Field validators

Validators ensure that field input is entered in correct format and length. For example, you can validate that an email address adheres to a syntax such as first.last@company.com. You can add multiple validators to a field. The validators are executed like a chain, one after the other.

Common validator properties

Simple validator definition:

form:
  tabs:
    - name: tabUser
      label: User info
      fields:
        - name: emailAddress
          class: info.magnolia.ui.form.field.definition.TextFieldDefinition
          label: Email
          validators:
            - name: email
              class: info.magnolia.ui.form.validator.definition.EmailValidatorDefinition
              errorMessage: Enter a valid email address

Node name	Value
form
tabs
tabUser
fields
emailAddress
validators
email
class	info.magnolia.ui.form.validator.definition.EmailValidatorDefinition
errorMessage	Enter a valid email address
class	info.magnolia.ui.form.field.definition.TextFieldDefinition
label	Email

Properties:

`<field name>`	Name of field.
`validators`	required Contains the validator definition.
`<validator name>`	required Arbitrary node name. Use a name that describes the validator type.
`class`	required Validator definition class. Use the fully-qualified class name.
`factoryClass`	optional Fully qualified name of the Java class that creates the validator. The class must implement FieldValidatorFactory . Validator definitions specify a default factory class, meaning that unless you want to use a custom implementation you don't need to configure a factory class.
`errorMessage`	optional Text displayed to the user on invalid input. Text string or message bundle key.
`i18nBasename`	optional Message bundle for localized messages. This property can be set at dialog, form, tab or field level.
`pattern`	required for regex validation Regular expression pattern when using the `info.magnolia.ui.form.validator.definition.RegexpValidatorDefinition` class

List of validator definition classes

`info.magnolia.ui.form.validator.definition.RegexpValidatorDefinition`	Validates a regular expression given in the `pattern` property.
`info.magnolia.ui.form.validator.definition.EmailValidatorDefinition`	Validates an email address. Delegates to a Vaadin `EmailValidator` .

Custom regular expressions

The easiest custom validator is a regular expression. Use the RegexpValidatorDefinition class and define your own regular expression in the pattern property.

Here is an example of validating a ZIP code (U.S. postal code).

form:
  tabs:
    - name: tabUser
      label: User info
      fields:
        - name: zipCode
          class: info.magnolia.ui.form.field.definition.TextFieldDefinition
          label: Zip code
          validators:
            - name: zip
              class: info.magnolia.ui.form.validator.definition.RegexpValidatorDefinition
              pattern: ^\d{5}(-\d{4})?$
              errorMessage: Enter a valid U.S. ZIP code using the format 12345 or 12345-1234

Node name	Value
form
tabs
tabUser
fields
zipCode
validators
zip
class	info.magnolia.ui.form.validator.definition.RegexpValidatorDefinition
errorMessage	Enter a valid U.S. ZIP code using the format 12345 or 12345-1234
pattern	^\d{5}(-\d{4})?$
class	info.magnolia.ui.form.field.definition.TextFieldDefinition
label	Zip code

Custom validators

To write your own validator class:

Create a validator class that performs the actual validation.
Create a validator factory class that extends AbstractFieldValidatorFactory . Implement the createValidator method.
Create a validator definition class that extends ConfiguredFieldValidatorDefinition . In the definition class, set the factory class.

Example: Checking that a username is unique.

UniqueUserNameValidator
UniqueUserNameValidatorFactory
UniqueUserNameValidatorDefinition

Checking for null values

Best practice

Define default values for fields or check for null values. This ensures that you can submit the form. For example, if you define an optional option group field field and don't provide a default value, an error occurs when a user submits the form by mail. The email processor does not check for null value in the template. It is good practice to check for null values of any variables you call.

You can check for null values and provide a default value in a Freemarker script like this:

field: ${field!"value not provided"}

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