# Hidden
The **Hidden** field is used to store **hidden values** within a Smart Form.\
It is not visible to end users but plays an important role in **data handling, internal logic, and process integration**, such as storing IDs, keys, or system‑controlled values.
Hidden fields are commonly used to maintain contextual or technical data without exposing it on the UI.
***
### Purpose of Hidden Field
The Hidden field is designed to:
* Store internal identifiers (e.g. primary keys, foreign keys)
* Maintain system‑generated or derived values
* Support data manipulation without user interaction
* Pass values between UI, process, and backend logic
* Support filtering and search functionality in background
Although invisible on the screen, Hidden fields are often **critical to correct data persistence and process behavior**.
***
### Adding and Configuring a Hidden Field
To add a Hidden field:
1. Drag a **Hidden** field into a Module layout
2. Click the **Edit (pencil) icon** on the field
3. The **Hidden Configuration** window opens
***
### Hidden Field Configuration Properties
The following table describes all available configuration properties for the Hidden field.
| Property | Mandatory | Description |
| --------------------- | --------- | --------------------------------------------------------------------------------------- |
| **MF ID** | Yes | System‑generated unique identifier |
| **Source Tag** | No | Allows custom JavaScript at field level (e.g. `readonly`, `onchange=validateNum(this)`) |
| **Default Value** | No | Default value assigned to the field |
| **Field\_ID** | No | Database column mapped to this field |
| **ShowFieldName** | Yes | Logical field name; auto‑generated when clicking the blue icon |
| **SearchCriteria** | No | Marks the field as a search criterion |
| **ShowSearch** | No | Displays this field in search result table |
| **SearchFromTo** | No | Enables range‑based search |
| **SearchPreLike** | No | Enables wildcard search (e.g. `%XXX`) |
| **SearchLike** | No | Enables wildcard search (e.g. `XXX%`) |
| **SearchIgnoreCase** | No | Enables case‑insensitive search |
| **JoinSearchTable** | No | Used when JOIN SQL is required for search |
| **SearchFieldGroup** | No | Horizontal position in search criteria |
| **SearchCriteriaSeq** | No | Vertical position in search criteria |
| **ShowSearchSeq** | No | Position in search results |
| **Alignment** | No | Text alignment: Left / Center / Right |
| **OnlyGuiFlag** | No | UI‑only field (not persisted to database) |
| **ViewFlag** | No | Displays field in view/read mode |
| **KeepHistory** | No | Persists value history in database |
| **FilterFlag** | No | Used in 1‑Many Modules for filtering records |
| **Authen** | No | Applies IAM‑based authorization |
| **MergeFlag** | No | Merges field across multiple columns |
| **Validate Code** | No | Validation logic (e.g. `CHECK_NULL`, `CHECK_INTEGER`, `CHECK_EMAIL_FORMAT`) |
***
### Validation Options (Validate Code)
The **Validate Code** property supports built‑in validation rules, such as:
* `CHECK_NULL` – Prevents saving when value is null
* `CHECK_INTEGER` – Ensures integer input
* `CHECK_DECIMAL` – Ensures decimal input
* `CHECK_EMAIL_FORMAT` – Validates email format
These validations are applied even though the field is hidden.
***
### Authorization (Authen)
When **Authen** is enabled:
* Hidden field behavior is controlled by ONEWEB’s IAM
* Useful for role‑based or conditional logic
* Common in workflows or secured entity designs
***
### Usage Guidelines
* Use Hidden fields for **technical or system values**
* Do not use Hidden fields for user input
* Always document the purpose of each Hidden field
* Use `OnlyGuiFlag` when the value should not be persisted
* Be cautious when using Hidden fields in Search or Filter logic
* Avoid excessive Hidden fields to reduce complexity
***
### Summary
The **Hidden** field is a non‑visual but fundamental component in ONEWEB Smart Forms.
Key points:
* Stores invisible system or contextual data
* Can be mapped to database columns or UI‑only logic
* Supports validation, search, and filtering
* Integrates with IAM authorization
* Essential for IDs, keys, and background processing
Correct use of Hidden fields ensures Smart Forms remain **robust, secure, and functionally complete**, even when complex backend logic is required.
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