使用 .net WebAPI 创建、更新、删除子实体

Question

为了更新实体，我使用 http PUT，将更新后的对象作为请求正文传递：

PUT /api/flareform/3

{
    "JobId" : "12-12-4004",
    "Id" : 3,
    "Tasks" : [
      {
        "Hazard" : "Clumsyness",
        "Id" : 2,
        "FlareFormId" : 3,
        "Task" : "Hammering",
        "Control" : "Make Someone Else Hold the Nail"
      },
      {
        "Hazard" : "Nails",
        "Id" : 3,
        "FlareFormId" : 3,
        "Task" : "Walking",
        "Control" : "Keep area clean."
      }
    ],
    "PercentComplete" : null,
    "Time" : "3pm",
    "Initials" : "JD"
}

如果我更新对象的简单属性（例如 Initials），这将正常工作。是否有可能/如何更新、添加、删除任务。可以通过这个对象吗？我想做的只是传递一个更新的任务数组并让它更新/删除/添加所有内容：

PUT /api/flareform/3

{
    "JobId" : "12-12-4004",
    "Id" : 3,
    "Tasks" : [
      {
        "Hazard" : "NewAndImprovedValue",
        "Id" : 2,
        "FlareFormId" : 3,
        "Task" : "NewAndImprovedValue",
        "Control" : "NewAndImprovedValue"
      },
      {
        "Hazard" : "SomeNewItemThatDidntExistBefore",
        "FlareFormId" : 3,
        "Task" : "NoteTheMissingId",
        "Control" : "ShouldAddThisOne"
      }
    ],
    "PercentComplete" : null,
    "Time" : "3pm",
    "Initials" : "JD"
}

Answer 1

您的 Json 对象看起来不错。我相信罪魁祸首是你的 DAL。因为保存子实体并不像人们想象的那么简单。

我假设您的 Tasks 与主要对象是一对多的关系。如果是这样，您需要手动检测任何更改（添加、删除或修改）并应用它们。

本教程应该可以帮助您入门：http://www.entityframeworktutorial.net/update-one-to-many-entities-in-entity-framework.aspx

Answer 2

这或多或少是我最终使用的。我正在尝试以更通用的方式编写此代码，这样我就不必为每个需要更新的子属性复制/粘贴此代码...

    // PUT api/FlareForm/5
    public HttpResponseMessage PutFlareForm(int id, FlareForm flareform)
    {
        if (!ModelState.IsValid)
        {
            return Request.CreateErrorResponse(HttpStatusCode.BadRequest, ModelState);
        }

        if (id != flareform.Id)
        {
            return Request.CreateResponse(HttpStatusCode.BadRequest);
        }


        List<int> previousIds = db.FlareForms.AsNoTracking().FirstOrDefault(ff => ff.Id == id).Tasks.Select(t => t.Id).ToList();
        List<int> currentIds = flareform.Tasks.Select(t => t.Id).ToList();
        List<int> deletedIds = previousIds
            .Except(currentIds).ToList();


        foreach (var deletedId in deletedIds)
        {
            FlareFormTask task = db.FlareFormTasks
                .Single(od => od.FlareFormId == flareform.Id && od.Id == deletedId);

            db.Entry(task).State = EntityState.Deleted;
        }

        foreach (var task in flareform.Tasks)
        {
            if (task.Id == 0)
            {
                task.FlareFormId = flareform.Id;
                db.Entry(task).State = EntityState.Added;
            }
            else
            {
                db.Entry(task).State = EntityState.Modified;
            }
        }


        db.Entry(flareform).State = EntityState.Modified;

        try
        {
            db.SaveChanges();
        }
        catch (DbUpdateConcurrencyException ex)
        {
            return Request.CreateErrorResponse(HttpStatusCode.NotFound, ex);
        }

        return Request.CreateResponse(HttpStatusCode.OK);
    }