SilverStripe唯一URL（调试）

Question

In this DataObject there is a user supplied field Title which has to be converted to a unique URL slug.

Desired Result: Duplicate URL's should get a suffix to its value. So saving 2 records with Title Foo should result in one record with foo as its value for column URL and the second record should have value foo-2 for the same column.

public function onBeforeWrite() {
    parent::onBeforeWrite();

    // Sanitize Title field to use for URL
    $filter = URLSegmentFilter::create();
    $this->URL = $filter->filter($this->Title);

    // If URL is not unique, add suffix
    $i = 1;
    while($this->uniqueURL($this->URL)) {
        $i++;
        $this->URL = $this->URL . "-" . $i;
    }   
}

method: uniqueURL (within same class)

public function uniqueURL($URL) {

    // Check if there is a record with the same URL
    $existingURL = DataObject::get('NewsArticle', "URL = '$URL'");
    if ($existingURL) {
        // this is a duplicate URL
        return false;
    } else {
        // this is a unique url
        return true;
    }
}

Saving Foo twice would result in foo and foo-2.

When saving two records with the same Title Foo results in two URL fields with foo

Answer 1

Why do you have two foo urls?

If you check your DB before inserting all records, this means that the check will not work on your record batch.

Don't use a loop to count unique urls

You don't need to loop and check every time and increment the count ($i). Performance wise youre far better off doing a COUNT() in a query and just use that value for your next insert.

// The following does exactly the same with just 1 query. No loop needed.
$count = DB::query("SELECT COUNT(*) FROM Table WHERE Title LIKE '{$filteredTitle}'")->value();
if ($count > 1) {
    $filteredTitle .= "-" .  $count;
}
$this->URL = $filteredTitle

Solutions

To do it onBeforeWrite() the only possibility is to Query your data AND check your records before they are saved.

Or a simpler solution with the same results is that you can change the url in an onAfterWrite() , and check use the amount of same titles as number.

public function onAfterWrite() {
    parent::onAfterWrite();

    // Sanitize Title field to use for URL
    $filter = URLSegmentFilter::create();
    $filteredTitle= $filter->filter($this->Title);

    $count = DB::query("SELECT COUNT(*) FROM Table WHERE Title LIKE '{$filteredTitle}'")->value();
    if ($count > 1) {
        $filteredTitle .= "-" .  $count;
    }
    $this->URL = $filteredTitle
}