Query in catch block after reject

Question

I'm working on an application in reactjs that let people publish some post with hashtags, mentions and media. I start saving post in db, after a lot of controls I need to remove the post from DB if some error happen. Here the functions with the promises and the catch block:

        connectDb()
            .then( () => { return savePost() } )
            .then( () => { return postHashtagRoutine() } )
            .then( () => { return iteratePostMedia() } )
            .then( () => { return detectLanguage() } )
            .then( () => { return updatePost() } )
            .then( () => { console.log("pre conn release") } )
            .then( () => { conn.release() } )
            .then( () => { resolve( { success : "done" } )
            .catch( (err) => {
                connectDb()
                    .then( () => { console.log("create post error", err) } )
                    .then( () => { return removePost() } )
                    .then( reject(err) )

            })

Now the problem is that when I call reject in postHashtagRoutine(), if some hashtag contains stopwords, the catch block isn't called and the console log and the removePost() function aren't executed.

Here the code portion where I call the reject in postHashtagRoutine()

     Promise.all(promisesCheckStopwords)
                 .then( () => {
                   if ( stopwordsId.length > 0){
                        reject("stopwordsId in post");
                   }
                 })

Answer 1

You can throw inside a Thenable handler to reject.

A then call will return a rejected promise if the function throws an error or returns a rejected Promise.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/then

I would suggest using throw <result> instead of reject([result]).

For example:

throw "stopwordsId in post"

I'd also suggest you return the second call to connectDb() to ensure that the promise chains are linked together.

If onFulfilled returns a promise, the return value of then will be resolved/rejected by the promise.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/then

First Code Block:

    connectDb()
        .then( () => { return savePost() } )
        .then( () => { return postHashtagRoutine() } )
        .then( () => { return iteratePostMedia() } )
        .then( () => { return detectLanguage() } )
        .then( () => { return updatePost() } )
        .then( () => { console.log("pre conn release") } )
        .then( () => { conn.release() } )
        .then( () => { return { success : "done" } )
        .catch( (err) => {
            return connectDb()
                .then( () => { console.log("create post error", err) } )
                .then( () => { return removePost() } )
                .then( throw err )

        })

Second Code Block:

     Promise.all(promisesCheckStopwords)
             .then( () => {
               if ( stopwordsId.length > 0){
                    throw "stopwordsId in post"
               }
             })