Controlling async function in another file

Question

I am calling another function in a file called feedFactory , the function has a asynchronous call, School.findOne , that returns a promise. So the following get postFields value is null since it doesn't wait. How can I control the asynchronous flow from the file that calls the function feedFactory.BuildPostBody ?

const postFields = feedFactory.BuildPostBody(req, res, errorResponse);

And the in the file feedFactory I have the following block of code that returns a promise after I do a query.

      exports = module.exports = {
  BuildPostBody: (req, res, errorResponse) => {
    //Determine what account type we are going to post as using field
    //postToFeedAs
    let postFields;

      case "School":
        {
          //Get industry partner name and company logo
          School.findOne({ _id: req.user.school }).then(school => {
              let avatar =
                "https://image.png";
              if (typeof school.profile.school_logo !== "undefined") {
                avatar = school.profile.school_logo.url;
              }

                  postFields = {
                    author: {
                      userType: req.body.postToFeedAs,
                      user: req.user.school,
                      name: school.name,
                      avatar: avatar
                    },
                    postType: "text",
                    postBody: req.body.postBody
                  };
                  console.log("returning post back from factory");
                  return postFields; <--Returns late 

              ...

Answer 1

You can use Async/await to accomplish your goal:

Put this code into an async function and change to:

const postFields = await feedFactory.BuildPostBody(...)

then when using postFields do

postFields.then(...)