Resolving the Issue of ASP.NET Core JSON Object Being Null or Count Zero

Learn how to fix the problem of sending an empty JSON object from your HTML View to your ASP.NET Core Controller, ensuring your data transfers seamlessly.
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Understanding the Problem: Sending JSON Data from View to Controller

In web development, particularly when working with ASP.NET Core MVC, you might encounter a common but frustrating issue: sending a list of values from the View to the Controller can sometimes result in an empty JSON object. This can lead to significant roadblocks, especially when you're trying to collect and process data.

In this guide, we'll explore a scenario where you might be struggling with sending data from an HTML table to your ASP.NET Core controller. We'll provide a clear solution to ensure that your JSON data is correctly formed and passed.

The Initial Setup: Your Code Breakdown

You have a JavaScript function that gathers data from an HTML table and attempts to send it to the server. Below is a simplified breakdown of your JavaScript function:

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

Key Elements of the Code

Event Listener: The button with ID btnSave triggers data collection.

Customer Data Collection: It loops through rows in the HTML table, collecting customer CNIC values.

JSON Conversion: The collected customer data is then converted into a JSON string.

AJAX Submission: The JSON is sent to the server via an AJAX POST request.

However, you noticed that even after making these efforts, the data received by your controller ends up being null or with a count of 0.

The Solution: Making Adjustments to the Code

To resolve the issue of receiving empty or null JSON data, you need to take a few steps to ensure that your data is properly structured and sent.

Step 1: Create a Proper Model

First, define a model that your controller can recognize. In this case, the Customer class should look like this:

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

This model creates a structured representation of the data you aim to send to the server.

Step 2: Update the Controller Action

Your controller action needs to be aware that it's receiving JSON data. To achieve this, include the [FromBody] attribute in the action method parameter. The updated controller action should look like this:

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

This change signals to ASP.NET Core's model binding that the customers parameter is being populated from the HTTP request body, allowing it to deserialize the JSON data into your Customer class.

Conclusion: Testing Your Changes

After implementing these adjustments, test your functionality by clicking the Save button in your HTML view. Monitor the browser console and your server logs to ensure that the data is now being correctly populated and processed.

By structuring your JSON correctly and using model binding with the appropriate attributes, you should no longer encounter empty data issues when sending information from the View to the Controller.

Isn't it great to see your hard work finally pay off? Happy coding!