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== withForm



=== Purpose


Used to handle duplicate form submissions.


=== Examples


[source,groovy]
----
withForm {
   // good request
}.invalidToken {
   // bad request
}
----


=== Description


The `withForm` method requires the use of the `useToken` attribute in a link:{gspTagsRefFromRef}form.html[form]

[source,xml]
----
<g:form useToken="true" ...>
----

Then in your controller code you can use the `withForm` method to handle valid and invalid requests:

[source,groovy]
----
withForm {
   // good request
}.invalidToken {
   // bad request
}
----

Tokens are single-use. A valid token is consumed atomically when `withForm` validates it, so duplicate concurrent submissions for the same token allow exactly one request to run the valid block. Grails stores token state in the session with a limit of 100 form URL buckets and 100 tokens per URL; after those limits, the oldest bucket or oldest token is discarded and later submission of that form is handled as `invalidToken`.

See link:{guidePath}theWebLayer.html#formtokens[Handling Duplicate Form Submissions] for more information.
