Adding custom (programmatic) field validation to a form in InfoPath 2007 is quite easy. Firstly make sure you have set your programming language of choice by going to the Tools menu then “Form Options” -> “Programming”, and then selecting your preferred language under “Form template code language”. For this example i am going to be using C#.
Back in your form design window right-click on the field you wish to validate, and select “Programming” -> “Validating Event”. This will open a “Visual Studio Tools for Applications” (VSTA) window, and generate the following code snippet:
public void myFieldName_Validating(object sender, XmlValidatingEventArgs e)
{
// Write your code here.
}
Obviously this code is not doing any validation yet, we just need to insert our validation code in place of the “your code here” comment. Let us try a simple validation of ensure the data entered in the field is at least 3 characters long with the following code.
public void myFieldName_Validating(object sender, XmlValidatingEventArgs e) {
//Check the Length of the NewValue of the field
if (e.NewValue.Length < 3) {
//Report the validation error back to the client on the form
e.ReportError(e.Site, false, "Please Enter a valid MyField");
}
}
As mentioned in the comments e.NewValue retrieves the ‘New’ value that is being entered/inserted into the field before it has been set and e.ReportError sends any validation errors back to the form for the client (read the MSDN article for details on the parameters of ReportError).
Unfortunately there is a minor issue with this basic piece of code and that is due to the fact that the validating event also gets fired during the loading of the form and as shown in this kb article we need to check the XmlOperation that is being performed when the validation is fired. This means updating our code to the following.
public void myFieldName_Validating(object sender, XmlValidatingEventArgs e) {
//Ensure validation is only done when inserting or changing a value
if (e.Operation == XmlOperation.Insert || e.Operation == XmlOperation.ValueChange) {
//Check the Length of the NewValue of the field
if (e.NewValue.Length < 3) {
//Report the validation error back to the client on the form
e.ReportError(e.Site, false, "Please Enter a valid MyField");
}
}
}
Save your code changes and while still in VSTA build the project to ensure you don’t have any coding errors (Ctrl+Shift+B, or from the menu “Build” -> “Build ‘MyFormName’”). If you get a “Build succeeded” message in the status bar you can close the VSTA window and then preview your form to see your validation in action.
