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title	author	description	monikerRange	ms.author	ms.date	uid
Razor Pages route and app conventions in ASP.NET Core	guardrex	Discover how route and app model provider conventions help you control page routing, discovery, and processing.	>= aspnetcore-2.0	riande	10/12/2018	razor-pages/razor-pages-conventions

Razor Pages route and app conventions in ASP.NET Core

By Luke Latham

Learn how to use page route and app model provider conventions to control page routing, discovery, and processing in Razor Pages apps.

When you need to configure custom page routes for individual pages, configure routing to pages with the AddPageRoute convention described later in this topic.

To specify a page route, add route segments, or add parameters to a route, use the page's @page directive. For more information, see Custom routes.

There are reserved words that can't be used as route segments or parameter names. For more information, see Routing: Reserved routing names.

View or download sample code (how to download)

::: moniker range="= aspnetcore-2.0"

Scenario	The sample demonstrates ...
Model conventions Conventions.Add IPageRouteModelConvention IPageApplicationModelConvention	Add a route template and header to an app's pages.
Page route action conventions AddFolderRouteModelConvention AddPageRouteModelConvention AddPageRoute	Add a route template to pages in a folder and to a single page.
Page model action conventions AddFolderApplicationModelConvention AddPageApplicationModelConvention ConfigureFilter (filter class, lambda expression, or filter factory)	Add a header to pages in a folder, add a header to a single page, and configure a filter factory to add a header to an app's pages.
Default page app model provider	Replace the default page model provider to change the conventions for handler names.

::: moniker-end

::: moniker range=">= aspnetcore-2.1"

Scenario	The sample demonstrates ...
Model conventions Conventions.Add IPageRouteModelConvention IPageApplicationModelConvention IPageHandlerModelConvention	Add a route template and header to an app's pages.
Page route action conventions AddFolderRouteModelConvention AddPageRouteModelConvention AddPageRoute	Add a route template to pages in a folder and to a single page.
Page model action conventions AddFolderApplicationModelConvention AddPageApplicationModelConvention ConfigureFilter (filter class, lambda expression, or filter factory)	Add a header to pages in a folder, add a header to a single page, and configure a filter factory to add a header to an app's pages.
Default page app model provider	Replace the default page model provider to change the conventions for handler names.

::: moniker-end

Razor Pages conventions are added and configured using the AddRazorPagesOptions extension method to AddMvc on the service collection in the Startup class. The following convention examples are explained later in this topic:

public void ConfigureServices(IServiceCollection services)
{
    services.AddMvc()
        .AddRazorPagesOptions(options =>
            {
                options.Conventions.Add( ... );
                options.Conventions.AddFolderRouteModelConvention("/OtherPages", model => { ... });
                options.Conventions.AddPageRouteModelConvention("/About", model => { ... });
                options.Conventions.AddPageRoute("/Contact", "TheContactPage/{text?}");
                options.Conventions.AddFolderApplicationModelConvention("/OtherPages", model => { ... });
                options.Conventions.AddPageApplicationModelConvention("/About", model => { ... });
                options.Conventions.ConfigureFilter(model => { ... });
                options.Conventions.ConfigureFilter( ... );
            });
}

Route order

Routes specify an xref:Microsoft.AspNetCore.Mvc.ApplicationModels.AttributeRouteModel.Order* for processing (route matching).

Order	Behavior
-1	The route is processed before other routes are processed.
0	Order isn't specified (default value). Not assigning `Order` (`Order = null`) defaults the route `Order` to 0 (zero) for processing.
1, 2, … n	Specifies the route processing order.

Route processing is established by convention:

Routes are processed in sequential order (-1, 0, 1, 2, … n).
When routes have the same Order, the most specific route is matched first followed by less specific routes.
When routes with the same Order and the same number of parameters match a request URL, routes are processed in the order that they're added to the xref:Microsoft.AspNetCore.Mvc.ApplicationModels.PageConventionCollection.

