Modifying the TCA
4. Figuring out what values to modify
To figure out what values we want to modify, we need to look at the current TCA configuration. One thing that always bugs me about the TYPO3 backend is that the groups field for frontend user records is only shows three values at a time. In both Firefox and Safari on the Mac, this field is small enough so that the arrow buttons don't show up on the select field, which inevitably confuses users. Let's go ahead and make this field a bit larger so we don't have to keep running into this problem. (I'm writing this on a PC, so you won't see the button problem I'm referring to in the screen shots, but go ahead and look at a frontend user record on a Mac and you'll see what I'm talking about.
Here's what the groups field currently looks like in a frontend user record:
Before we can make a change to the TCA, we need to figure out what the key is for this field in the TCA array. Luckily, TYPO3 makes this relatively easy to do. Click on the "Configuration" module in the backend (if you don't see it, you need to make sure that a) you're logged in as an admin and b) that the "lowlevel" extension is installed; see requirements, above). From the drop down menu, select "$TCA (tables.php)."
At this point, you should see the top level of a tree view of the TCA array. Each of these top level keys corresponds to a table in the TYPO3 database. If you want to change the TCA values for a core content element (such as text, text with image, list, etc), you're going to want to look for fields in tt_content. If you want to change values for an extension, look for a table with the extension key in the name (generally preceded by "tx_"). In our case, we're modifying the way frontend user records are displayed, so we want to expand the "fe_users" branch of the page tree.
Since we're looking to change the way a specific field (which corresponds to a specific column in the fe_users table) is displayed, the next step is to expand the "columns" branch of the fe_users TCA configuration. Doing this will bring up a list of all of the columns in the fe_users table. These columns correspond to the fields that show when you view a frontend user record in the backend. In our case, we want to modify how the usergroup field is displayed, so click on the plus sign next to "usergroup" to expand that branch.
We're almost there! At this point you should see a "config" section for the usergroup column. The config section is the part that holds most of the configuration for how the field is displayed. Expand it and get ready!
At last we can see the value we're looking for -- it's the "size" property, which is currently set to "3":
If you're still with me, take solace in the fact that we're almost done, and you'll soon be on your way to customizing TYPO3 to your hearts content. Go ahead and click on the "[size]" link. Clicking on the link will make TYPO3 output the position of this value in the $TCA variable, which is what we need to know in order to change it. Copy the value that TYPO3 returns so that you can add it to your ext_tables.php file.