Скачать или смотреть How to Fix the Issue of Angular Material Table Not Showing Values

Discover why your Angular Material table is not displaying values and learn how to solve it with simple steps.
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This video is based on the question https://stackoverflow.com/q/67085390/ asked by the user 'Andy' ( https://stackoverflow.com/u/15260502/ ) and on the answer https://stackoverflow.com/a/67085708/ provided by the user 'Umaiz Khan' ( https://stackoverflow.com/u/8825698/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Fix the Issue of Angular Material Table Not Showing Values: A Step-by-Step Guide

In Angular development, you may encounter situations where data doesn't appear in a mat-table component, even though it displays correctly in other components. If you've found yourself in this frustrating scenario, you're not alone! Let's explore the potential reasons behind this problem and, more importantly, how to fix it.

Understanding the Problem

You might be trying to display a list of items in a table, similar to the following:

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

While the above setup can display information correctly using mat-accordion, you are encountering issues when implementing a mat-table.

Common Symptoms

The table displays correctly without errors, but data is missing in the rows.

Data appears successfully in other elements (like the accordion) but not in the table.

Solution: Step-by-Step Guide

The solution to your problem lies in making sure that the table is defined correctly and that required properties are set for displaying columns. Here's how to do it:

1. Define displayedColumns

In your corresponding TypeScript file (e.g., component.ts), define an array to specify which columns you want to display:

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

This line of code indicates that four columns, namely name, company, type, and quantity, will be displayed in the table.

2. Set Up Table Rows

In your HTML file, you need to add two key elements to set up the header and data rows within your mat-table. Here’s what you need to include:

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

Here's how this works:

The <tr mat-header-row *matHeaderRowDef="displayedColumns"></tr> line creates the header row using the columns defined in the displayedColumns array.

The <tr mat-row *matRowDef="let row; columns: displayedColumns;"></tr> line renders the actual data rows based on the same column definitions.

3. Confirming Data Availability

Ensure that the posts array contains data. If this array is empty, no records will be displayed in the table. Additionally, consider displaying a message if no records are available:

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

Conclusion

By following these steps, you should be able to resolve the issue of your Angular Material table not displaying values correctly. The key components to check include:

The definition of the displayedColumns in your TypeScript file.

Proper rows setup for both headers and data in the HTML template.

If issues persist, consult the Angular Material documentation for further assistance, as it can provide insightful examples and guidelines. Happy coding!