Promise not completing function before going into next

Question

I am writing a promise, where the first part of my promise is doing a git clone in shelljs (node.js app). The second part of the promise is doing a git pull and more. But many times the promise starts the clone and then before that is over, jumps into the function holding other shell.js executions like git pull. But then it does not find the repo. What am I missing here?

My code:

let myPromise = new Promise((rev, err) => {
                    console.log('create promise');
                    rev();
                });

myPromise.then(() => {
                                shell.cd(' ..');
                                shell.cd('git_folder');
                                fs.access('git_repo', function(error) {
                                    if (error) {
                                        console.log("Directory does not exist.")
                                        shell.exec(`git clone the_git_repo && echo "cloned"`);

                                    } else console.log("Directory exists.");
                                })
                            }).then(() => nextFunc());

const nextFunc = () => {
    shell.cd('git_repo');
    shell.exec('git pull');
    //other git commands
}

Sometimes my promise runs in order, and other times, it starts the clone and goes into the nextFunc function but does not find the git_repo folder. Is there anyway to finish the clone and only then execute nextFunc.

Answer 1

The problem is that the main then callback doesn't return a promise, so the promise returned by that then() is immediately resolved, when the fs.access callback hasn't executed yet.

You should have a promise that resolves when access has done its asynchronous task. For that you can use fs.promises: it exposes the same methods (like access) but returning a promise instead of taking a callback.

So that part of the code can be:

myPromise.then(() => {
    shell.cd('..');
    shell.cd('git_folder');
    return fs.promises.access('git_repo');
}).then(() => {
    console.log("Directory exists.");
}).catch(error => {
    console.log("Directory does not exist.");
    shell.exec(`git clone the_git_repo && echo "cloned"`);
}).then(nextFunc);