        }

        [HttpPost]
        public IActionResult AddFormPara(string id,string name)
        {
            //application/x-www-form-urlencoded
            //禁用推理规则后，application/x-www-form-urlencoded对于简单类型就不需要显示指定参数来源FromForm
            //但对于application/json的还是接不到
            var context = HttpContext.Request;
            return Ok(new { id = id, name = name });
        }

        [HttpPost]
        public IActionResult AddJsonPara(dto1 dto)
        {
            //application/x-www-form-urlencoded
            //禁用推理规则后，依然可以用实体类来接收json格式数据，但前提是application/x-www-form-urlencoded
            var context = HttpContext.Request;
            return Ok(new { id = dto.id, name = dto.name });
        }

        [HttpPost]
        public IActionResult AddListJsonPara([FromBody]List dto)
        {
            //禁用推理规则后，对于json格式数据集合参数，需指定FromBody
            var context = HttpContext.Request;
            return Ok(dto);
        }
    }

    public class dto1
    {
        public string id { get; set; }

        public string name { get; set; }

    }

总结：对于.Net Core WebAPI的默认推理规则，最好还是要开启，只是针对简单类型，需要显示指定FromBody或者FromForm，但是对于json格式参数和数据集合参数接收良好。