YK: Chapter 3: Editing in MediaWiki
In MediaWiki, nearly all page-specific actions are accessible through what are usually tabs, though it depends on the skin: in some cases the “tabs” are just links displayed on the side, and in the case of Vector, the default skin, some of the tab actions are dropdown links, viewable alongside the main tabs. The exact set of tabs/dropdown actions/etc. one sees depends on the type of page it is, the permissions one has, and the extensions installed. Figure 3.1 shows the (nearly) standard view of tabs and dropdown actions that an administrator would see, for a regular page in MediaWiki, with the Vector skin (along with the search interface alongside it).
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Figure 3.1 Row of tabs in the Vector skin
The “Edit” tab shows up as “View source” instead, if the user isn’t allowed to edit the page, in Vector and most other skins.
We’ll cover most of these actions in this chapter. The one feature that makes this different from the standard view an administrator would have is the “Refresh” action, which is defined by the Semantic MediaWiki extension you can read about that here.
Creating and editing pages
In MediaWiki, every page’s URL is also its title; there are no URLs that simply look like “?id=123456”, of the type that appear in many other content-management systems. That’s important, because it means that the creation and renaming of pages can be done in a transparent way, open to all users.
The way to create a new page, and edit an existing page, are basically the same: in both cases, you first have to go to that page. How do you get to a page? Interestingly, for both existing pages and pages that don’t exist yet, there are the same three ways to do it:
Type in the page name in the URL
Search on that page name, and then either arrive at the page (for existing pages), or follow the link to create it in the search results (for pages that don’t exist)
Follow a link to that page.
A link to a nonexistent page is usually called a “red link”. By default, they’re red, which easily distinguishes them from links to pages that exist, which are usually blue. The actual MediaWiki term for them, for what it’s worth, is “broken link” (though “redlink” is also used, in URLs). Broken/red links are useful for indicating that a page that doesn’t exist yet should be created. With Semantic Forms (an extension we’ll get to later), you can actually have red-linked pages created automatically in certain cases but most of the time, this has to be done manually.
Page names
For the most part, page names can contain any Unicode character. The following characters, however, are not allowed in page names:
- < > [ ] | { }
The underscore character, _, could be added to that list as well, since underscores are simply treated the same as spaces.
By default, page names always start with an uppercase letter: if a page name gets typed in that starts with a lowercase letter, it will simply get capitalized by the system. This can be changed, however, by adding the following to LocalSettings.php:
$wgCapitalLinks = false;
Page names are restricted to 255 bytes, which, depending on the character set being used, can be as many as 255 characters or as few as 63 characters. Standard Latin characters are one byte each, while most other languages’ characters are represented using two or three bytes, and some archaic languages, mathematical symbols, etc. take four bytes.
Editing mode
Once you’re at a page, you will see a slightly different interface depending on whether you’re allowed to edit it. If you can’t edit the page, there will most likely be a tab named “View source”, that lets you view the source wikitext of the page (if you’re interested in doing that). If you can edit the page, on the other hand, that same tab will most likely be called “Edit” instead. In that case, to edit the page, you just have to click on the “Edit” tab, and start typing. For new pages, the tab is called “Create” instead of “Edit”, and there’s usually an explanatory message on the page that includes a link to that tab, but otherwise it’s the same. In both cases, you end up at a URL that ends with “action=edit”, which indicates that you’re now in editing mode.
For existing pages, you can most likely also click “Edit” on any page section usually, every section header will have a link that looks like “[Edit]” near it. This is quite useful if you have a small change you want to make, it’s always better to only edit the section in which it appears, because there’s less text to deal with.
The edit page consists of, essentially, one big text area, plus some helper inputs at the bottom, including, most notably, the “Save page” button. The text of the page, or section, being edited goes in the big text area; it’s meant to be written in a syntax called wikitext, which is simpler than HTML but which can also include a lot of scripting-like functionality; this is covered in all of Chapter 4 . There are various toolbars and utilities that can be used with editing. By default, the top of the text area has a toolbar that looks like Figure 3.2.
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Figure 3.2 Standard MediaWiki editing toolbar
You can also use an extension called WikiEditor (we’ll cover extensions later), which provides a nicer toolbar, with support for special characters (symbols, and non-Latin characters), and other features. Figure 3.3 shows what it looks like, with the “Advanced” option selected.
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Figure 3.3 WikiEditor extension editing toolbar
You can read more about it here:
https://www.mediawiki.org/wiki/Extension:WikiEditor
There are some extensions that support intuitive, WYSIWYG-style editing, although they all have flaws at the moment; see here for more discussion of these (and a full explanation of “WYSIWYG”).
There’s also the Semantic Forms extension, which lets you provide a form for editing, in addition to or instead of the standard edit page; this extension is covered in depth in Chapter 17.