If possible, avoid depending on an established route processing order. Generally, routing selects the correct route with URL matching. If you must set route Order properties to route requests correctly, the app's routing scheme is probably confusing to clients and fragile to maintain. Seek to simplify the app's routing scheme. The sample app requires an explicit route processing order to demonstrate several routing scenarios using a single app. However, you should attempt to avoid the practice of setting route Order in production apps.

Razor Pages routing and MVC controller routing share an implementation. Information on route order in the MVC topics is available at Routing to controller actions: Ordering attribute routes.

Model conventions

Add a delegate for IPageConvention to add model conventions that apply to Razor Pages.

Add a route model convention to all pages

Use Conventions to create and add an IPageRouteModelConvention to the collection of IPageConvention instances that are applied during page route model construction.

The sample app adds a {globalTemplate?} route template to all of the pages in the app:

[!code-csharp]

A route template for TheContactPage/{text?} is added later in the topic. The Contact Page route has a default order of null (Order = 0), so it matches before the {globalTemplate?} route template.
An {aboutTemplate?} route template is added later in the topic. The {aboutTemplate?} template is given an Order of 2. When the About page is requested at /About/RouteDataValue, "RouteDataValue" is loaded into RouteData.Values["globalTemplate"] (Order = 1) and not RouteData.Values["aboutTemplate"] (Order = 2) due to setting the Order property.
An {otherPagesTemplate?} route template is added later in the topic. The {otherPagesTemplate?} template is given an Order of 2. When any page in the Pages/OtherPages folder is requested with a route parameter (for example, /OtherPages/Page1/RouteDataValue), "RouteDataValue" is loaded into RouteData.Values["globalTemplate"] (Order = 1) and not RouteData.Values["otherPagesTemplate"] (Order = 2) due to setting the Order property.

Wherever possible, don't set the Order, which results in Order = 0. Rely on routing to select the correct route.

Razor Pages options, such as adding Conventions, are added when MVC is added to the service collection in Startup.ConfigureServices. For an example, see the sample app.

[!code-csharp]

Request the sample's About page at localhost:5000/About/GlobalRouteValue and inspect the result:

Add an app model convention to all pages

Use Conventions to create and add an IPageApplicationModelConvention to the collection of IPageConvention instances that are applied during page app model construction.

To demonstrate this and other conventions later in the topic, the sample app includes an AddHeaderAttribute class. The class constructor accepts a name string and a values string array. These values are used in its OnResultExecuting method to set a response header. The full class is shown in the Page model action conventions section later in the topic.

The sample app uses the AddHeaderAttribute class to add a header, GlobalHeader, to all of the pages in the app:

[!code-csharp]

Startup.cs:

[!code-csharp]

Request the sample's About page at localhost:5000/About and inspect the headers to view the result:

::: moniker range=">= aspnetcore-2.1"

Add a handler model convention to all pages

Use Conventions to create and add an IPageHandlerModelConvention to the collection of IPageConvention instances that are applied during page handler model construction.

public class GlobalPageHandlerModelConvention
    : IPageHandlerModelConvention
{
    public void Apply(PageHandlerModel model)
    {
        ...
    }
}

Startup.ConfigureServices:

services.AddMvc()
    .AddRazorPagesOptions(options =>
        {
            options.Conventions.Add(new GlobalPageHandlerModelConvention());
        });

::: moniker-end

Page route action conventions

The default route model provider that derives from IPageRouteModelProvider invokes conventions which are designed to provide extensibility points for configuring page routes.

Folder route model convention

Use AddFolderRouteModelConvention to create and add an IPageRouteModelConvention that invokes an action on the PageRouteModel for all of the pages under the specified folder.

The sample app uses AddFolderRouteModelConvention to add an {otherPagesTemplate?} route template to the pages in the OtherPages folder:

[!code-csharp]

The xref:Microsoft.AspNetCore.Mvc.ApplicationModels.AttributeRouteModel.Order* property for the xref:Microsoft.AspNetCore.Mvc.ApplicationModels.AttributeRouteModel is set to 2. This ensures that the template for {globalTemplate?} (set earlier in the topic to 1) is given priority for the first route data value position when a single route value is provided. If a page in the Pages/OtherPages folder is requested with a route parameter value (for example, /OtherPages/Page1/RouteDataValue), "RouteDataValue" is loaded into RouteData.Values["globalTemplate"] (Order = 1) and not RouteData.Values["otherPagesTemplate"] (Order = 2) due to setting the Order property.

