Managing Concurrent Updates in Blazor with Entity Framework Core

Описание: Learn how to effectively handle concurrent updates in your Blazor app using Entity Framework Core, ensuring that you always work with the most current data.
---
This video is based on the question https://stackoverflow.com/q/77255741/ asked by the user 'M.M' ( https://stackoverflow.com/u/1505939/ ) and on the answer https://stackoverflow.com/a/77256178/ provided by the user 'Steve Py' ( https://stackoverflow.com/u/423497/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: reading data that may have been updated concurrently

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Managing Concurrent Updates in Blazor with Entity Framework Core

When developing Blazor applications, one common challenge arises: reading data that may have been updated concurrently. This situation is particularly tricky when you need to read rows from a database view, while updates must be performed via stored procedures. In this post, we will explore the implications of this situation and how to ensure that your application consistently retrieves the most current data.

The Problem

In a typical scenario within your Blazor app, you read data from a database using a DbSet<T>. However, since your updates are performed via stored procedures (which may not communicate directly with the DbSet), it raises an important question:

Is it necessary to signal to the DbSet that the underlying data of the view may have changed due to external updates?

During testing, you might notice that calling a stored procedure to update the data, followed by invoking .Where(...).ToListAsync() on the DbSet, retrieves updated changes. This suggests that Entity Framework Core (EFCore) queried the database directly. However, one cannot help but worry that in certain situations, it might instead return values from its internal cache.

The Solution

To ensure that your application works seamlessly when reading potentially updated data, follow these recommendations:

1. Use AsNoTracking()

Utilizing the AsNoTracking() method is a straightforward solution for read operations. This allows the following:

Always Fetch Current Data: It retrieves the most current state of the data from the database, ignoring any entries that might be in the EFCore tracking cache.

Avoids Unintended Caching: With this option enabled, EFCore doesn’t try to cache or track the entities, which minimizes the risk of stale data being presented to your application.

Example Usage:

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

2. Implement Concurrency Tokens

If your application needs to handle updates using both DbSets and external actors (like stored procedures), it's crucial to manage concurrent updates effectively. Here's how:

Use a Concurrency Token: Introduce a concurrency token, such as RowVersion or Timestamp, on the table you are working with. This token acts as a version identifier for your data rows.

Check Before Updating: Before. applying changes via the DbSet, query the concurrency token for the corresponding row:

Compare it against the loaded entity.

If the values differ, that indicates the data has changed since it was first loaded.

Handle Race Conditions: EFCore will automatically reject the update if the concurrency token has changed. This way, you can gracefully handle cases where a change occurs between checking the current state and committing the new state.

Example Implementation:

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

Conclusion

By applying these practices, you can effectively manage concurrent data updates in your Blazor application using Entity Framework Core.

Utilize AsNoTracking() for read operations to always retrieve the latest data.

Incorporate concurrency tokens to safeguard against conflicts when multiple updates occur.

With these strategies in place, you can maintain the integrity and responsiveness of your app, ensuring that users always see the most accurate and up-to-date information from the database.

If this content has helped you address your concerns regarding concurrent updates, feel free to share it with others who might benefit!