Here is what the bottom of the edit page looks like, below the main input for the text:
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In the “Summary” field, the user is supposed to summarize their changes in the current edit; this is very useful when looking at the page history later. Clicking “Watch this page” adds this page to the user’s watchlist (which we’ll get to later in this chapter). “Save page” of course saves the page. “Show preview” shows what the page will look like if it’s saved in its current state, while leaving the edit form underneath the preview, so that the user can keep editing. “Show changes” shows the differences between the current text and the saved page, again with the edit form placed at the bottom. It’s generally a good idea to hit both of these before saving a page, to make sure that everything looks alright, and that nothing was deleted, or added, accidentally.
“Cancel” and “Editing help” are simply links. “Cancel” takes the user back to the regular page, while “Editing help” brings the user to to the page “Help:Editing”, which by default is blank. The latter is a somewhat silly feature it means that every wiki needs to maintain its own editing help page. The best course of action is to simply put in a link on the local page Help:Editing to the following URL:
https://www.mediawiki.org/wiki/Help:Editing
Page history
The next feature available for every content page in MediaWiki is the history page. You can reach it by adding "action=history" to a page’s URL query string, and, as with the edit page, it’s available in most skins via a tab, and in some skins as a sidebar link. In English, the tab is called “History” or "View history", depending on the skin.
The history page doesn’t usually get much attention, although it is, in a sense, the heart of MediaWiki, because being able to see the page history is what lets wikis function like wikis. Because you can always see the entire set of changes, you can open up editing of your content to any group of people, no matter how large, without fear that important data will be lost.
Here are a few rows from the history page for the article “Paul Broca”, on the English-language Wikipedia:
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Every row represents a single edit to the page, and all edits are stored permanently. (In MediaWiki nomenclature, an edit is also known as a “revision”. It’s rarely called a “version”; that word is generally reserved for software.) Each row holds important information and links:
“cur” and “prev” links, and radio buttons, for showing differences (as described in the next section, “Page diffs”)
the date and time in which the edit was made (configured for the current user’s time zone), which link to a page showing that revision
the name of the user who made the edit, or the person’s IP address if the edit wasn’t made by a logged-in user
additional links to the user’s talk page and list of contributions
sometimes, the character “m” (in English), to indicate that the person who made this edit considered it a “minor edit”
the number of bytes in the page in this revision (for Roman letters, the number of bytes is usually equal to the number of characters, although for other languages, like Chinese, there are often three bytes per character)
the user’s own summary of the edit
an “undo” link, for all but the earliest row (covered in the upcoming section, “Undoing”).
Clicking on the date/time brings you to the page for that specific revision each one has its own permanent URL. Going to the URL for a specific edit shows you the contents of the page at that time, in addition to some information at the top about that revision:
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Administrators will also see links for “block” and “rollback” within the rows of the history page. These are both covered in the upcoming section, “Blocking and rollbacks”.
Page diffs
The elements at the beginning of each row “cur” and “prev” links (in English), and the two columns of radio buttons are used to compare between revisions. Clicking on the “prev” link shows you the change made in this revision, while the “cur” link shows the differences between this revision and the current one. The sets of radio buttons, meanwhile, allow for precise comparison of any two revisions the first column is meant to select an older revision, and the second column a newer revision (the JavaScript ensures that you can’t select a row in the second column older than the one in the first column). Clicking on “Compare selected revisions” will display all the differences between the two revisions.
Figure 3.4 shows an example of one such display, from an edit made on November 21, 2011 to the article “Parallel postulate” on the English-language Wikipedia.
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Figure 3.4 A page diff from the English Wikipedia
Colors and bolding are used to show differences. The algorithm used to determine the differences is MediaWiki’s own, and it’s fairly good, though not perfect. When one or more blocks of text are rearranged on the page, for example, the change is often shown as more dramatic than it actually is: it can be displayed as a massive deletion and addition of text, instead of a simple rearrangement.
Undoing
The "undo" link, after the edit summary, allows any user to undo that one change. An "undo" link also appears in any page showing the difference between two revisions. Not every difference can be automatically undone, though, and thus not every "undo" link will work, whether it’s between a large number of revisions or just two adjacent ones. Clicking on an "undo" link that can’t be performed by the system will lead to the error message, "The edit could not be undone due to conflicting intermediate edits."
MediaWiki decides whether or not a change can be undone based on whether the undo would affect any of the edits that have been done since the more recent of the two revisions. The more edits that have been done since the later revision, the smaller the chance that this change can be automatically undone. Conversely, a difference involving the current revision can always be automatically undone, whether it’s back to the previous revision or to any revision before that.
If you can’t undo a change automatically, you’ll have to do it manually, which, for large pages, can be a painful process. In that case, using a text editor can usually make the task easier than editing the text directly within a web page.
Blocking and rollbacks
If you’re an administrator, there are a few more links that you’ll see on every row in the history page. Next to every username or IP address there will also be a "block" link, to block that person (see here ). And, in the top row, near the "undo" link, there will also be a "rollback" link. This is a useful link, which automatically undoes the last edit to the page, as well as any edits made by that same user directly preceding the last one; there’s no need to go through a second screen. It’s especially useful for dealing with vandalism, when you know without a doubt that a certain user’s changes are malicious and should all be undone. It should be used with caution in other circumstances, though: if, for instance, you just want to undo the last change you made to a page, if you hit "rollback" you may be surprised to see that more than one of your edits has been reverted, potentially going all the way back to the first revision of the page. (Though it should be noted that the change done by the rollback is simply recorded as another edit, so the rollback can itself easily be undone.)