Wherever possible, don't set the Order, which results in Order = 0. Rely on routing to select the correct route.

Request the sample's Page1 page at localhost:5000/OtherPages/Page1/GlobalRouteValue/OtherPagesRouteValue and inspect the result:

Page route model convention

Use AddPageRouteModelConvention to create and add an IPageRouteModelConvention that invokes an action on the PageRouteModel for the page with the specified name.

The sample app uses AddPageRouteModelConvention to add an {aboutTemplate?} route template to the About page:

[!code-csharp]

The xref:Microsoft.AspNetCore.Mvc.ApplicationModels.AttributeRouteModel.Order* property for the xref:Microsoft.AspNetCore.Mvc.ApplicationModels.AttributeRouteModel is set to 2. This ensures that the template for {globalTemplate?} (set earlier in the topic to 1) is given priority for the first route data value position when a single route value is provided. If the About page is requested with a route parameter value at /About/RouteDataValue, "RouteDataValue" is loaded into RouteData.Values["globalTemplate"] (Order = 1) and not RouteData.Values["aboutTemplate"] (Order = 2) due to setting the Order property.

Wherever possible, don't set the Order, which results in Order = 0. Rely on routing to select the correct route.

Request the sample's About page at localhost:5000/About/GlobalRouteValue/AboutRouteValue and inspect the result:

::: moniker range=">= aspnetcore-2.2"

Use a parameter transformer to customize page routes

Page routes generated by ASP.NET Core can be customized using a parameter transformer. A parameter transformer implements IOutboundParameterTransformer and transforms the value of parameters. For example, a custom SlugifyParameterTransformer parameter transformer changes the SubscriptionManagement route value to subscription-management.

The PageRouteTransformerConvention page route model convention applies a parameter transformer to the folder and file name segments of automatically generated page routes in an app. For example, the Razor Pages file at /Pages/SubscriptionManagement/ViewAll.cshtml would have its route rewritten from /SubscriptionManagement/ViewAll to /subscription-management/view-all.

PageRouteTransformerConvention only transforms the automatically generated segments of a page route that come from the Razor Pages folder and file name. It doesn't transform route segments added with the @page directive. The convention also doesn't transform routes added by xref:Microsoft.Extensions.DependencyInjection.PageConventionCollectionExtensions.AddPageRoute*.

The PageRouteTransformerConvention is registered as an option in Startup.ConfigureServices:

public void ConfigureServices(IServiceCollection services)
{
    services.AddMvc()
        .AddRazorPagesOptions(options =>
            {
                options.Conventions.Add(
                    new PageRouteTransformerConvention(
                        new SlugifyParameterTransformer()));
            });
}

public class SlugifyParameterTransformer : IOutboundParameterTransformer
{
    public string TransformOutbound(object value)
    {
        if (value == null) { return null; }

        // Slugify value
        return Regex.Replace(value.ToString(), "([a-z])([A-Z])", "$1-$2").ToLower();
    }
}

::: moniker-end

Configure a page route

Use AddPageRoute to configure a route to a page at the specified page path. Generated links to the page use your specified route. AddPageRoute uses AddPageRouteModelConvention to establish the route.

The sample app creates a route to /TheContactPage for Contact.cshtml:

[!code-csharp]

The Contact page can also be reached at /Contact via its default route.

The sample app's custom route to the Contact page allows for an optional text route segment ({text?}). The page also includes this optional segment in its @page directive in case the visitor accesses the page at its /Contact route:

[!code-cshtml]

Note that the URL generated for the Contact link in the rendered page reflects the updated route:

Visit the Contact page at either its ordinary route, /Contact, or the custom route, /TheContactPage. If you supply an additional text route segment, the page shows the HTML-encoded segment that you provide:

Page model action conventions

The default page model provider that implements IPageApplicationModelProvider invokes conventions which are designed to provide extensibility points for configuring page models. These conventions are useful when building and modifying page discovery and processing scenarios.

