xPDOObjectExistsValidationRule

What Does the Rule Do?¶

This rule checks whether another object exists. If that object doesn’t exist, validation on the current object fails. The object is specified by the className and pk attributes in the rule schema definition.

[!NOTE] pk is a fixed value written into the schema, not a reference to a field of the object being validated. The rule therefore always checks the same row, which is rarely what you want. To validate the current object’s field, use the xPDOForeignKeyConstraint rule instead.

Using the Rule¶

First, our model:

<model package="Test" baseClass="xPDO\Om\xPDOObject" platform="mysql"
    defaultEngine="InnoDB" version="3.0">
    <object class="myTest" table="test" extends="xPDO\Om\xPDOSimpleObject">
        <field key="name" dbtype="varchar" precision="255"
            phptype="string" default="" null="false" />

        <validation>
            <rule field="name"
                name="chunkExists"
                type="xPDOValidationRule"
                rule="xPDOObjectExistsValidationRule"
                pk="12"
                className="MODX\Revolution\modChunk"
                message="The Chunk does not exist, so this object cannot be saved."
            />
        </validation>
    </object>
</model>

Generate the model from the XML schema, then validate an object in a Snippet:

$output = '';
$modx->addPackage('Test', '/path/to/components/test/model/');
$obj = $modx->newObject('Test\myTest');
$validator = $obj->getValidator();
if (!$validator->validate()) {
    foreach ($validator->getMessages() as $errorMsg) {
        $output .= $errorMsg['message'];
    }
}
return $output;

This will display:

The Chunk does not exist, so this object cannot be saved.

See Also¶

1. xPDOForeignKeyConstraint
2. xPDOMaxLengthValidationRule
3. xPDOMaxValueValidationRule
4. xPDOMinLengthValidationRule
5. xPDOMinValueValidationRule
6. xPDOObjectExistsValidationRule