View source for AtkMetaNode

{{class|atk}}

== Description ==

The atkMetaNode is a derivative of [[atkNode]]. Its main feature is the fact that it derives most of its functionality from the database metadata.

If this is a regular node:

<syntaxhighlight lang="php">
  useattrib("atktextattribute");
  
  class project extends atkNode
  {
    function project()
    {
      $this->atkNode("project"); 
      $this->add(new atkAttribute("id", AF_AUTOKEY));
      $this->add(new atkAttribute("name"));
      $this->add(new atkTextAttribute("description"));
  
      $this->setTable("project");
    }
  }
</syntaxhighlight>

Then this would get you exactly the same result:

<syntaxhighlight lang="php">
  class project extends atkMetaNode {}
</syntaxhighlight>

In this example, atkMetaNode would find a table called 'project', look in the database metadata, find out that there's an id and name field, and do the rest automatically.

==atkMetaNode tutorial==

A comprehensive tutorial on the atkMetaNode can be found in [[Using_the_atkMetaNode|the atkMetaNode Howto]]

==Properties==

The atkMetaNode supports several properties that can be set to influence behaviour.

An example of this is the property $flags that can be used to define the default flags:

<syntaxhighlight lang="php">
  class project extends atkMetaNode
  {
    protected $flags = array(NF_READONLY);
  }
</syntaxhighlight>

The following properties are available:
;table          :table name
;sequence       :sequence name
;db/database    :database name or instance
;policy         :meta policy, the meta policy to use ((sub-)class [[atkMetaPolicy]] instance)
;grammar        :meta compiler, the meta compiler to use ((sub-)class [[atkMetaCompiler]] instance)
;handler        :meta handler, handler which needs to be called instead of the default meta method
;flags          :The [[Node Flags]]
;descriptor     :descriptor template for this node
;order          :(default) order to sort fields
;index          :create indexed navigation on a attribute/fieldname
;filter         :filter
;securityAlias  :security alias for this node
;securityMap    :security map for this node (will be added to the existing security map!)

==Frequently Answered Questions==

=== Why do I get "Fatal error: Can not extend non-existing class 'atkMetaNode' in ..."? ===

The atkMetaNode is not included by default (to save resources for scripts not using it). In the class where you need it, you can add the following line:

<syntaxhighlight lang="php">
  atkimport("atk.atkmetanode");
</syntaxhighlight>

If you use it heavily, and don't mind that it's always included, you can put this line in your atk.inc file instead.

=== My table is "tbl_project" but my node should be called "project". Can I still use the atkMetaNode? ===

Yes:

<syntaxhighlight lang="php">
  class project extends atkMetaNode
  {
    protected $table = "tbl_project";
  }
</syntaxhighlight>

=== How can I set flags on an attribute? === 

<syntaxhighlight lang="php">
  class project extends atkMetaNode
  {
    function meta(&$policy)
    {
      $policy->setFlags("name", "description", AF_SEARCHABLE);
    }
  }
</syntaxhighlight>

=== How can I set flags on the node itself? ===
 
<syntaxhighlight lang="php">
  class project extends atkMetaNode
  {
    var $flags = NF_LOCK;
  }
</syntaxhighlight>

This only works for a single flag because PHP won't accept the '|' symbol in a variable declaration. If you need multiple flags, use:

<syntaxhighlight lang="php">
  class project extends atkMetaNode
  {
    var $flags = array(NF_LOCK, NF_EDITAFTERADD);
  }
</syntaxhighlight>

=== How can I change the type of attribute that the metanote has decided to use? ===

<syntaxhighlight lang="php">
  function meta(&$policy)
  {
    $policy->setType("description", "atkFckAttribute");
  }
</syntaxhighlight>

=== How can I use tabs in the atkMetaNode? ===

<syntaxhighlight lang="php">
  function meta(&$policy)
  {
    $policy->setTab("description", "advanced");
  }
</syntaxhighlight>