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StringLength

This validator allows you to validate if a given string is between a defined length.

Zend_Validate_StringLength supports only string validation

It should be noted that Zend_Validate_StringLength supports only the validation of strings. Integers, floats, dates or objects can not be validated with this validator.

Supported options for Zend_Validate_StringLength

The following options are supported for Zend_Validate_StringLength:

  • encoding: Sets the ICONV encoding which has to be used for this string.

  • min: Sets the minimum allowed length for a string.

  • max: Sets the maximum allowed length for a string.

Default behaviour for Zend_Validate_StringLength

Per default this validator checks if a value is between min and max. But for min the default value is 0 and for max it is NULL which means unlimited.

So per default, without giving any options, this validator only checks if the input is a string.

Limiting the maximum allowed length of a string

To limit the maximum allowed length of a string you need to set the max property. It accepts an integer value as input.

<?php
$validator 
= new Zend_Validate_StringLength(array('max' => 6));

$validator->isValid("Test"); // returns true
$validator->isValid("Testing"); // returns false

You can set the maximum allowed length also afterwards by using the setMax() method. And getMax() to retrieve the actual maximum border.

<?php
$validator 
= new Zend_Validate_StringLength();
$validator->setMax(6);

$validator->isValid("Test"); // returns true
$validator->isValid("Testing"); // returns false

Limiting the minimal required length of a string

To limit the minimal required length of a string you need to set the min property. It accepts also an integer value as input.

<?php
$validator 
= new Zend_Validate_StringLength(array('min' => 5));

$validator->isValid("Test"); // returns false
$validator->isValid("Testing"); // returns true

You can set the minimal requested length also afterwards by using the setMin() method. And getMin() to retrieve the actual minimum border.

<?php
$validator 
= new Zend_Validate_StringLength();
$validator->setMin(5);

$validator->isValid("Test"); // returns false
$validator->isValid("Testing"); // returns true

Limiting a string on both sides

Sometimes it is required to get a string which has a maximal defined length but which is also minimal chars long. For example when you have a textbox where a user can enter his name, then you may want to limit the name to maximum 30 chars but want to get sure that he entered his name. So you limit the mimimum required length to 3 chars. See the following example:

<?php
$validator 
= new Zend_Validate_StringLength(array('min' => 3'max' => 30));

$validator->isValid("."); // returns false
$validator->isValid("Test"); // returns true
$validator->isValid("Testing"); // returns true

Setting a lower maximum border than the minimum border

When you try to set a lower maximum value as the actual minimum value, or a higher minimum value as the actual maximum value, then an exception will be raised.

Encoding of values

Strings are always using a encoding. Even when you don't set the encoding explicit, PHP uses one. When your application is using a different encoding than PHP itself then you should set an encoding yourself.

You can set your own encoding at initiation with the encoding option, or by using the setEncoding() method. We assume that your installation uses ISO and your application it set to ISO. In this case you will see the below behaviour.

<?php
$validator 
= new Zend_Validate_StringLength(
    array(
'min' => 6)
);
$validator->isValid("Ärger"); // returns false

$validator->setEncoding("UTF-8");
$validator->isValid("Ärger"); // returns true

$validator2 = new Zend_Validate_StringLength(
    array(
'min' => 6'encoding' => 'UTF-8')
);
$validator2->isValid("Ärger"); // returns true

So when your installation and your application are using different encodings, then you should always set an encoding yourself.

Zend Framework