mian mian - 1 month ago 20
Javascript Question

How to retrieve all posts of a user via Facebook Graph API using promises and recursion?

I am currently developing a web app which uses the Facebook Graph API.

What I would like to achieve is to get all posts of a user.

However, this is not that easy since I have to paginate the results.

At the moment I am struggeling with promises.

What I try to achieve is to fill an array with the post objects.

Therefore I use promises and recursion which does not work as expected.

My code currently looks as follows:

// Here I retrieve the user with his or her posts,
// just the first 25 due to pagination
if (accessToken) {
return new Promise(resolve => {
FB.api('/me?fields=id,name,posts&access_token=' + accessToken, response => {
this.get('currentUser').set('content', response);
resolve()
})
})
}

// Returns all posts of a given user
function getAllPostsOfUser(posts, postsArr) {
// Process each post of the current pagination level
for (var post of posts.data) {
// Only store meaningful posts
if (post !== undefined && post.message !== undefined) {
postsArr.push(post)
}
}

// Further posts are retrievalable via paging.next which is an url
if (posts.data.length !== 0 && posts.paging.next !== undefined) {
FB.api(posts.paging.next, response => {
getAllPostsOfUser(response, postsArr)
resolve()
})
}

return postsArr
}

var posts = getAllPostsOfUser(this.get('currentUser').content.posts, [])
// I want to use all the posts here
console.log(posts)


The problem I have is that I want to use the posts where the console.log is placed but when I log the posts array a lot of posts are missing.

I am sure that I did something wrong with the promises but I do not know what.

I would be glad if anyone could guide me to a solution.

Thank you in advance.

Answer

Try this:

function getAllPosts() {
    return new Promise((resolve, reject) => {
        let postsArr = [];
        function recursiveAPICall(apiURL) {
            FB.api(apiURL, response => {
                if (response && response.data) {
                    //add response to posts array (merge arrays), check if there is more data via paging
                    postsArr = postsArr.concat(response.data);
                    if (response.paging && response.paging.next) {
                        recursiveAPICall(response.paging.next);
                    } else {
                        resolve(postsArr);
                    }
                } else {
                    reject();
                }
            })
        }
        recursiveAPICall('/me/posts?fields=message&limit=100');
    }
}

getAllPosts().then(response => {
    console.log(response);
}).catch(e => {
    console.log(e);
});

Not tested, just a quick example i came up with. It returns a promise and uses a recursive function to get all entries. Btw, you donĀ“t need to add the Access Token. If you are logged in, the SDK will use it internally.