Data Validation

Developers can extend this system to validate assets with custom-scripted rulesets.

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The editor features a Data Validation plugin for developers to validate assets with custom-scripted rulesets. Common validation use cases include:

  • Checking to make sure that assets meet name conventions

  • Enforcing space and performance budgets

  • Catching non-cyclic dependencies

Plugin Verification

To verify that the built-in Data Validation plugin is enabled by default, from the main menu, select Edit > Plugins , and from the Plugins menu, search for Data Validation .


Editor Usage

Developers can use the Data Validation system in many ways, from testing a single asset to validating all of a project's assets.

Validation Use Case




In the Content Browser, right-click an asset and select Asset Actions > Validate Assets

Validates a specific asset; however, it is possible to select multiple assets for validation.

Asset and dependencies

In the Content Browser, right-click an asset and select Asset Actions > Validate Assets and Dependencies

Validates a specific asset and its dependencies; however, it is possible to validate multiple assets at once.

Folder's assets

In the Content Browser, right-click a folder and select Validate Assets in Folder

Validates a specific folder; however, it is possible to validate multiple folders at once.

Project's assets

From the main menu, select File > Validate Data...

Validates all of the assets in a project's content directory.

Command Line Usage

Running the plugin from the command line is useful to developers who want to validate assets as part of a Continuous Integration System (CIS). Perform command line validation with the following commandlet:

UE4Editor-Cmd.exe <ProjectName>.uproject -run=DataValidation

  • The Data Validation system only runs C++ validation rules by default.

  • Developers can extend the Data Validation system to support Blueprint and Python validation rules.

Validation Rules

Currently, there are two ways to create validation rules:

  • Have a custom UObject-derived class that overrides IsDataValid . This works best for custom classes for your project.

    • This method provides access private/protected class data and functions that the UEditorValidatorBase method would not.

    • Because you're implementing your own class in this case, you can also set up a BlueprintImplementableEvent to be called by IsDataValid , so you can have some validation logic in C++ and further validation logic in Blueprints or Python.

  • Creating a UEditorValidatorBase derived class using C++, Blueprints, or Python. The two key functions here are CanValidateAsset and ValidateLoadedAsset , both of which take a UObject pointer as an argument to validate. This system lets you validate any asset, whether it's based on a default engine class or a custom class.

    • ValidateLoadedAsset must call AssetPasses or AssetFails for each of its execution paths.

    • Validators can be enabled by overriding IsEnabled . By default, this returns the protected variable bIsEnabled which is exposed to Details panels as well.

    • C++ and Blueprint validators will be discovered automatically on editor startup, while Python validators will need to register themselves with the UEditorValidatorSubsystem using AddValidator .

      • By default, Blueprint validator auto-registration is disabled in Fortnite for performance reasons.

Both types of validation are run by CIS, on asset save (enabled by default), and through menu options in the editor and Content Browser. When validation fails, messages will be displayed in the Message Log in the editor, and in the console in CIS.

If you are implementing your own calls to UEditorValidatorSubsystem , you will need to handle the display of the ValidationErrors FText array yourself. The functions needed to validate an asset from its FAssetData or the loaded UObject are available to scripting as well.

This section references these APIs, read them to learn more:

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