Editing API:EPrints/Plugin/Screen (section)

==METHODS==
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===properties_from===

<source lang="perl">$screen->properties_from()

</source>
Called by the [[API:EPrints/ScreenProcessor|EPrints::ScreenProcessor]] very early in the response process.

This method should be used to set up the response by, for example getting CGI query parameters and storing them in the processor object.

Because this method is called '''before''' [[API:EPrints/Plugin/Screen#can_be_viewed|can_be_viewed]] no changes to the system should be made here.

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===redirect_to_me_url===

<source lang="perl">$url = $screen->redirect_to_me_url()

</source>
If the request is a POST the screen is given an opportunity to redirect the user, avoiding double-POSTs if the user reloads the resulting page.

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===render===

<source lang="perl">$xhtml = $screen->render()

</source>
Render the page body.

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===render_links===

<source lang="perl">$xhtml = $screen->render_links()

</source>
Render any elements for the page &lt;head&gt; section.

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===hidden_bits===

<source lang="perl">@params = $screen->hidden_bits()

</source>
Returns a key-value list of values that must be set when referring to this screen.

At the top-level this is just the 'screen' id.

Historically render_hidden_bits() - which built up a set of hidden inputs in XHTML - was used but this had the downside of not being usable with GET requests. Screen plugins now have a mix of approaches, so care is needed when sub-classing <code>hidden_bits</code>.

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===wishes_to_export===

<source lang="perl">$bool = $screen->wishes_to_export()

</source>
If true, instead of calling the render* methods the export* methods will be used.

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===export===

<source lang="perl">$screen->export()

</source>
Called when [[API:EPrints/Plugin/Screen#wishes_to_export|wishes_to_export]] is true.

This method should generate an HTTP response directly (e.g. by printing to STDOUT).

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===export_mimetype===

<source lang="perl">$mime_type = $screen->export_mimetype()

</source>
Return the MIME type of the HTTP response (as will be generated by [[API:EPrints/Plugin/Screen#export|export]]).

Default is to use "text/plain".

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===render_form===

<source lang="perl">$xhtml = $screen->render_form( [ METHOD [, ACTION ] ] )

</source>
Render an XHTML form that will call this screen. If the METHOD is POST will apply cross-site request forgery protection.

Unless you have a good reason not to you should always use render_form() to add forms to your HTTP response, which ensures the correct context and request protections are in place.

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===verify_csrf===

<source lang="perl">$ok = $screen->verify_csrf()

</source>
Verify that the CSRF token in the user agent's cookie matches the token passed in the form value.

If the CSRF check fails no action should be taken as this may be an attempt to forge a request.

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===render_title===

<source lang="perl">$xhtml = $screen->render_title

</source>
Render the page title.

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===list_items===

<source lang="perl">@screen_opts = $screen->list_items( $list_id, %opts )

</source>
Returns a list of screens that appear in list $list_id ordered by their position.

Each screen opt is a hash ref of:

<pre>  screen - screen plugin
  screen_id - screen id
  position - position (positive integer)
  action - the action, if this plugin is for an action list</pre>

Incoming opts:

<pre>  filter =&gt; 1 or 0 (default 1)
  params =&gt; {}</pre>

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===has_action===

<source lang="perl">$ok = $screen->has_action( $action_id )

</source>
Returns true if this screen has an action $action_id.

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===action_icon_url===

<source lang="perl">$url = $screen->action_icon_url( $action )

</source>
Returns the relative URL to the $action icon for this screen.

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===render_action_link===

<source lang="perl">$frag = $screen->render_action_link()

</source>
Returns a link to this screen.

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