EntrySet.Extenders Namespace

ValidationExtender Component

ValidationExtender helps developers with data entry validation. For any control on a form validation can be defined, which can consist of one or any number and combination of so called Validators. Next to typical validators for value comparison, datatype checks, regular expression etc there is special Condition validator that is able to validate value based on a formula and values from other controls.

ValidationExtender adds to edit controls validation functions. Once ValidationExtender is placed on a form with textboxes on it for example, then these textboxes receives new properties, Validators which are used to set validation conditions. ValidationExtender works with virtually any editing type such as ListBox, ComboBox and or Checkbox. To validate values there are two modes - Automatic and Manual. In Automatic mode validation is done on the fly while user is typing values into a control. In Manual mode validation must be done using Validate() method of ValidationExtender. To indicate invalid value there are following possibilities to choose from - ErrorProvider, MessageBox or AlertBox.

Validator Types

Compare Validator
Compares two controls' values or value in a control with a specific value.

Condition Validator
Checks whether a formula condition is valid. For example [MonthBudget]>=[Price]*[Quantity] where MonthBudget, Price, Quantity are Ids of items on a form.

DataType Validator
Checks the data type validity of a value entered, for example that value is type of Date.

Expression Validator
Checks value against the regular expression.

Length Validator
Validates length of entered value.

List Validator
Checks whether entered value is within a specified list of values.

Range Validator
Validates that entered value is within a specific range of values.

Required Validator
identifies that a value is required or not.

Event Handling
There are three events available for you to control and modify the validation process - ControlValidating, ControlValidated and ValidateControlError.

Validation Mode

For value validation two modes can be used - Automatic and Manual. Mode can be set in ValidationMode property If you set Automatic mode, the validation will be executed automatically during value entry into form If you set Manual mode, you have to execute the validation by Validate () Method. Using this method you can also execute the validation of sole control, e.g. Validate (TextBox1).

Error Mode

For indication of invalid values you can choose one of several procedures. The way of indication is to be set in ErrorMode.Mode property. These possibilities are available:

None
No indication is executed. This possibility is chosen in case that you want to indicate invalid value by your own way.

ErrorProvider
Indication is executed through ErrorProvider class. Indication has default image of little red circle with exclamation mark inside, which is displayed next to control with invalid value. If the user goes on this circle with mouse cursor, description of error will be displayed. The description is set in ErrorText property. Image of ErrorProvider can be influenced by ErrorMode.Style.ErrorProvider style.

MessageBox
Indication is executed by displaying of message box, which contains the description of all incorrect values. This description can be set in ErrorText property.

AlertBox
Indication is executed by displaying of popup alert box in right bottom corner of a screen. Alert box contains description of incorrect values, which is to be set in ErrorText property. If the description is too long, only its part will be displayed and after mouse click on the description the message box with complete description will be displayed.

Error Text

For description of invalid values ErrorText property can be used. It can be found at every Validator. This allows you to set different error alert for each type of validation.

If the ErrorText is not set at validator, global error text is used. It is set at ValidationExtender in GlobalErrorTexts property.

Into error texts special variables %ItemId% and %ItemName% can be entered. It will be replaced in displayed text by values, which are set in ItemId and ItemName properties of validated control. Text can look e.g. like this:

%ItemName% field contains incorrect value.

Testimonials

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