Extension:Semantic Forms/Linking to forms

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How do you get users to forms? The standard way is via the #forminput parser function call, which displays a single input for users to enter the name of a page; if they enter such a name and click the button, they are sent to a form to create that page - unless a page with that name already exists, in which case they are sent to a form for editing the existing page. This is what is known as the "two-step process". The reason for the initial step, of having the user first enter the page name, is to ensure that users don't accidentally overwrite existing pages. This process is so standard that it is built into the default forms produced by Semantic Forms' "Special:CreateForm" and "Special:CreateClass" helper pages: any form-definition page created by Semantic Forms includes, at the top, a call to #forminput, so that users who go to that form page can automatically start to use the form.

However, it's also possible to have users skip the first step, of entering the page name - that's what you should do if the form contains a formula for setting the page title based on the user input. That's the "one-step process", and it uses the parser function #formlink instead of #forminput.

Query forms, that use Special:RunQuery, have their own linking method, using the parser function #queryformlink.

The two-step process[edit]

The two-step process, i.e. the standard way to get users to forms, is done using the #forminput parser function.

Using #forminput[edit]

Here is the syntax of the #forminput parser function:

{{#forminput:form=|size=|default value=|button text=|query string=query string parameters|autocomplete on category=|autocomplete on namespace=|placeholder=|popup}}

All arguments are optional. An explanation of the parameters:

  • form= - the name of the SF form to be used; if it is left empty, a dropdown will appear, letting the user choose among all existing forms.
  • size= - the size of the text input (default is 25).
  • default value= - the starting value of the input (default is blank).
  • button text= - the text that will appear on the "submit" button (default is "Create or edit page").
  • query string= - you can use this option to pass information to the form; this information generally takes the form of templateName[fieldName]=value. It should look like a typical URL query string; an example would be "query string=namespace=User&User[Is_employee]=yes".
    • additionally, any query string values can be passed directly in as parameters - so the values above could instead be passed in as "|namespace=User|User[Is_employee]=yes".
  • autocomplete on category= - adds autocompletion to the input, using the names of all pages in a specific category.
  • autocomplete on namespace= - adds autocompletion to the input, using the names of all pages in a specific namespace (only one of these two can be used).
  • placeholder= - "placeholder" text that appears in the form input before the user types anything.
  • popup - opens the form in a popup window.
  • no autofocus - by default; the form input gets autofocus, i.e., the cursor is placed in the input when the page loads; this parameter specifies not to do this.

Adding pages of a specific namespace[edit]

You can have a page-input form create pages within a specific namespace (like 'User:') by default, without forcing users to type in that namespace every time. To do that, add 'namespace=namespace-name' to the "query string=" parameter.

(Note that, if you want to use SMW on a custom namespace, you need to add the namespace to $smwgNamespacesWithSemanticLinks.)

Adding sub-pages[edit]

In MediaWiki, you can create subpages by including a slash in the page name. To have the page that's added automatically be a subpage, you can add a value for "super_page=" in the query string. To make it a subpage of the current page, you can set this value to "super_page={{PAGENAME}}". This will prepend a "current-page-name/" at the beginning of the page name that the user types in.

The one-step process[edit]

You can have the name of the page created by the form be set automatically, by adding a "page name" parameter within the form definition's "info" tag. There are two types of "variables" one can include in the value for this parameter:

  • <template-name[field-name]> - gets replaced with the value for the specified field field-name in the specified template template-name.
  • <unique number> - by default, gets replaced by the lowest number for which the page title that's generated is unique. Normally, this value starts out as blank, then goes to 2, then 3, etc. However, one can manually set the starting number for this value, by adding a " start= " parameter; this number must be 0 or higher. For instance, to have the number start at 1 and go upward, you should set the tag to be "<unique number;start=1>". You can also instead set it to be a random six-digit number, by adding the "random" parameter, so that the tag looks like "<unique number;random>". You can also set the number of digits to be something other than 6, by adding a number after "random", like "<unique number;random;4>". Note that the parameters in all these cases are delimited by semicolons.
    • Note that the "page name=" value cannot start with "<unique number>", due to a bug in Semantic Forms; there has to be some text before that. And it cannot contain the character "#", because MediaWiki does not allow pound signs in page titles.

As an example, imagine a form for storing notable quotes. Its {{{info}}} tag could have a parameter of "page name=<Quote[Author name]> quote <unique number;start=1>". This would include the author's name in the name of every quote page, as well as a number to guarantee the uniqueness of every opinion-item page added. A user could then go to the URL "http://mywiki.com/Special:FormEdit/Quote" and fill out the form; if they set the author to be "Ernest Hemingway", and no other quotes in the wiki had him as an author, then hitting the "Save page" button would result in a new page called "Ernest Hemingway quote 1" .

