We will continuing using previous tutorial "Logistics" and add validator to show how to use this feature

## Add Validation to TransportGuide

Open your Visual Code and login. Open object **TransportGuide**.

Add to the existing property **documentNumber** the following validation rule:

  • Document Number must be filled

Find property **documentNumber** and bellow the property and the following code lines


  • **_value** reference the property in the scope.

If you return null, the validation engine will assume True.

Code above is the some as doing:



The result of the validation will be structured:

  • **IsValid** Boolean

  • **ErrorMessage** error validation message if **IsValid** is False

Also you can have global Validator that is associate with the Object (not with a Property).

Lets add global validation of the Object **TransportGuide**, where transport guide have to have at least one shipping guide.



The full code of the **TransportGuide** have to be:



## Download & Update Nuget packages

Build and download Nuget packages. _On build file ("Logistics") select "Download" (choosing directory where you want to download the files)_

Open your Visual Studio and the project previous created "Tutorial - Logistics".

Update the 2 Nuget packages on your Visual Studio project. _note: before updating, on command prompt (cmd), PowerShell or Package Manager Console of Visual Studio execute the command bellow_



_This clean nuget cache of the system, ensuring that version want is running_

## Use of Validaters

On class "Program.cs" add the following function:



Add call on "main" to the function that you have create.



Run the program and in the command prompt you should see the messages of the validations performed.

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The solution is available: [Source](🔗)