The Form Tag Helper

The form tag helper generates a URL based on the application's routing configuration and applies it to the form's action attribute. It also generates a hidden field within the form containing the value of an anti-forgery token for request verification. If a method attribute is not specified in the form element, the form tag helper will render one with a value of post by default.

Attribute	Description
action	The name of the action method on an MVC controller
all-route-data1	Multiple route parameter values
antiforgery7	Specifies whether an anti-forgery token is rendered.
area	The name of the MVC area
controller	The name of the MVC controller
fragment2	The fragment in the URL
host	The domain
page3	The Razor page to link to
page-handler4	The Razor page handler method to invoke
protocol	The protocol (http, https, ftp etc)
route5	The name of the route
route-6	A single route parameter value

Notes

1. If the target URL for the action includes multiple route parameters, their values can be packaged as a Dictionary<string, string> and passed to the all-route-data parameter:

   @{   
       var d = new Dictionary<string, string>
           {
              { "key1", "value1" },
              { "key2", "value2" }
           };
   }
   
   <form asp-all-route-data="d">...</form>
   

   If the route has parameters defined, the form tag helper will output the values as URL segments: <form action="/Page/value1/value2">...</form>. If it doesn't, the route parameters will be appended to the URL as query string values: <form action="/Page?key1=value1&amp;key2=value2" method="post">...</form>.

2. The fragment is the value after a hash or pound sign (#) in a URL used to identify a named portion of a document. The "Notes" heading above has an identity value of "notes" and can be referenced in a URL using the anchor tag helper like this:

   <form asp-fragment="notes">...</form>
   

   producing this HTML: <form action="/Page#notes" method="post">...</form>. It should be noted that fragments have no influence on the submission of a form.

3. The name of the Razor page to link to must be provided without the file extension:

   <form asp-page="page">...</form>
   

   If no page name is specified, the tag helper will generate a link to the current page.

4. The page handler method name will appear as a query string value unless it has been included as a route parameter for the target page.

5. Razor pages doesn't support named routes. This parameter will only be used for MVC routes.

6. The route- parameter enables you to specify the value for a single route value. The route parameter name is added after the hyphen. Here, the route parameter name is "key1":
   <form asp-route-key1="value1">...</form>
   This renders as
   <form action=/Page/value1" method="post">...</form>
   if the key1 parameter is defined as part of the page's route template, or
   <form action="/Page?key1=value1" method="post">...</form>
   if not.

7. The anti-forgery token is rendered as a hidden input named __RequestVerificationToken. It will be rendered by default, unless the form has an action attribute specified, the form's method is set to GET or the antiforgerytoken value is set to false. If you disable the generation of the anti-forgery token, you must also disable request verification on the PageModel class that houses the processing page handler.