Localize Validation Messages

• Feb 17, 2026
• 3 minutes to read

XAF applications can be localized to the required language. This topic explains localization of the validation messages that are shown to users when a rule is broken or the Validation Action is executed. Refer to the Localization Basics topic, to get general information on localization.

To localize validation messages, use the Model Editor invoked for the required language (see Localize UI Elements). In the sections below, you will learn which nodes should be localized.

Localize Message Text

Navigate to the Localization | Exceptions | UserVisibleExceptions | Validation node.

The child nodes represent the messages that are displayed by the Validation System in different contexts:

• ActionErrorMessageHeaderFormat

  A rule can be checked when a particular Action is executed. In this instance, the value of the corresponding ActionDesign | Actions | <Action> node’s ValidationContexts property should be set as the rule’s target context ID. When a rule is broken after the associated Action has been executed, a validation message is displayed. The text of this message is specified by the ActionErrorMessageHeaderFormat property. In this property, you can use the {0} format item. It will be replaced with the name of the executed Action.

• AllContextsErrorMessageHeader

  The Validation Module supplies the ShowAllContexts Action (see in Validation Rules topic). When this Action is executed, all rules that are specified for the current object are checked in all associated contexts. If at least one rule is broken, the displayed validation message contains the text specified by the AllContextsErrorMessageHeader property.

• DeleteErrorMessageHeader

  A rule’s context can be set to the DefaultContexts.Delete value. In this instance, the rule will be checked when deleting the target object. If the rule is broken, the displayed validation message will contain the text specified by the DeleteErrorMessageHeader property.

• SaveErrorMessageHeader

  A rule’s context can be set to the DefaultContexts.Save value. In this instance, the rule will be checked when saving the target object to the database. If the rule is broken, the displayed validation message will contain the text specified by the SaveErrorMessageHeader property.

• ValidationSucceededMessageHeader

  The Validation Module supplies the ShowAllContexts Action (see in Validation Rules topic). When this Action is executed, all rules that are specified for the current object are checked in all associated contexts. If all rules are valid, the displayed validation message contains the text specified by the ValidationSucceededMessageHeader property.

Write the appropriate localized text in the Value property of these nodes.

Localize Rule Description

Navigate to the Validation node.

To localize the text that describes a broken rule in the validation message, use one of the following approaches:

• The Validation | ErrorMessageTemplates node

  This node defines the message templates that are used for built-in rule types. To localize a message template for a certain rule type, use the corresponding Validation | ErrorMessageTemplates | RuleType node. In this node, use the required MessageTemplate… property. The localized text will be used for all rules of the corresponding type.

• The Validation | Rules node

  This node defines all the rules used in the current application. To localize a message template for a particular rule, use the corresponding Validation | Rules | Rule node. In this node, use the required MessageTemplate… property or the CustomMessageTemplate property. The localized text will be used for the current rule only.

In a message template, you can use format items. For instance, when using the {TargetPropertyName} format item, the caption of the validated property will be inserted in the rule description. For details, refer to the RuleBaseAttribute.CustomMessageTemplate property description.