Using a preAdd trigger on a hidden attribute
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ATK Howto: Using a preAdd trigger on a hidden attribute
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Issue
I wanted to use the news table in my database for 2 sections of the website (backend and frontend). So I added a field called "is_backend" to the table "news".
The most userfriendly solution for editing this table was to create 2 nodes. I called those notes "news_backend" and "news_site".
Because both the "news_site" and "news_backend" contained the same fields I created a base "news" node containing all the basic fields. The "news_site" and "news_backend" are extending the "news" node. I wanted to add a filter on the "is_backend" field so the right items would show up in the admin-view.
I also wanted to fill the "is_backend" field with either "0" or "1". I tried to use the preAdd functionality for this but it wasn't working the way I expected. That's why I wrote this HowTo to share the solution for this problem.
Code
See the comments in the code for an explanation.
class news extends atkNode {
function news($type="news",$flags=0) {
// The $type is important, otherwise the links in the admin
// view will goto this node instead of to the child node
$this->atkNode($type, NF_ADD_LINK);
$this->add(new atkAttribute("news_id", AF_AUTOKEY));
$this->add(new atkAttribute("title", AF_SEARCHABLE));
$this->add(new atkTextAttribute("text", AF_SEARCHABLE|AF_HIDE_LIST));
// You have to add the is_backend property to the parent node
// because otherwise you can't use it in the preAdd function.
$this->add(new atkBoolAttribute("is_backend"));
$this->setTable("news");
}
}
The "news_backend" is almost the same as the "news_site" node, just replace the 1's with 0's :).
// Import the parent node, otherwise you can't extend it
// "modules" is the name of the modules directory and
// "inhoud" the name of the module
atkimport("modules.inhoud.news");
class news_backend extends news {
function news_backend() {
// Call constructor of parent node with the name of the current node
// so the atkNode function can be called with the right node name
parent::news("news_backend");
// This filter takes care of only showing the items with the is_backend
// field set to '1'.
$this->addFilter("is_backend","1");
// This is basically the trick; hide the is_backend field that is created
// in the parent node.
$attr = &$this->getAttribute("is_backend");
$attr->addFlag(AF_HIDE);
}
// preAdd function, will only work if the "is_backend" field is present
// and visible(!) in the parent node.
function preAdd(&$record) {
$record["is_backend"] = 1;
}
}
Comments
Feel free to correct my English grammar :).