使用参数MongoDB NodeJS删除请求

Question

I try to send delete request from Angular 4 to mongoDb

I have an array of ids, which I want to delete and in my service I have a function

  deleteData(id) {
    return this.http.delete( this.api, id)
  }

Then in my component I build an array of objects (because I need to pass it to backend as JSON - as an array it won't be probably recognised)

  deleteData(data) {
    const dataToSend = [];
    let oneDataToSend;

    for (let i = 0; i < data.length; i++) {
      oneDataToSend = {'_id': ''};
      oneDataToSend._id = data[i];
      dataToSend.push(oneDataToSend);
    }
    this.service.deleteData(dataToSend).subscribe((res) => {
      console.log(data);
    });
  }

And after that I try to delete objects, which ids are the same as in a query

app.delete('/tasks', function(req,res){
  console.log(req.body);
  var ids = [];
  for (let i = 0; i < req.body.length; i ++) {
    ids.push(req.body[i]._id);
  }
  var myquery = { _id: { $in: ids } };
  Model.collection.deleteMany(myquery, function(err, obj) {
    if (err) throw err;
  });
});

Here I got the problem, that there req.body is empty {} Also, in console in Network section I see 2 requests OPTIONS (with Status Code 204 No Content) DELETE without any info

Could you please give me a hint and help to solve this problem?

Answer 1

The reason you see the OPTIONS request with a 204 NO CONTENT response is because of Cross Origin Resource Sharing (CORS). The client is checking if it is allowed to make a DELETE request to your backend.

Consider allowing CORS in the backend application. For an easy way for express, use expressjs/cors . However, make sure you understand the security implications of allowing cross-site requests.

Also, are you parsing the request body? If not, it will be undefined in req.body.

You can use express.json() , it will attempt to parse the JSON of the request body and save it to req.body, but only if the header "Content-Type: application/json" is sent along with the request:

const app = express();
app.use(express.json()); // Parses request body if type is json. Saves to req.body.