我已经创建了一个WebAPI项目,该项目在使用DELETE和GET方法时可以正常工作,但是当我尝试POST或PUT时,我会收到
第84行上的{“值不能为null。\ r \ n参数名称:实体”},db.Reviews.Add(review)
我正在使用Postman进行测试,也尝试使用XMLHttpRequest,但是这两种方法都可以在GET / DELETE上运行,而在PUT / POST上失败。
var update1 = new XMLHttpRequest();
var params = "ReviewID=123";
update1.open("POST", "http://localhost:49681/Api/Reviews/", true);
update1.setRequestHeader("Content-type", "application/json");
update1.send(params);
ReviewsController
using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Entity;
using System.Data.Entity.Infrastructure;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Threading.Tasks;
using System.Web.Http;
using System.Web.Http.Description;
using ReviewApp.Models;
namespace ReviewApp.Controllers
{
public class ReviewsController : ApiController
{
private CheetahEntities db = new CheetahEntities();
// GET: api/Reviews
public IQueryable<Review> GetReviews()
{
return db.Reviews;
}
// GET: api/Reviews/5
[ResponseType(typeof(Review))]
public async Task<IHttpActionResult> GetReview(string id)
{
Review review = await db.Reviews.FindAsync(id);
if (review == null)
{
return NotFound();
}
return Ok(review);
}
// PUT: api/Reviews/5
[ResponseType(typeof(void))]
public async Task<IHttpActionResult> PutReview(string id, Review review)
{
if (!ModelState.IsValid)
{
return BadRequest(ModelState);
}
if (id != review.ReviewID)
{
return BadRequest();
}
db.Entry(review).State = EntityState.Modified;
try
{
await db.SaveChangesAsync();
}
catch (DbUpdateConcurrencyException)
{
if (!ReviewExists(id))
{
return NotFound();
}
else
{
throw;
}
}
return StatusCode(HttpStatusCode.NoContent);
}
// POST: api/Reviews
[ResponseType(typeof(Review))]
public async Task<IHttpActionResult> PostReview(Review review)
{
/*
if (!ModelState.IsValid)
{
return BadRequest(ModelState);
}
*/
db.Reviews.Add(review);
try
{
await db.SaveChangesAsync();
}
catch (DbUpdateException)
{
if (ReviewExists(review.ReviewID))
{
return Conflict();
}
else
{
throw;
}
}
return CreatedAtRoute("DefaultApi", new { id = review.ReviewID }, review);
}
// DELETE: api/Reviews/5
[ResponseType(typeof(Review))]
public async Task<IHttpActionResult> DeleteReview(string id)
{
Review review = await db.Reviews.FindAsync(id);
if (review == null)
{
return NotFound();
}
db.Reviews.Remove(review);
await db.SaveChangesAsync();
return Ok(review);
}
protected override void Dispose(bool disposing)
{
if (disposing)
{
db.Dispose();
}
base.Dispose(disposing);
}
private bool ReviewExists(string id)
{
return db.Reviews.Count(e => e.ReviewID == id) > 0;
}
}
}
审查
//------------------------------------------------------------------------------
// <auto-generated>
// This code was generated from a template.
//
// Manual changes to this file may cause unexpected behavior in your application.
// Manual changes to this file will be overwritten if the code is regenerated.
// </auto-generated>
//------------------------------------------------------------------------------
namespace ReviewApp.Models
{
using System;
using System.Collections.Generic;
public partial class Review
{
public string ReviewID { get; set; }
public string ReviewStatus { get; set; }
public Nullable<System.DateTime> Date { get; set; }
public string Account { get; set; }
}
}
猎豹实体
//------------------------------------------------------------------------------
// <auto-generated>
// This code was generated from a template.
//
// Manual changes to this file may cause unexpected behavior in your application.
// Manual changes to this file will be overwritten if the code is regenerated.
// </auto-generated>
//------------------------------------------------------------------------------
namespace ReviewApp.Models
{
using System;
using System.Data.Entity;
using System.Data.Entity.Infrastructure;
public partial class CheetahEntities : DbContext
{
public CheetahEntities()
: base("name=CheetahEntities")
{
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
throw new UnintentionalCodeFirstException();
}
public virtual DbSet<Review> Reviews { get; set; }
}
}
在请求你的内容类型application/json
,但送你params
跟ReviewId=123
这不是JSON。params
如果以的形式发送Content-Type
,则应使用格式正确的JSON对象application/json
。
var update1 = new XMLHttpRequest();
var params = JSON.stringify({ ReviewID : 123 }); //JSON payload
update1.open("POST", "http://localhost:49681/Api/Reviews/", true);
update1.setRequestHeader("Content-type", "application/json");
update1.send(params);
在你的PostReview
方法没有为潜在的review
变量是null
,如果该POST
请求未正确发送,但出现了试图将其添加到数据库之前不变量的检查。您已注释掉模型上的验证检查。
// POST: api/Reviews
[ResponseType(typeof(Review))]
public async Task<IHttpActionResult> PostReview(Review review) {
if (review == null) ModelState.AddModelError("", "invalid data");
if (!ModelState.IsValid) {
return BadRequest(ModelState);
}
db.Reviews.Add(review);
try {
await db.SaveChangesAsync();
} catch (DbUpdateException) {
if (ReviewExists(review.ReviewID)) {
return Conflict();
} else {
throw;
}
}
return CreatedAtRoute("DefaultApi", new { id = review.ReviewID }, review);
}
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