Firebase 云功能：等到request.body有效再更新

Question

I'm having some frustration with Cloud Functions accessed via my webGL Unity app. I am getting 2 requests instead of one, and the first one is always undefined. Therefore my database is adding 2 elements to my array which each call, one completely empty, and one valid.

Here is my cloud function, which works perfectly when tested from Unity, but not when run from my hosted site.

export const addSavedMission = functions.https.onRequest(
    (request, response) => {
    response.set(
      "Access-Control-Allow-Origin",
      "https://myunity.web.app"
    );
    response.set("Access-Control-Allow-Headers", "*");
    response.set("Accept", "application/json");

    // update the array data
    admin
      .firestore()
      .doc("data/missionData")
      .update({
        missions: admin.firestore.FieldValue.arrayUnion(request.body),
      })
      .then(() => {
        response.status(200).json({ message: `Success` });
      })
      .catch((error) => {
        console.error(error);
        response.status(500).json({
          message: error,
        });
      });
});

And here is my Unity code which calls it

IEnumerator PostSavedData()
{
    string data = JsonUtility.ToJson(thisMission);

    string url = $"https://us-central1-app.cloudfunctions.net/addSavedMission";
    var request = new UnityWebRequest(url, "POST");
    byte[] bodyRaw = Encoding.UTF8.GetBytes(data);
    request.uploadHandler = new UploadHandlerRaw(bodyRaw);
    request.downloadHandler = new DownloadHandlerBuffer();

    request.SetRequestHeader("Access-Control-Allow-Methods", "POST");
    request.SetRequestHeader("Content-Type", "application/json");
    request.SetRequestHeader("Access-Control-Allow-Headers", "*");
    request.SetRequestHeader("Access-Control-Allow-Origin", "https://myunity.web.app");

    yield return request.SendWebRequest();
    if (request.isNetworkError)
    {
        Debug.Log("Error: " + request.error);
    }
    else
    {
        Debug.Log("Status Code: " + request.responseCode);           
    }

}

When I hit this POST request from my hosted app, I log out the incoming request.rawBody, and the first is always undefined, but the second one is valid.

What am I missing here? I'm sure there is 2 incoming requests from 1 POST.

I've tried checking to see if request.rawBody,== undefined, and only if it is not handling the firestore update but then it just never processes the 2nd valid request

Answer 1

The first request is probably a cors pre-flight request . It will not contain the actual data of the request. It's just required by the cors protocol.

Managing cors will be easier if you use the nodejs cors module in your Cloud Function so that it automatically handles the first request.

const cors = require('cors')({origin: true});

export const addSavedMission = functions.https.onRequest(
    (request, response) => {
    cors(request, response, () => {
        // your function code here
    })
});