POST或PUT调用哪个HTTP动词-仅由客户负责吗？

Question

POST方法是否应检查DataStore中是否存在对象并返回错误消息？还是由客户负责检查并调用适当的POST / PUT方法。

当前正在实现-在post方法中检查对象是否存在。

    public HttpResponseMessage Post([FromBody]List<MachineLearningAgentObjectMappingHeader> machineLearningAgentObjectMappingObject)
    {
        string errorString = string.Empty;
        StringBuilder badRequestErrorStrings = new StringBuilder();

        try
        {
            User user = Request.Properties["User"] as User;

            var dal = DalFactory.GetDal();
            var mlAgentRowId = machineLearningAgentObjectMappingObject.FirstOrDefault().MachineLearningAgentRowId;
            var objRowId = machineLearningAgentObjectMappingObject.FirstOrDefault().ObjectRowId;

            var objectMappingsinDb = dal.MachineLearningAgentObjectMapping.GetMachineLearningAgentObjectMappings(machineLearningAgentRowId: mlAgentRowId,objectRowId:objRowId);

            //check if duplicate objectmappings exist
            var duplicatetagMappings = objectMappingsinDb.Where(om => machineLearningAgentObjectMappingObject.Any(item => item.ObjectRowId ==
                om.ObjectRowId && item.MachineLearningAgentRowId == om.MachineLearningAgentRowId)).ToList();

            if (duplicatetagMappings?.Count > 0)
            {
                StringBuilder duplicateEquipmentSetErr = new StringBuilder();
                duplicatetagMappings.ForEach(item => duplicateEquipmentSetErr.AppendLine(string.Format("MachineLearningAgentTagMapping already defined - Object:{0} - MachineLearningAgent:{1}",
                                        item.ObjectId, item.MachineLearningAgentId)));
                return Request.CreateResponse<string>(HttpStatusCode.BadRequest, duplicateEquipmentSetErr.ToString());
            }

            machineLearningAgentObjectMappingObject = dal.MachineLearningAgentObjectMapping.SaveMachineLearningAgentObjectMappings(machineLearningAgentObjectMappingObject, user.RowId.Value);
            return Request.CreateResponse(HttpStatusCode.OK, machineLearningAgentObjectMappingObject);
        }
        catch (Exception ex)
        {
            HandleException(ex);
            return Request.CreateResponse<string>(HttpStatusCode.InternalServerError, ex.Message);
        }
    }