Скачать или смотреть How to Store a List of Objects in MongoDB with C# and Blazor Server

Learn how to properly store and retrieve lists of objects in MongoDB using C# .NET 7 and Blazor Server—overcoming common errors and misconceptions.
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How to Store a List of Objects in MongoDB with C# and Blazor Server: A Complete Guide

When working with MongoDB in a C# .NET 7 and Blazor Server application, you may encounter some challenges when trying to store a list of objects. One common issue involves a property, such as Transcript, being incorrectly stored as an object instead of a list. This post will walk through this problem, provide an explanation, and offer practical solutions.

Understanding the Problem

The issue arises when you're trying to store a list of objects within a field in your MongoDB document. For instance, in your AllUser class, you have a Transcript property that is meant to hold a list of transcript entries. However, an error occurs if this property is not correctly defined or instantiated.

Error Example

You might see an error message like this:

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

This indicates that the Transcript field is stored as a document {} instead of an expected array []. This mismatch leads to deserialization issues when you try to retrieve or manipulate the data.

Solution Steps

To resolve this issue, follow these steps:

1. Properly Define the Transcript Property

Make sure your Transcript property in the AllUser class is correctly defined as a List<Transcript>. Here’s the relevant portion of the AllUser class:

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

2. Initialize Your List

When you instantiate your AllUser object, ensure that the Transcript list is initialized:

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

3. Update Logic for Storing Data

In your data saving logic (for example, in your function that updates the user), ensure you append transcripts to the existing list rather than replacing it:

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

4. Verify Data Structure in MongoDB

Before storing data, confirm that the database structure aligns with your expectations. You should see the Transcript field in MongoDB documents as an array:

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

5. Testing and Debugging

After implementing these adjustments, thoroughly test your application. Perform CRUD (Create, Read, Update, Delete) operations on the Transcript to ensure it's functioning correctly without throwing any errors.

Conclusion

Storing and retrieving a list of objects in MongoDB using C# .NET 7 and Blazor Server can be complex, but understanding the data structure requirements and properly setting up your classes helps overcome common hurdles. By following the guide above, you should now be able to effectively manage lists of objects in your application.

If you found this guide helpful, feel free to share it with others who may encounter the same challenges in their development process!