Apache Struts 2 Documentation > Home > Guides > Core Developers Guide > Validation > requiredstring validator |
RequiredStringValidator checks that a String field is non-null and has a length > 0. (i.e. it isn't ""). The "trim" parameter determines whether it will {@link String#trim() trim} the String before performing the length check. If unspecified, the String will be trimmed.
<validators> <!-- Plain-Validator Syntax --> <validator type="requiredstring"> <param name="fieldName">username</param> <param name="trim">true</param> <message>username is required</message> </validator> <!-- Field-Validator Syntax --> <field name="username"> <field-validator type="requiredstring"> <param name="trim">true</param> <message>username is required</message> </field-validator> </field> </validators>