Http请求

1. HttpHead：1、与GET类似，但没要响应主体；2、检测缓存；3、探测资源是否存在。
   用法：在[HttpGet]方法的attribute下加一个[HttpHead]即可，visual studio会自动识别并把httpGet请求转化为HttpHead请求，即没有响应主体的Get。

2. [HttpPut]更新对象。
   参考AutoMapper

[HttpPut("{touristRouteId}", Name = "UpdateTouristRouteAsync")]
        public async Task<IActionResult> UpdateTouristRoute([FromRoute] Guid touristRouteId, [FromBody] TouristRouteForUpdateDto touristRouteForUpdateDto)
        {
            if (!await _touristRouteRepository.TouristRouteExistAsync(touristRouteId))
            {
                return NotFound("旅游路线找不到");
            }
            var touristRouteFromRepo = await _touristRouteRepository.TouristRouteGetRouteAsync(touristRouteId);
            //1、映射Dto；2、更新Dto；3、映射model
            _mapper.Map(touristRouteForUpdateDto, touristRouteFromRepo);//这一句完成了三步，不是很懂，待补充https://github.com/AutoMapper/AutoMapper/blob/bdc0120497d192a2741183415543f6119f50a982/src/AutoMapper/Mapper.cs

            await _touristRouteRepository.SaveAsync();
            return NoContent();
        }

3. [HttpPatch]
   依赖库：Microsoft.AspNetCore.JsonPatch、Microsoft.AspNetCore.Mvc.NewtonsoftJson
   Patch发送的body数据格式：

{
	{
	"op":"replace",//op操作只允许：add——添加字段，remove——删除字段，replace——替换字段数据，move——转移字段，copy——复制字段，test——测试
	"path":"/titel",//必须有path
	"value":"ABCD"
	},
	{
	"op":"replace",
	"path":"/desciption",
	"value":"ABCD"
	}
}

在使用Json前需要先在startup里注入Json服务
services.AddControllers().AddNewtonsoftJson(setupAction => {setupAction.SerializerSettings.ContractResolver = new CamelCasePropertyNamesContractResolver();}).AddXmlDataContractSerializerFormatters()
然后再调用

        [HttpPatch("{touristRouteId}", Name = "PartiallyUpdateTouristRouteAsync")]
        public async Task<IActionResult> PartiallyUpdateTouristRoute([FromRoute] Guid touristRouteId, [FromBody] JsonPatchDocument<TouristRouteForUpdateDto> patchDocument)
        {
            if (!await _touristRouteRepository.TouristRouteExistAsync(touristRouteId))
            {
                return NotFound("旅游路线找不到");
            }
            var touristRouteFromRepo = await _touristRouteRepository.TouristRouteGetRouteAsync(touristRouteId);
            var touristRouteToPatch = _mapper.Map<TouristRouteForUpdateDto>(touristRouteFromRepo);
            patchDocument.ApplyTo(touristRouteToPatch, ModelState);
            if (!TryValidateModel(touristRouteToPatch))//此处对touristRouteToPatch进行数据校验，不懂。
            {
                return ValidationProblem(ModelState);
            }
            _mapper.Map(touristRouteToPatch, touristRouteFromRepo);//Map的操作依旧不懂，与put一样
            await _touristRouteRepository.SaveAsync();
            return NoContent();

        }

4. [HttpDelete]