How to Effectively Call a POST Request After an AJAX Completion

Discover how to call a POST request after an AJAX upload using promises, ensuring successful image uploads before form submission.
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This video is based on the question https://stackoverflow.com/q/67031203/ asked by the user 'Edama' ( https://stackoverflow.com/u/4464692/ ) and on the answer https://stackoverflow.com/a/67031564/ provided by the user 'Wazeed' ( https://stackoverflow.com/u/6394979/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Effectively Call a POST Request After an AJAX Completion

In the world of web development, asynchronous operations using AJAX can streamline interactions and enhance user experiences. However, this often results in some tricky scenarios, especially when you have to submit forms after successfully uploading images via AJAX. In this guide, we'll explore a common problem faced by many developers: how to ensure that a form submission occurs only after an AJAX upload is complete.

The Problem

Imagine this scenario:

You have two buttons on your web page: one for uploading images via AJAX and another for submitting a form.

Users might click the submit button right after the upload without waiting for the upload action to complete, which can result in failure to store the image on the server.

Here’s a typical log sequence from the console when users act too quickly:

upload start

submit start

As seen, the image upload doesn’t complete before the submission starts, leading to issues where uploaded images aren't stored correctly.

So, how do we solve this and ensure that our form submission waits for the upload to finish?

The Solution

Step 1: Return an AJAX Promise

First, you need to modify your upload function to return a promise. By doing this, you can manage the completion of the AJAX request more effectively. Here’s your modified upload(data) function:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Create a Safe Upload Process

Next, define a new function called safeSubmit(). This function will handle the uploads for any unprocessed image files one after another, thus ensuring that they’re all uploaded before proceeding to submit the form. Here’s how you can implement it:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Attach safeSubmit() to Your Submit Action

Finally, instead of directly calling the submit() function, make sure to link your form submit button to the new safeSubmit() function. This way, when the form is submitted, it will first wait for all the necessary uploads to complete.

Conclusion

By refactoring your JavaScript code to ensure that your AJAX upload returns a promise and designing a safe submission process, you can prevent issues that arise from simultaneous actions. This structured approach not only helps with functionality but also enhances user experience by preventing errors.

Now you can efficiently manage uploads and form submissions, ensuring that your images are stored correctly on the server before proceeding with any other actions.

If you have any questions or need further clarification, feel free to reach out!