The "start" value can have leading zeroes; a value of "001", for instance, would lead to pages that had the value "001", then "002", etc.

The "page name=" value gets parsed by the MediaWiki parser, so you can also add parser functions, pre-defined variables, etc. into the value.

Note that users must be sent to the page "Special:FormEdit/form-name" for this automatic page-setting to work; if they somehow end up at a #forminput call and are prompted for a page name, that name will override whatever the automatic page name would be.

Using #formlink[edit]

If you want, you can generate this link using the #formlink parser function, instead of creating the URL directly. This function is called as:

{{#formlink:form=|link text=|link type=|query string=query string parameters|target=|tooltip=|popup|new window}}

An explanation of the parameters:

  • The form=, query string and popup arguments work much the same way that their equivalents in #forminput work.
  • link text= - works like button text= (see above).
  • link type= - sets the display of the link:
    • if it's set to button, the link will show up as a button;
    • if it's set to post button, it will be a button that sends the query-string value(s) using "POST" instead of via the URL — this is helpful when a lot of data has to be preloaded, and it is more robust with special characters like line breaks in the query string;
    • if it's set to blank or anything else, it will show up as a regular link.
  • target= - shouldn't usually be used, but it sets the "target" page to be edited, if you want to link to the editing of a specific page.
  • tooltip= - displays a tooltip, displayed if a user hovers the link.
  • popup - opens the form in a popup window. (Note: popup forms may not work if you have the ConfirmEdit extension installed - users might not see the CAPTCHA they need to fill out.)
  • new window - opens the form in a new window or tab, depending on the browser.

An example call to #formlink would be:

{{#formlink:form=Quote|link text=Add a quote for this author|link type=button|query string=Quote[Author]={{PAGENAME}} }}

This will link from the page, via a button, to a form for adding a quote, with the "Author" field filled in with the current page name.

Note that if any part of your query string — such as a page name or anything else — contains characters such as apostrophes ('), ampersands (&), or plus signs (+), you will need to URL-encode that value. For that, you can use the urlencode function from the ParserFunctions extension. The example above, for instance, would need to change to: Quote[Author]={{urlencode:{{PAGENAME}}}}.}}

You may want to have the link to the form be an image, instead of text or a button. For that, you could call something like:

{{#formlink:form=Quote|link text=[[File:edit.png|link=]]}}

Redirecting to another page post-save[edit]

You can have the form redirect to another page after it finishes saving, by adding "returnto=page name" among the query string parameters in either #forminput or #formlink.

Linking to query forms[edit]

You can link to query forms, i.e. forms run within the page Special:RunQuery, by using the #queryformlink parser function. This is called in the same way as #formlink, except that there's no "target" parameter. For a more complete explanation, see Creating links to query forms.

Pointing red links to a form[edit]

In MediaWiki, links to nonexistent pages are called 'red links', because they are usually colored red. By default, these links go to a page for adding the article to the wiki using the standard edit interface. However, you can instead set red links to link directly to a form to create that page, if the correct form is known in advance; and you can additionally have all other red links point to a helper page that lets the user choose which of the wiki's forms to use (if any).

Using #formredlink[edit]

To have a specific link (either on its own, or within a template) point to a form if the page it is pointing to does not exist, use the #formredlink parser function. A typical call to #formredlink will go inside a template, and will look like:


The overall syntax of #formredlink is:

{{#formredlink:form=|link text=|existing page link text=|link type=|query string=query string parameters|target=|tooltip=|popup|new window|create page}}

These parameters are very similar to those of #formlink (see above). It has two additional parameters:

  • "existing page link text=" - sets the text of the link when the target page being pointed to exists already (the "link text=" parameter takes effect only when the target does not exist).
  • "create page" - causes red-linked pages to get automatically created by the system. It should be noted that it may take a while for each page to be created, since page creation is done through MediaWiki "jobs", which can take anywhere from a few seconds to several hours or more to run, depending on the length of the job queue. Pages created with this method will be associated with user ID 1 (the first user created on the wiki), unless you set $sfgAutoCreateUser to another username.

There may be times when you are not sure which form a linked-to page will use; it could be one of a number of choices. You can set it so that the user gets other possibilities when they click on the red link, by adding one or more "alt_form" query string parameters to the #formredlink call, each with its own number.

