Angular 中的关系（错误 400 - 错误请求）

Question

I have quite a big problem with adding data to the table connected with the Spring database. Namely, just adding to the table works fine, only when I don't choose anything from the Combo Box. When I choose, I get this message:

zone-evergreen.js:2952 POST http://localhost:4200/api/cars 400 (Bad Request)

HttpErrorResponse {headers: HttpHeaders, status: 400, statusText: "Bad Request", url: "http://localhost:4200/api/cars", ok: false, …}

I am aware that this is a problem with the link and most likely with a relationship, but I have no idea how to solve this problem. My models look like this:

http-cars.model.ts

export class carStatus {
  id: number;
  name: string;
}

//carStatus.model.ts (TypeScript)

export class carType {
  id: number;
  name: string;
}

//carType.model.ts (TypeScript)

To better understand the problem, I will give services and the vehicle adding component (if you need more files, please write):

add-dialog1.component.ts

http-cars.service.ts

car-status.service.ts (carType has the same service only with changed variables and names)

config.service.ts (all included functions link to a link from proxy.conf.json)

{
  "/api": {
    "target": "xxx(link)",
    "secure": false,
    "changeOrigin": true,
    "logLevel": "debug"
  }

}

And finally HTML:

add-dialog1.component.html

If anyone has an idea why adding data without using a combo box works fine, and if I choose something from these two combo boxes (or one of them) the above error appears, please write what I made the error and how I can solve it. Buddy responsible for Spring said that everything is fine on his part and when he sends data via Postman it works for him, but in my table in combobox columns shows "[object object]". here is an example of a query and part of my table:

Postman Query

Part of table

Please be forgiving. This is my second question and I have no experience asking questions here, and I am mostly looking for answers on this page. If I did something incompatible with your netiquette, please let me know. I can't find any solution to the problem and what I tried didn't work and I need help.

Answer 1

I would start by looking at the information available in the "network" tab, usually in the console window or menu of your browser.

Second, I would attempt to issue the command to the backend using a curl command. The ability to do that would tell you whether the problem is in your frontend or backend or http command.