CODEWITHSUNDEEP
vue.jsasync-awaitvuejs2vuex
Floran Gmehlin
Floran Gmehlin

Reputation: 854

Vue.js Non-blocking while statement (polling backend until progress is finished)

Inside a vue action, I want to poll my backend (call another async action like described below? ) until the something has finished processing (frontend shows a loader until progress is over).

In other words, I want to repeatedly make an API call looking like : 

actions: {
    load: async ({dispatch, commit, state}, {args}) => {
    await dispatch('progressPolling', {progressUrl, userId})
    // continue ONLY when progress has finished, else blocks at this statement
    ...
    }

    progressPolling: async ({dispatch, commit}, {progressUrl, userId}) => {
        var finished = false
        while(!finished) : {
            var progress = await dispatch('getResource', {url: progressUrl, userId: userId})
            finished = (progress.data.finished === true)
            // timeout of 2 secs
         }
    }
...
}

My understanding is that that you can use the setTimeout() statement to wait between calls, but am not sure how to turn this into a non-blocking while statement, or simply what is the best practice to achieve this.

EDIT: "Non-blocking" because I was originally using a wait() statement in a while loop. That made the UI freeze each time it had to wait.

Upvotes: 3

Views: 1745

Answers (1)

Shu Yoshioka
Shu Yoshioka

Reputation: 466

I would use recursive function to do this.

progressPolling: async ({dispatch, commit}, {progressUrl, userId}) => {
    // Define a recursive function
    async function getResource (resolve) {
        const progress = await dispatch('getResource', {url: progressUrl, userId: userId})
        // Recurse when not finished
        if (progress.data.finished !== true) {
            setTimeout( () => getResource(resolve), 2000);
        } 
    }
    // Kick the recursive function
    return new Promise (resolve => getResource(resolve))
    // Finished!
}

Upvotes: 2

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