| title | author | description | ms.author | ms.date | no-loc | uid | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Add search to ASP.NET Core Razor Pages |
rick-anderson |
Shows how to add search to ASP.NET Core Razor Pages |
riande |
12/05/2019 |
|
tutorials/razor-pages/search |
::: moniker range=">= aspnetcore-3.0"
In the following sections, searching movies by genre or name is added.
Add the following highlighted properties to Pages/Movies/Index.cshtml.cs:
SearchString: contains the text users enter in the search text box.SearchStringhas the[BindProperty]attribute.[BindProperty]binds form values and query strings with the same name as the property.(SupportsGet = true)is required for binding on GET requests.Genres: contains the list of genres.Genresallows the user to select a genre from the list.SelectListrequiresusing Microsoft.AspNetCore.Mvc.Rendering;MovieGenre: contains the specific genre the user selects (for example, "Western").GenresandMovieGenreare used later in this tutorial.
Update the Index page's OnGetAsync method with the following code:
The first line of the OnGetAsync method creates a LINQ query to select the movies:
// using System.Linq;
var movies = from m in _context.Movie
select m;The query is only defined at this point, it has not been run against the database.
If the SearchString property is not null or empty, the movies query is modified to filter on the search string:
The s => s.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 Where 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 for more information.
Note
The 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, 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, https://localhost:5001/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, https://localhost:5001/Movies/Ghost).
@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.
The ASP.NET Core runtime uses model binding to set the value of the SearchString property from the query string (?searchString=Ghost) or route data (https://localhost:5001/Movies/Ghost). Model binding is not case sensitive.
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 following Tag Helpers:
- Form Tag Helper. When the form is submitted, the filter string is sent to the Pages/Movies/Index page via query string.
- Input Tag Helper
Save the changes and test the filter.
Update the OnGetAsync method with the following code:
The following code is a LINQ query that retrieves all the genres from the database.
The SelectList of genres is created by projecting the distinct genres.
Update Index.cshtml as follows:
Test the app by searching by genre, by movie title, and by both.
[!div class="step-by-step"] Previous: Updating the pages Next: Adding a new field
::: moniker-end
::: moniker range="< aspnetcore-3.0"
In the following sections, searching movies by genre or name is added.
Add the following highlighted properties to Pages/Movies/Index.cshtml.cs:
SearchString: contains the text users enter in the search text box.SearchStringhas the[BindProperty]attribute.[BindProperty]binds form values and query strings with the same name as the property.(SupportsGet = true)is required for binding on GET requests.Genres: contains the list of genres.Genresallows the user to select a genre from the list.SelectListrequiresusing Microsoft.AspNetCore.Mvc.Rendering;MovieGenre: contains the specific genre the user selects (for example, "Western").GenresandMovieGenreare used later in this tutorial.
Update the Index page's OnGetAsync method with the following code:
The first line of the OnGetAsync method creates a LINQ query to select the movies:
// using System.Linq;
var movies = from m in _context.Movie
select m;The query is only defined at this point, it has not been run against the database.
If the SearchString property is not null or empty, the movies query is modified to filter on the search string:
The s => s.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 Where 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 for more information.
Note: The 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, 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, https://localhost:5001/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, https://localhost:5001/Movies/Ghost).
@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.
The ASP.NET Core runtime uses model binding to set the value of the SearchString property from the query string (?searchString=Ghost) or route data (https://localhost:5001/Movies/Ghost). Model binding is not case sensitive.
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 following Tag Helpers:
- Form Tag Helper. When the form is submitted, the filter string is sent to the Pages/Movies/Index page via query string.
- Input Tag Helper
Save the changes and test the filter.
Update the OnGetAsync method with the following code:
The following code is a LINQ query that retrieves all the genres from the database.
The SelectList of genres is created by projecting the distinct genres.
Update Index.cshtml as follows:
Test the app by searching by genre, by movie title, and by both. The preceding code uses the Select Tag Helper and Option Tag Helper.
[!div class="step-by-step"] Previous: Updating the pages Next: Adding a new field
::: moniker-end