Difference between #3 and #4 of
How to avoid a database update if the ActiveRecord was not modified

Revision #4 has been created by tomvdp on Apr 25, 2014, 1:49:04 PM with the memo:

added code that handles null values
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Title unchanged

How to avoid a database update if the ActiveRecord was not modified

Category unchanged

How-tos

Yii version unchanged

Tags unchanged

active record, database

Content changed

[...]
{
if($this->getIsNewRecord())
throw new CDbException(Yii::t('yii','The active record cannot be updated because it is new.'));
if($this->beforeSave())
{
if ($this->detectDirty && $this->_originalHash == $this->calculateHash(true)) {
$this->_isWritten = false;
if ($this->doAfterSaveIfNotDirty)
[...]
/**
* Calculate a hash from the model's attributes.
     * It excludes attributes in neverMakeDirtyAttributes.
 
     * If $castEmpty=true it will typecast empty string values to null if the matching database field is not a string.
 
     * That is what the Yii framework does when saving, so we need to mimic this here to be able to compare attributes after load and before save.
 
     * See {@see CActiveRecord::createUpdateCommand}.
 
     * @param boolean $castEmpty
 
 * @return string */ private function calculateHash($castEmpty = false) { $a = array_diff_key($this->getAttributes(false), array_flip($this->neverMakeDirtyAttributes)); return md5(serialize($a))if ($castEmpty) {
 
            $a = $this->typeCastEmpty($a);
 
        }
 
        return md5(serialize($a));
 
    }
 
    
 
    /**
 
     * Any empty attributes (value==='') for non-string database fields are translated into null.
 
     * @param array $a
 
     * @return array
 
     */
 
    private function typeCastEmpty($a) {
 
        $table=null;
 
        foreach($a as $k=>$v) {
 
            if ($v==='') {
 
                if ($table===null)
 
                    $table=$this->getTableSchema();
 
                $column = $table->getColumn($k);
 
            if($column->allowNull && $column->type!=='string')
 
                    $a[$k]=null;
 
            }
 
        }
 
        return $a;
}
}
```
[...]
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Viewed: 27 511 times
Version: 1.1
Category: How-tos
Tags: active record, database
Written by: tomvdp
Last updated by: tomvdp
Created on: Apr 24, 2014
Last updated: 10 years ago
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