Deleting revisions
What if a person puts slanderous text, or reveals secret information, like someone’s phone number, on a wiki page? Of course, you can revert the edit, but that bad text will remain accessible to anyone who views the page history, and, if it’s a public wiki, it could even get linked to from elsewhere. That’s a bad outcome, but thankfully there’s a way for administrators to hide certain revisions altogether. In LocalSettings.php, you can add the following line:
$wgGroupPermissions['sysop']['deleterevision'] = true;
This will give the ’deleterevision’ permission to all administrators. (We’ll get to user groups and user permissions in the next chapter.) You can give this permission to other user groups, although having this exact line is the easiest approach.
If you add this line, any administrator who’s logged in will see another checkbox on each row, and another button above the rows, reading (in English) "Show/hide selected revisions". Selecting any number of checkboxes, and clicking the button, will bring you to a page reading "Delete/undelete revisions". Contrary to its name, this page does not actually delete anything, but rather hides certain revisions (though, as we’ll see later, regular page deletions don’t actually delete any content either). The interface is slightly more complex if more than one revision has been selected. Figure 3.5 shows the interface for one revision, and Figure 3.6 shows it for more than one.
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Figure 3.5 “Show/hide selected revisions” interface for one revision
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Figure 3.6 “Show/hide selected revisions” interface for more than one revision
As you can see, in either case, there are three things that can be hidden: the text of the revision (the most important of the three), the revision summary, and the user who made the revision. Once a revision is hidden, neither administrators nor other users will be able to see the hidden elements of that revision; though they’ll still be able to see that the revision happened. If all three of the above elements are hidden, here’s how that row in the page history will look:
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The most recent revision cannot be hidden; the inclusion of a checkbox on that row appears to just be a mistake in MediaWiki. Once elements of a revision are hidden, that same interface can be used to unhide any of them. Because this feature is so useful, we recommend enabling it for any wiki, public or private.
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Moving pages
Moving a page, in MediaWiki parlance, just means renaming it. The ability to move a page is set by the ’move’ permission, which by default is open to everyone in the ’users’ group, i.e. all logged-in users.
To move a page, click on the tab or dropdown action labeled “Move”. You will then see an interface like this one:
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You can choose to either have a redirect from the old page, or not; it’s recommended to have one, so that links to the old page name will still work. If there are no links, though, then it doesn’t matter.
Moving a page to a title that already exists is effectively the same as deleting the other page; that’s why only people with the ’delete’ permission, usually administrators, are allowed to do it.
If you have a large batch of pages that all need to be renamed in the same way, the Replace Text extension ( see here) may be helpful.
Deleting pages
By default, administrators can delete any page (except for special pages). On a regular page, among the list of tabs, or dropdown actions, an administrator should see one that says “Delete”. Clicking on it will bring you to an interface for deleting the page in question. A page, once deleted, can’t be viewed by anyone; but by default it can be restored by any administrator, with all its revisions intact; so in that sense, no content is ever truly deleted.
Deletion and undeletion ability are governed by the ’delete’ and ’undelete’ permission types, respectively. So, for instance, to allow a user group to only undelete pages, you could add something like this to LocalSettings.php:
$wgGroupPermissions['articlesavers']['undelete'] = true;
Deletions definitely make sense for the case of pages created by spammers or vandals, since such pages are simply noise. And in the case of Wikipedia, deletions make a certain amount of sense because they give a sense of finality to a community decision to get rid of a certain page. (Though such decisions are sometimes overturned.) But for regular pages on regular wikis, where the contents were just considered unnecessary for some reason, blanking a page (i.e., removing its contents and hitting “save”) is often a better strategy.
The advantages of blanking are that anyone can do it, anyone can undo it, and anyone can see what the old contents were, at any time. It’s a much less severe way of accomplishing the same goal.
There’s a clever extension, PureWikiDeletion, that displays links to blank pages as red, which solves the last part of letting blank pages mimic deleted pages. You can view it here:
https://www.mediawiki.org/wiki/Extension:PureWikiDeletion
Edit conflicts
Edit conflicts are less common than people who don’t edit wikis may think, but they do happen. An edit conflict occurs when person A saves a page while person B is still in the middle of editing that same page. When person B goes to save the page, MediaWiki will prevent the save from happening. Instead, Person B will get an error message indicating that there was an edit conflict, and they will see an interface showing both their version of the page and the latest version. At that point the user will have to manually merge their changes into the latest version.
Edit conflicts are another reason why it’s a good idea to edit a section of the page, instead of the entire page if you edit one section, and it’s not the section where someone else made their change, then there’s a good chance that your edit can go through without a conflict.
