[英]EF Core Entity Post Error with entity that has other entities as properties
情况:
Executed 'ActivitysPost' (Failed, Id=a2e8a556-7b1b-4d0d-995c-65b9c494c802, Duration=26938ms)
[2021-05-03T05:04:29.141Z] System.Private.CoreLib: Exception while executing function: ActivitysPost.
Microsoft.EntityFrameworkCore.Relational: An error occurred while updating the entries.
See the inner exception for details.
Core .Net SqlClient Data Provider:
Cannot insert explicit value for identity column in table 'Helpers'
... when IDENTITY_INSERT is set to OFF.
错误发生在第 2 行:
_context.Add(activity);
await _context.SaveChangesAsync();
使用 EF Core 3.1.14
GitHub 项目(参见 API): https://github.com/djaus2/mslearn-staticwebsite-3entities
注意:以下确实有效(即提交新的助手和回合):
curl --header "Content-Type: application/json" --request POST --data "{'Name':'Recording','Quantity':1,'Round':{'No':1,'Description':'AVSL'},'Helper':{'Name':'FreedyFeelgood','Description':'BlaBlah'}}" http://localhost:7071/api/activitys/
返回结果:
{"id":6,"name":"Recording","quantity":1,"helper":{"id":13,"name":"FreedyFeelgood","description":"BlaBlah"},"round":{"id":7,"no":1,"description":"AVSL"}}
好的,所以查看代码,您遇到的问题是 ef 无法识别作为已在数据库中的实体附加的助手(和回合),而是将它们视为需要创建的新实体。
您可以通过附加从 api 调用反序列化的 Round 和 Helper 来解决此问题。
[FunctionName("ActivitysPost")]
public async Task<IActionResult> Run(
[HttpTrigger(AuthorizationLevel.Anonymous, "post", Route = "activitys")] HttpRequest req,
ILogger log)
{
var body = await new StreamReader(req.Body).ReadToEndAsync();
var activity = JsonConvert.DeserializeObject<Activity>(body);
....
_context.Attach(activity.Helper); // <-- new
_context.Attach(activity.Round); // <-- new
await _context.SaveChangesAsync();
return new OkObjectResult(activity);
}
这告诉 ef 假设它们来自数据库,因此您不需要创建它们。 PUT 方法也会有同样的问题,所以要小心。
希望这可以解决您的问题。
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