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guardrex merged 4 commits into from
Jul 30, 2025
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SQLite guidance for case insensitive filtering #35853

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SQLite workaround for case insensitive filtering
guardrex Jul 29, 2025
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Update aspnetcore/blazor/tutorials/movie-database-app/part-6.md
guardrex Jul 29, 2025
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guardrex Jul 30, 2025
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Update aspnetcore/blazor/tutorials/movie-database-app/part-6.md
guardrex Jul 30, 2025
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16 changes: 11 additions & 5 deletions aspnetcore/blazor/tutorials/movie-database-app/part-6.md
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Expand Up @@ -58,7 +58,16 @@ Change the `QuickGrid` component's <xref:Microsoft.AspNetCore.Components.QuickGr

The `movie => movie.Title!.Contains(...)` code is a *lambda expression*. Lambdas are used in method-based LINQ queries as arguments to standard query operator methods such as the <xref:System.Linq.Queryable.Where%2A> or <xref:System.String.Contains%2A> methods. LINQ queries aren't executed when they're defined or when they're modified by calling a method, such as <xref:System.Linq.Queryable.Where%2A>, <xref:System.String.Contains%2A>, or <xref:System.Linq.Queryable.OrderBy%2A>. Rather, query execution is deferred. The evaluation of an expression is delayed until its realized value is iterated.

The <xref:System.Data.Objects.DataClasses.EntityCollection%601.Contains%2A> method is run on the database, not in the C# code. The case sensitivity of the query depends on the database and the collation. For SQL Server, <xref:System.String.Contains%2A> maps to [SQL `LIKE`](/sql/t-sql/language-elements/like-transact-sql), which is case insensitive. SQLite with default collation provides a mixture of case sensitive and case insensitive filtering, depending on the query. For information on making case insensitive SQLite queries, see the [Additional resources](#additional-resources) section of this article.
The <xref:System.Data.Objects.DataClasses.EntityCollection%601.Contains%2A> method is run on the database, not in the C# code. The case sensitivity of the query depends on the database and the collation. For SQL Server, <xref:System.String.Contains%2A> maps to [SQL `LIKE`](/sql/t-sql/language-elements/like-transact-sql), which is case insensitive. SQLite with default collation provides a mixture of case-sensitive and case-insensitive filtering, depending on the query. The remainder of this tutorial assumes case-insensitive database collation.

To adopt case-insensitive collation when using SQLite (<xref:Microsoft.EntityFrameworkCore.SqliteDbContextOptionsBuilderExtensions.UseSqlite%2A> is called in `Program.cs`), open the `Data/BlazorWebAppMoviesContext.cs` file. Inside the `BlazorWebAppMoviesContext` class, add the following code:

```csharp
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.UseCollation("SQL_Latin1_General_CP1_CS_AS");
}
```
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@AndriySvyryd AndriySvyryd Jul 31, 2025

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This is incorrect on multiple levels. But crucially EF translates Contains to instr on SQLite and that always performs a case sensitive comparison independently of the collation. The correct solution is to call ToLower first.

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@guardrex guardrex Jul 31, 2025 •
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Don't reply here ... let's move the discussion to #35868.

I see. Where is this covered in EF Core docs because ...

https://learn.microsoft.com/en-us/ef/core/miscellaneous/collations-and-case-sensitivity

... isn't a good cross-link for this particular scenario, namely SQLite and case sensitivity.

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@guardrex guardrex Jul 31, 2025 •
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Don't reply here ... let's move the discussion to #35868.

BTW @AndriySvyryd ... It hasn't gone live, so you did catch it in time. Thanks for jumping on to let me know. I'll fix it right now.

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@guardrex guardrex Jul 31, 2025 •
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Don't reply here ... let's move the discussion to #35868.

I'm looking back over the earlier remarks, and there seems to be disagreement ...

SQLite allows you to define collations on the column level - that's the thing to show (so basically this) with NOCASE).

... versus ...

The correct solution is to call ToLower first.

So ... will the following work?

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    modelBuilder.Entity<Movie>().Property(c => c.Title).UseCollation("NOCASE");
}

If it's unclear, I'll test it, but I'll do so in the morning. I'm just about at 🛌💤🐑🐑🐑 time.

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@guardrex guardrex Jul 31, 2025

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Let's take it up on the PR. I'll start with @roji, and then I have a feeling that we'll be moving to @AndriySvyryd over there.

#35868


Run the app and navigate to the movies `Index` page at `/movies`. The movies in the database load:

Expand Down Expand Up @@ -143,10 +152,7 @@ Stop the app by closing the browser's window and pressing <kbd>Ctrl</kbd>+<kbd>C
* [LINQ documentation](/dotnet/csharp/programming-guide/concepts/linq/)
* [Write C# LINQ queries to query data (C# documentation)](/dotnet/csharp/programming-guide/concepts/linq/query-syntax-and-method-syntax-in-linq)
* [Lambda Expression (C# documentation](/dotnet/csharp/programming-guide/statements-expressions-operators/lambda-expressions)
* Case insensitive SQLite queries
* [How to use case-insensitive query with Sqlite provider? (`dotnet/efcore` #11414)](https://github.com/dotnet/efcore/issues/11414)
* [How to make a SQLite column case insensitive (`dotnet/AspNetCore.Docs` #22314)](https://github.com/dotnet/AspNetCore.Docs/issues/22314)
* [Collations and Case Sensitivity](/ef/core/miscellaneous/collations-and-case-sensitivity)
* [Collations and Case Sensitivity](/ef/core/miscellaneous/collations-and-case-sensitivity)

## Legal

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