Validators

Db\RecordExists and Db\NoRecordExists Validators

Zend\Validator\Db\RecordExists and Zend\Validator\Db\NoRecordExists provide a means to test whether a record exists in a given table of a database, with a given value.

Installation requirements

Zend\Validator\Db\NoRecordExists and Zend\Validator\Db\RecordExists depends on the zend-db component, so be sure to have it installed before getting started:

$ composer require zendframework/zend-db

Supported options

The following options are supported for Zend\Validator\Db\NoRecordExists and Zend\Validator\Db\RecordExists:

• adapter: The database adapter that will be used for the search.
• exclude: Sets records that will be excluded from the search.
• field: The database field within this table that will be searched for the record.
• schema: Sets the schema that will be used for the search.
• table: The table that will be searched for the record.

Basic usage

An example of basic usage of the validators:

// Check that the email address exists in the database
$validator = new Zend\Validator\Db\RecordExists([
    'table'   => 'users',
    'field'   => 'emailaddress',
    'adapter' => $dbAdapter,
]);

if ($validator->isValid($emailaddress)) {
    // email address appears to be valid
} else {
    // email address is invalid; print the reasons
    foreach ($validator->getMessages() as $message) {
        echo "$message\n";
    }
}

The above will test that a given email address is in the database table. If no record is found containing the value of $emailaddress in the specified column, then an error message is displayed.

// Check that the username is not present in the database
$validator = new Zend\Validator\Db\NoRecordExists([
    'table'   => 'users',
    'field'   => 'username',
    'adapter' => $dbAdapter,
]);

if ($validator->isValid($username)) {
    // username appears to be valid
} else {
    // username is invalid; print the reason
    $messages = $validator->getMessages();
    foreach ($messages as $message) {
        echo "$message\n";
    }
}

The above will test that a given username is not in the database table. If a record is found containing the value of $username in the specified column, then an error message is displayed.

Excluding records

Zend\Validator\Db\RecordExists and Zend\Validator\Db\NoRecordExists also provide a means to test the database, excluding a part of the table, either by providing a WHERE clause as a string, or an array with the keys field and value.

When providing an array for the exclude clause, the != operator is used, so you can check the rest of a table for a value before altering a record (for example on a user profile form)

// Check no other users have the username
$user_id   = $user->getId();
$validator = new Zend\Validator\Db\NoRecordExists([
    'table' => 'users',
    'field' => 'username',
    'exclude' => [
        'field' => 'id',
        'value' => $user_id,
    ],
]);

if ($validator->isValid($username)) {
    // username appears to be valid
} else {
    // username is invalid; print the reason
    $messages = $validator->getMessages();
    foreach ($messages as $message) {
        echo "$message\n";
    }
}

The above example will check the table to ensure no records other than the one where id = $user_id contains the value $username.

You can also provide a string to the exclude clause so you can use an operator other than !=. This can be useful for testing against composite keys.

$email     = 'user@example.com';
$clause    = $dbAdapter->quoteIdentifier('email') . ' = ' . $dbAdapter->quoteValue($email);
$validator = new Zend\Validator\Db\RecordExists([
    'table'   => 'users',
    'field'   => 'username',
    'adapter' => $dbAdapter,
    'exclude' => $clause,
]);

if ($validator->isValid($username)) {
    // username appears to be valid
} else {
    // username is invalid; print the reason
    $messages = $validator->getMessages();
    foreach ($messages as $message) {
        echo "$message\n";
    }
}

The above example will check the users table to ensure that only a record with both the username $username and with the email $email is valid.

Database Schemas

You can specify a schema within your database for adapters such as PostgreSQL and DB/2 by supplying an array with table and schema keys, as demonstrated below:

$validator = new Zend\Validator\Db\RecordExists([
    'table'  => 'users',
    'schema' => 'my',
    'field'  => 'id',
]);

Using a Select object

It is also possible to supply the validators with a Zend\Db\Sql\Select object in place of options. The validator then uses this object instead of building its own. This allows for greater flexibility with selection of records used for validation.

use Zend\Db\Sql\Select;
use Zend\Validator\Db\RecordExists;

$select = new Select();
$select
    ->from('users')
    ->where->equalTo('id', $user_id)
    ->where->equalTo('email', $email);

$validator = new RecordExists($select);

// We still need to set our database adapter
$validator->setAdapter($dbAdapter);

// Validation is then performed as usual
if ($validator->isValid($username)) {
    // username appears to be valid
} else {
    // username is invalid; print the reason
    $messages = $validator->getMessages();
    foreach ($messages as $message) {
        echo "$message\n";
    }
}

The above example will check the users table to ensure that only a record with both the username $username and with the email $email is valid.