#Field error state

FieldError puts a field in an error state. The border and the label of the field get the danger color, and an error Callout next to the field says what is wrong. Use it for a required field that is empty, or for a value that is not valid. It works with each Unity field and each toolbox field.

How to mark a required field:

saveButton.clicked += () =>
{
    if (string.IsNullOrWhiteSpace(nameField.value))
    {
        FieldError.Show(nameField, "Enter a user name.");
        return;
    }
    FieldError.Clear(nameField);
    save();
};

How to remove the error when the user types:

nameField.RegisterValueChangedCallback(_ => FieldError.Clear(nameField));

How to show the error state with no callout (for example, when a label below the form has the message):

FieldError.Show(mailField);

In a Wizard, give the field to ShowValidationError. The wizard sets and clears the error state for you:

wizard.GetStep("user").Validator = _ =>
{
    if (nameField.value.Length > 0) return true;
    wizard.ShowValidationError("Enter a user name.", nameField);
    return false;
};

• The error state stays until Clear. A value change does not remove it.
• The callout follows the field, and it closes when the field leaves the panel, for example when its window closes. Escape closes a callout only when it has the focus; a callout with only text does not take the focus.
• The callout moves to the opposite side when the workspace has no room.
• Show with a message needs a field that is in a panel.

#Styling