Field Validators

The validators that constrain what may be saved in a field.

Validators is an array, so a field may carry several. Each one constrains the stored value and accepts a Message shown when it fails. Validators run only on a value that is present - requiring a value is what IsRequired does.

Which validators suit which types is recorded on each validator.

Type	Summary
`alphanumeric`	The value must contain only letters and digits.
`decimal`	The value must be a decimal number.
`different`	The value must differ from the value of another named field of the same type.
`email`	The value must be a valid email address.
`eq`	The value must equal a given value.
`gt`	The value must be greater than a given value or another field's value.
`gte`	The value must be greater than or equal to a given value or another field's value.
`lt`	The value must be less than a given value or another field's value.
`lte`	The value must be less than or equal to a given value or another field's value.
`maxitems`	The field must hold at most a given number of entries.
`maxlength`	The value must be at most a given number of characters.
`maxsize`	An uploaded file must be no larger than a given number of bytes.
`minitems`	The field must hold at least a given number of entries.
`not`	The value must not equal a given value.
`number`	The value must be a whole number.
`phone`	The value must be a valid phone number.
`regex`	The value must match a regular expression.
`same`	The value must equal the value of another named field of the same type.
`url`	The value must be a valid URL.