The `s => s.Title.Contains()` code is a [Lambda Expression](/dotnet/csharp/programming-guide/statements-expressions-operators/lambda-expressions). Lambdas are used in method-based [LINQ](/dotnet/csharp/programming-guide/concepts/linq/) queries as arguments to standard query operator methods such as the [Where](/dotnet/csharp/programming-guide/concepts/linq/query-syntax-and-method-syntax-in-linq) method or `Contains` (used in the preceding code). LINQ queries are not executed when they're defined or when they're modified by calling a method (such as `Where`, `Contains` or `OrderBy`). Rather, query execution is deferred. That means the evaluation of an expression is delayed until its realized value is iterated over or the `ToListAsync` method is called. See [Query Execution](/dotnet/framework/data/adonet/ef/language-reference/query-execution) for more information.
**Note:** The [Contains](/dotnet/api/system.data.objects.dataclasses.entitycollection-1.contains) method is run on the database, not in the C# code. The case sensitivity on the query depends on the database and the collation. On SQL Server, `Contains` maps to [SQL LIKE](/sql/t-sql/language-elements/like-transact-sql), which is case insensitive. In SQLite, with the default collation, it's case sensitive.
Navigate to the Movies page and append a query string such as `?searchString=Ghost` to the URL (for example, `http://localhost:5000/Movies?searchString=Ghost`). The filtered movies are displayed.
If the following route template is added to the Index page, the search string can be passed as a URL segment (for example, `http://localhost:5000/Movies/ghost`).
```cshtml
@page "{searchString?}"
```
The preceding route constraint allows searching the title as route data (a URL segment) instead of as a query string value. The `?` in `"{searchString?}"` means this is an optional route parameter.
However, you can't expect users to modify the URL to search for a movie. In this step, UI is added to filter movies. If you added the route constraint `"{searchString?}"`, remove it.
Open the *Pages/Movies/Index.cshtml* file, and add the `<form>` markup highlighted in the following code:
The HTML `<form>` tag uses the [Form Tag Helper](xref:mvc/views/working-with-forms#the-form-tag-helper). When the form is submitted, the filter string is sent to the *Pages/Movies/Index* page. Save the changes and test the filter.
Tag snippet_selectlist's start line '75' should be less than end line '29' when resolving "[!code-csharp[](../../tutorials/razor-pages/razor-pages-start/sample/RazorPagesMovie/Pages/Movies/Index.cshtml.cs?name=snippet_SelectList)]"