For the examples in this section, the sample app uses an AddHeaderAttribute class, which is a ResultFilterAttribute, that applies a response header:

[!code-csharp]

Using conventions, the sample demonstrates how to apply the attribute to all of the pages in a folder and to a single page.

Folder app model convention

Use AddFolderApplicationModelConvention to create and add an IPageApplicationModelConvention that invokes an action on PageApplicationModel instances for all pages under the specified folder.

The sample demonstrates the use of AddFolderApplicationModelConvention by adding a header, OtherPagesHeader, to the pages inside the OtherPages folder of the app:

[!code-csharp]

Request the sample's Page1 page at localhost:5000/OtherPages/Page1 and inspect the headers to view the result:

Page app model convention

Use AddPageApplicationModelConvention to create and add an IPageApplicationModelConvention that invokes an action on the PageApplicationModel for the page with the specified name.

The sample demonstrates the use of AddPageApplicationModelConvention by adding a header, AboutHeader, to the About page:

[!code-csharp]

Request the sample's About page at localhost:5000/About and inspect the headers to view the result:

Configure a filter

ConfigureFilter configures the specified filter to apply. You can implement a filter class, but the sample app shows how to implement a filter in a lambda expression, which is implemented behind-the-scenes as a factory that returns a filter:

[!code-csharp]

The page app model is used to check the relative path for segments that lead to the Page2 page in the OtherPages folder. If the condition passes, a header is added. If not, the EmptyFilter is applied.

EmptyFilter is an Action filter. Since Action filters are ignored by Razor Pages, the EmptyFilter no-ops as intended if the path doesn't contain OtherPages/Page2.

Request the sample's Page2 page at localhost:5000/OtherPages/Page2 and inspect the headers to view the result:

Configure a filter factory

ConfigureFilter configures the specified factory to apply filters to all Razor Pages.

The sample app provides an example of using a filter factory by adding a header, FilterFactoryHeader, with two values to the app's pages:

[!code-csharp]

AddHeaderWithFactory.cs:

[!code-csharp]

Request the sample's About page at localhost:5000/About and inspect the headers to view the result:

Replace the default page app model provider

Razor Pages uses the IPageApplicationModelProvider interface to create a DefaultPageApplicationModelProvider. You can inherit from the default model provider to provide your own implementation logic for handler discovery and processing. The default implementation (reference source) establishes conventions for unnamed and named handler naming, which is described below.

Default unnamed handler methods

Handler methods for HTTP verbs ("unnamed" handler methods) follow a convention: On<HTTP verb>[Async] (appending Async is optional but recommended for async methods).

Unnamed handler method	Operation
`OnGet`/`OnGetAsync`	Initialize the page state.
`OnPost`/`OnPostAsync`	Handle POST requests.
`OnDelete`/`OnDeleteAsync`	Handle DELETE requests†.
`OnPut`/`OnPutAsync`	Handle PUT requests†.
`OnPatch`/`OnPatchAsync`	Handle PATCH requests†.

†Used for making API calls to the page.

Default named handler methods

Handler methods provided by the developer ("named" handler methods) follow a similar convention. The handler name appears after the HTTP verb or between the HTTP verb and Async: On<HTTP verb><handler name>[Async] (appending Async is optional but recommended for async methods). For example, methods that process messages might take the naming shown in the table below.

Example named handler method	Example operation
`OnGetMessage`/`OnGetMessageAsync`	Obtain a message.
`OnPostMessage`/`OnPostMessageAsync`	POST a message.
`OnDeleteMessage`/`OnDeleteMessageAsync`	DELETE a message†.
`OnPutMessage`/`OnPutMessageAsync`	PUT a message†.
`OnPatchMessage`/`OnPatchMessageAsync`	PATCH a message†.

†Used for making API calls to the page.

