# Validation Node
The **Validation Node** is a built‑in **Custom Extension** provided by ONEWEB that enables developers to **validate data within Business Objects (BO)** during the execution of **Microflows** or **Process Flows**.\
This node helps ensure **data quality, completeness, and correctness** before data is processed further, persisted, or sent to external systems.
By centralizing validation logic in a dedicated node, ONEWEB helps reduce duplicated checks and improves the consistency of integration and workflow behavior.
***
### Purpose of Validation Node
The Validation Node is designed to:
* Validate one or more Business Objects against defined rules
* Enforce data quality consistently across integration flows
* Prevent invalid or incomplete data from propagating through the system
* Produce structured and reusable validation error messages
* Reduce duplication of validation logic across Microflows and Processes
#### Typical Use Cases
* Validating user input before database insert or update operations
* Ensuring mandatory fields exist before invoking external services
* Validating batch or imported data (for example, data read from Excel files)
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### Installing the Validation Node Extension
Before the Validation Node can be used, the extension must be **installed and enabled** in the application.
To install the extension:
* Follow the steps described in **Section 6.4.16 – Custom Extensions**
* Install and enable the **Validation Node** extension for the target application
Once installed:
* The Validation Node appears in the **diagram palette**
* It can be used like any other standard activity node in Microflow or Process Designer
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### Configuring Validation Rules
Validation behavior is defined through the **Extension Properties** of the Validation Node.\
Multiple validation conditions can be configured and evaluated together.
#### Logical Operators
The Validation Node supports two logical operators for evaluating multiple rules:
* **AND**\
All validation conditions must be satisfied for the validation to pass
* **OR**\
Validation passes if at least one condition is satisfied
The selected operator determines how validation rules are combined and evaluated during execution.
Validation results—including error messages—are produced as **structured output**, which can be consumed by downstream logic.
***
### Input Mapping (Business Objects)
All Business Objects that require validation must be mapped as **input** to the Validation Node.
Input configuration allows developers to:
* Select one or more Business Objects for validation
* Map existing Business Objects using lookup functionality
* Validate multiple Business Objects within a single node execution
This enables centralized validation across complex data models.
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### Output Mapping (Validation Messages)
The Validation Node produces **structured validation output**, which can be mapped and consumed in different ways.
Validation results can be:
* Mapped to output Business Objects
* Evaluated using a **Gateway Node**
* Returned to UI components (Smart Form or Page Designer)
* Logged or persisted for audit and tracking purposes
This makes validation feedback easy to integrate into both backend logic and user‑facing flows.
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### Using Validation Results in Flow Logic
Validation output can be integrated into flow logic using common patterns, such as:
* Branching execution paths using a Gateway Node
* Stopping further processing when validation fails
* Returning validation messages directly to the UI
* Combining validation with Error or Timer handling
The Validation Node integrates seamlessly with both **Microflow** and **Process Flow** execution models.
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### Best Practices
To ensure clear and reliable validation behavior:
* Perform validation early in the flow execution
* Keep validation rules focused and easy to understand
* Use the Validation Node instead of duplicating validation logic across multiple nodes
* Always map and handle validation output messages
* Separate validation concerns from core business processing logic
Following these practices improves maintainability and reduces unexpected runtime failures.
***
### Summary
The **Validation Node** is a built‑in Custom Extension that enables **structured, reusable, and centralized data validation** in ONEWEB.
With the Validation Node, developers can:
* Validate one or more Business Objects in a single node
* Apply **AND / OR** logical evaluation of rules
* Produce consistent and structured validation feedback
* Control flow execution based on validation results
The Validation Node is an essential component for building **robust, reliable, and enterprise‑grade integration workflows** using **ONEWEB Microflow Designer** and **Process Designer**.
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