As an example, see this page. Both the author and the source are red-linked, but the links take you to forms for adding these two pages (please do not actually fill out and submit these forms, because that would ruin the example). When you get to the forms for each page, you can see, at the top, that there are alternative forms that you can select for adding each page. That is enabled by the following two calls to #formredlink in the template where those links are defined:

For the source:

 {{#formredlink:target={{{source|}}}|alt_form[0]=Source|alt_form[1]=Magazine|alt_form[2]=Online magazine}}

For the author:

 {{#arraymap:{{{author|}}}|,|x|{{#set:Was written by=x}}{{#formredlink:target=x|form=Author|alt_form[0]=Editorial board}}}}

In the example page, the "source" call creates a link to Special:FormEdit/The_Denver_Post?alt_form[0]=Source&alt_form[1]=Magazine&alt_form[2]=Online magazine&redlink=1. Note that no main/default form is specified; only alternate forms.

The "author" call is more complex because that field can hold a list of values. #arraymap is used to put in a call to #formredlink for each individual value; as well as to store each individual value using an SMW property.

Form-associated namespaces[edit]

If you've defined a namespace as having a default form, red-links that go to a page within that namespace will also go to the right 'add data' form, without any extra work needed.

Pointing red links to a "form chooser"[edit]

For red links not defined by #formredlink and not pointing to a form-associated namespace, you can have every such link point to a helper page, that lets the user choose which of the wiki's forms to use to create this page - or to use no form at all. You can enable this functionality simply by adding the following to LocalSettings.php, below the inclusion of SF:

$sfgLinkAllRedLinksToForms = true;

You can see an example of this interface by clicking on the red link here (please do not create this page).

Preloading data[edit]

You may want a form to already contain some data when the user goes to it. (Note that this only applies to adding new data, or to query forms; for editing an existing page, there is no way to set the contents of the form to anything other than the current contents of that page.) There are various ways to do this:

  • Specify a "default" value for whatever fields you want to have a value for in the form.
  • Specify a "preload" page for the "free text" input, which will preload the free text field with the contents of that page.
  • Add 'preload=preload-page-name' to the query string value in the 'forminput' call; this will preload the entire form with the contents of that page.
  • Similarly, you can add a "preload=..." value to the query string for a 'FormStart' or 'FormEdit' URL.
  • Add "template-name[field-name]=field-value" to the query string value in the 'forminput' call, to set the value for a specific field. To preload values for more than one field use "&": "template-name[field-name-1]=field-value-1&template-name[field-name-2]=field-value-2"
  • To preload values for multiple-instance templates, add the instance number after the template name. So you could have something like "template-name[1][field-name]=field-value&template-name[2][field-name]=field-value" for two instances.
  • Similarly, you can add a value for a specific field to the URL query string for 'FormStart' or 'FormEdit'.
  • Finally, you can create your own custom handling, using the 'sfEditFormPreloadText' hook. If another extension calls this hook, it can preload data however it wants. The function registered with this hook should have a header like "function-name(&$page_contents, $page_title, $form_title)".

Modifying pages automatically[edit]

You can create links that, when clicked on, create or edit pages automatically in the background, with a preloaded set of values, using the #autoedit parser function. This function is called, and is displayed, in a very similar manner to #formlink - the difference is that the link only performs an action in the background, instead of bringing the user to a form. The syntax for #autoedit is:

{{#autoedit:form=|target=|link text=|link type=|summary=|tooltip=|query string=query string parameters|reload}}

All these parameters work in the same way as they do in #formlink, with two exceptions:

  • "reload" is a new parameter that, if added to the call, reloads the current page after the link is clicked.
  • Like with #formlink, "link type" sets the type of display and can be set to "link", "button" and "post button". However, for #formlink, a missing value for "link type" is the same as setting the value to "link"; while for #autoedit, the two are different. In #autoedit, a missing value for "link type" will display the text as text, without a link, while setting "link type=link" will display it as a link.

As an example, let's say you want to create a simple voting scheme, letting users vote between "Vanilla", "Chocolate" and "Strawberry". You have a page for each, and each one contains a template called "Flavor", with a field called "Num votes" - that field, in turn, sets a semantic property called "Has number of votes". And there is also a form, also called "Flavor", to edit such pages. To create a link that, when clicked, increments the number of votes in the "Vanilla" page by one, you could place the following call on the page:

{{#autoedit:form=Flavor|target=Vanilla|link text=Vote for Vanilla|link type=link|query string=Flavor[Num votes]={{#expr:{{#show:Vanilla|?Has number of votes}} + 1}}|summary=Adding vote {{#expr:{{#show:Vanilla|?Has number of votes}} + 1}}. }}

This functionality is also available via the MediaWiki API, as the sfautoedit action - this enables outside scripts, and bots, to easily modify template calls within wiki pages. You can find the full documentation on this by searching for "sfautoedit" here.