Customize handler method names

Assume that you prefer to change the way unnamed and named handler methods are named. An alternative naming scheme is to avoid starting the method names with "On" and use the first word segment to determine the HTTP verb. You can make other changes, such as converting the verbs for DELETE, PUT, and PATCH to POST. Such a scheme provides the method names shown in the following table.

Handler method	Operation
`Get`	Initialize the page state.
`Post`/`PostAsync`	Handle POST requests.
`Delete`/`DeleteAsync`	Handle DELETE requests†.
`Put`/`PutAsync`	Handle PUT requests†.
`Patch`/`PatchAsync`	Handle PATCH requests†.
`GetMessage`	Obtain a message.
`PostMessage`/`PostMessageAsync`	POST a message.
`DeleteMessage`/`DeleteMessageAsync`	POST a message to delete.
`PutMessage`/`PutMessageAsync`	POST a message to put.
`PatchMessage`/`PatchMessageAsync`	POST a message to patch.

†Used for making API calls to the page.

To establish this scheme, inherit from the DefaultPageApplicationModelProvider class and override the CreateHandlerModel method to supply custom logic for resolving PageModel handler names. The sample app shows you how this is done in its CustomPageApplicationModelProvider class:

[!code-csharp]

Highlights of the class include:

The class inherits from DefaultPageApplicationModelProvider.
The TryParseHandlerMethod processes a handler to determine the HTTP verb (httpMethod) and named handler name (handlerName) when creating the PageHandlerModel.
- An Async postfix is ignored, if present.
- Casing is used to parse the HTTP verb from the method name.
- When the method name (without Async) is equal to the HTTP verb name, there's no named handler. The handlerName is set to null, and the method name is Get, Post, Delete, Put, or Patch.
- When the method name (without Async) is longer than the HTTP verb name, there's a named handler. The handlerName is set to <method name (less 'Async', if present)>. For example, both "GetMessage" and "GetMessageAsync" yield a handler name of "GetMessage".
- DELETE, PUT, and PATCH HTTP verbs are converted to POST.

[!code-csharp]

The page model in Index.cshtml.cs shows how the ordinary handler method naming conventions are changed for pages in the app. The ordinary "On" prefix naming used with Razor Pages is removed. The method that initializes the page state is now named Get. You can see this convention used throughout the app if you open any page model for any of the pages.

Each of the other methods start with the HTTP verb that describes its processing. The two methods that start with Delete would normally be treated as DELETE HTTP verbs, but the logic in TryParseHandlerMethod explicitly sets the verb to POST for both handlers.

Note that Async is optional between DeleteAllMessages and DeleteMessageAsync. They're both asynchronous methods, but you can choose to use the Async postfix or not; we recommend that you do. DeleteAllMessages is used here for demonstration purposes, but we recommend that you name such a method DeleteAllMessagesAsync. It doesn't affect the processing of the sample's implementation, but using the Async postfix calls out the fact that it's an asynchronous method.

[!code-csharp]

Note the handler names provided in Index.cshtml match the DeleteAllMessages and DeleteMessageAsync handler methods:

[!code-cshtml]

Async in the handler method name DeleteMessageAsync is factored out by the TryParseHandlerMethod for handler matching of POST request to method. The asp-page-handler name of DeleteMessage is matched to the handler method DeleteMessageAsync.

MVC Filters and the Page filter (IPageFilter)

MVC Action filters are ignored by Razor Pages, since Razor Pages use handler methods. Other types of MVC filters are available for you to use: Authorization, Exception, Resource, and Result. For more information, see the Filters topic.

The Page filter (IPageFilter) is a filter that applies to Razor Pages. For more information, see Filter methods for Razor Pages.

Additional resources

Razor Pages authorization conventions

32 KiB Raw Blame History

Razor Pages route and app conventions in ASP.NET Core

Route order

Model conventions

Add a route model convention to all pages

Add an app model convention to all pages

Add a handler model convention to all pages

Page route action conventions

Folder route model convention

Page route model convention

Use a parameter transformer to customize page routes

Configure a page route

Page model action conventions

Replace the default page app model provider

MVC Filters and the Page filter (IPageFilter)

Additional resources

32 KiB

Raw Blame History