解析云代码-等待并返回关系查询

Question

so I'm trying to get this cloud query function to run. Basically, I would like to get return the profile by its ID. Then using that result object, run a relation query and return the first result.

I'm not sure if I'm getting mixed up but I'm struggling on awaiting for the full query to finish before returning.

Thanks

Parse.Cloud.define("getLastWeightForAnimal", async (request) => {

try {

    var AnimalProfiles = Parse.Object.extend("animal_profiles");
    var query = new Parse.Query(AnimalProfiles);

    query.get(request.params.id).then((animalProfile) => {

        var AnimalWeights = animalProfile.relation("weights").query();

        AnimalWeights.descending("createdAt");

        let result = await AnimalWeights.first();
        return result;

    }, (error) => {
      // The object was not retrieved successfully.
      // error is a Parse.Error with an error code and message.
        console.log("Uh Oh Inner");
        console.log("Error Inner: "+  error);
    });

} catch (e) {
    console.log("Uh Oh");
    console.log("Error: "+  e);
}


});

Answer 1

If you return inside of a promise .then(function(){return 'a'}) the return 'a' does not return the async (request)` !

If you do

Promise.resolve()
  .then(function(){return 'a'}) // this 'a' does not go to any parent function!
  .then(function(val){console.log(val)}) // it goes here!

you would see 'a' in your log, as a simple illustration.

You can switch it to async/await

Parse.Cloud.define("getLastWeightForAnimal", async (request) => {

  try {

    var AnimalProfiles = Parse.Object.extend("animal_profiles");
    var query = new Parse.Query(AnimalProfiles);

    var animalProfile = await query.get(request.params.id)

    var AnimalWeights = animalProfile.relation("weights").query();

    AnimalWeights.descending("createdAt");

    let result = await AnimalWeights.first();
    return result;

  } catch (e) {
    console.log("Uh Oh");
    console.log("Error: "+  e);
  }


});

OR simply return the promise, which since you're using async will automatically return the value of the promise.

Parse.Cloud.define("getLastWeightForAnimal", async (request) => {

  try {

    var AnimalProfiles = Parse.Object.extend("animal_profiles");
    var query = new Parse.Query(AnimalProfiles);

    // note new return!!
    return query.get(request.params.id).then((animalProfile) => {

        var AnimalWeights = animalProfile.relation("weights").query();

        AnimalWeights.descending("createdAt");

        let result = await AnimalWeights.first();
        return result;

    }, (error) => {
      // The object was not retrieved successfully.
      // error is a Parse.Error with an error code and message.
        console.log("Uh Oh Inner");
        console.log("Error Inner: "+  error);
    });

  } catch (e) {
    console.log("Uh Oh");
    console.log("Error: "+  e);
  }


});