What is a Prompt Before Validation Rule?

A Prompt Before Validation rule is a validation or rule check that can be performed prior to a business rule execution. Prompt Before Validation rules often include important information requests that can dictate how the form should be processed. Prompt Before Validation rules may also be used to notify the user of a potential problem with the form action being performed so they have the opportunity to resolve the problem prior to performing the form action step.

Technically, a Prompt Before Validation rule is a class implementing org.kuali.kfs.kns.rule.PromptBeforeValidation, which specifies a single method: boolean processPrompts(ActionForm form, HttpServletRequest request, PromptBeforeValidationEvent event)).

Why do we needPrompt Before Validation?

Prompt Before Validation rules are used to modify document data prior to business rule validation. This is useful for setting default values to document fields prior to validation, for example. They are also able to ask confirmation questions of the user before continuing on with validation and, if validation is successful, routing.

When are Prompt Before Validation rules invoked?

By default, Prompt Before Validation rules are automatically invoked when approving, blanket approving, routing, or performing a route report on a document. They are typically invoked prior to business rule validation and document persistence/routing. For more information, consult KualiDocumentActionBase.

Modifying control flow using Prompt Before Validation rules

As noted in the previous section, Prompt Before Validation rules are automatically invoked by the framework before executing document actions. Upon completion of the Prompt Before Validation rules check (i.e. calling PromptBeforeValidation.processPrompts(...)), the following may occur (see KualiDocumentActionBase.promptBeforeValidation(...)):

processPrompts(...) returns true: checks succeeded and the action (e.g. routing) may continue
processPrompts(...) returns false:checks failed and we may need to either not continue processing (i.e. go back to the original form), render some other action forward (i.e. another JSP page), or ask a question

How to Create and Add a Prompt Before Validation Rule Check

Step 1 Creating a Prompt Before Validation rule class

org.kuali.kfs.coa.document.validation.impl.ObjectCodePreRules is a good example of how it works. Prompt Before Validation classes extend org.kuali.kfs.kns.rules.PromptBeforeValidationBase, or (far more rarely!) implement org.kuali.kfs.kns.rules.PromptBeforeValidation directly. If PromptBeforeValidationBase.java is extended, the only method that needs to be overridden is doPrompts() which takes in a document and returns true if the check completed successfully. If this method returns false, the current action will be halted and control determined by the state of the PromptBeforeValidationEvent object. (See the PromptBeforeValidationEventdocumentation below for more details.) Otherwise, the requested action continues.

Setting values in a document

This section will describe how to use Prompt Before Validation rules to set values on a document prior to validation. In this example, a document has a "userId" field, and if it's blank, the system will automatically fill in a default value.

public boolean doPrompts(Document document) {
    MyDocument myDocument = (MyDocument) document;
    if (StringUtils.isBlank(myDocument.getUserId())) {
        myDocument.setUserId("someDefaultValue");
    }
    return true;
}

Note that in this case, the doPrompts(Document) method returns true, indicating that business rules validation should occur with whatever values are set.

Asking a yes/no question

This section will describe how to use Prompt Before Validation rules to ask a user a question that requires a yes/no response when the Prompt Before Validation rules are invoked. In this example, a document has a "name" field on it, and the system will ask the user a question to confirm if he wants to submit with a blank name.

public boolean doPrompts(Document document) {
    boolean preRulesOK = true;
    preRulesOK &= conditionallyAskQuestion(document);
    return preRulesOK;
}

private static final String questionTextPropertyKey = "questionForBlankName";
private static final String questionId = "mySampleQuestionId";

private boolean conditionallyAskQuestion(Document document) {
    MyDocument myDocument = (MyDocument) document;
    boolean shouldAskQuestion = StringUtils.isBlank(myDocument.getName());

    if (shouldAskQuestion) {
        String questionText = SpringContext.getBean(KualiConfigurationService.class).getPropertyString(questionTextPropertyKey);
        boolean confirmBlankName = super.askOrAnalyzeYesNoQuestion(questionId, questionText);
        if (!confirmBlankName) {
            super.abortRulesCheck();
        }
    }
    return true;
}

In the conditionallyAskQuestion(Document) method, the following steps occur:

We determine whether the condition that requires asking a question is true. In our example, whether the "name" field of the document is blank.
If it's true, then we go into the KualiConfigurationService to retrieve the text of the question (e.g. "Are you sure you want to submit with a blank name?").
We call the askOrAnalyzeYesNoQuestion(String, String) method. It does one of things:
1. If the question has not yet been asked, it throws an exception. This exception is caught by the framework and it forwards to the question page.
2. If the answer to the question is "yes", then this method returns true.
3. If the answer to the question is "no", then this method returns false.
If the askOrAnalyzeYesNoQuestion(String, String) returned a value (i.e. no exception), then we determine how to proceed. In the example, if the user answered "no", then we abort business rule validation and send the user back to the document. Another way of accomplishing this is to make doRules{Document) return false.

Step 2 Specify Prompt Before Validation Rules class in Document data dictionary file.

Specifying a Prompt Before Validation rule implementation for transactional and maintenance documents are essentially identical. In the document's data dictionary, specify the promptBeforeValidationClassclass name inside of a promptBeforeValidationClass property(see maintenance document and transactional document documentation).

<property name="promptBeforeValidationClass" value="org.kuali.kfs.module.cam.document.validation.impl.AssetPaymentDocumentPreRules"/>

PromptBeforeValidationEvent

Like other Events, this class is initially populated with the current Document object for the rules to examine. However, special properties exist in this event that indicate to the Action class how to handle the request if the rule check returns false (stop action request).

performQuestion: boolean indicating that we should forward to the question framework for user input. If this is set, the following additional properties are examined to build the question:
- questionId: Unique identifier for the question. Helpful if a series of questions or prompts need to occur
- questionText: Text that should appear on question screen. Note: the best practice is to store the text in to a application resources file (i.e. accessible using the KualiConfigurationService.getPropertyString(String) method) and to retrieve the value prior to setting this property.
- questionType: Indicates what type of question this is. E.g., Yes/No, OK/Cancel, ..
- questionCaller: Caller identifier for the question framework for returning response. This is typically the name of the action that was being performed that's invoking the question.
- questionContext: Any additional context the Prompt Before Validation class needs to have returned along with the user response
- returnActionFoward: the name Struts action forward mapping to forward to. Note this can be the basic mapping which would return the user back to the document, most likely with additional messages.
  
  For additional information on events, see the Event documentation.
  
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