# (DD05) Business Logic — BusinessLabel.toString() [5 LOC]

| Field | Value |
|-------|-------|
| Fully Qualified Name | `com.optage.model.BusinessLabel` |
| Layer | Utility / Model |
| Module | `model` (Package: `com.optage.model`) |

## 1. Role

### BusinessLabel.toString()

This method provides a standardized textual representation of a `BusinessLabel` domain object for diagnostics, logging, and human-readable inspection. It does not transform business data or execute workflow logic; instead, it consolidates the three core attributes of the object — field name, Japanese label, and source — into a single structured string. The method implements a simple formatting pattern that acts like a presentation adapter for the model, ensuring that any consumer sees the same canonical output shape. In the larger system, this is useful when objects are written to logs, debugger views, or test assertions, because the representation is stable and easy to scan. There are no branches, service delegations, or external dependencies in this method, so its role is purely local and deterministic.

## 2. Processing Pattern (Detailed Business Logic)

```mermaid
flowchart TD
    START(["toString()"])
    BUILD(["Format string using fieldName, label, source"])
    RETURN_NODE(["Return formatted BusinessLabel string"])
    START --> BUILD
    BUILD --> RETURN_NODE
```

## 3. Parameter Analysis

| No | Parameter Name | Type | Business Description |
|----|---------------|------|---------------------|
| - | (none) | - | The method accepts no parameters. It uses the instance fields `fieldName`, `label`, and `source` to build the display string. |

Instance fields read by the method:
- `fieldName` — internal field identifier used in the formatted output.
- `label` — Japanese label text shown in the formatted output.
- `source` — comment source or origin tag included in the formatted output.

## 4. CRUD Operations / Called Services

This method does not call any other business, service, or persistence methods. It performs no CRUD operation against a database or external system. The only operation is local string formatting via `String.format(...)`, which is a pure presentation step.

| CRUD | SC / CBS | SC Code | Entity / DB | Operation Description |
|------|----------|---------|-------------|----------------------|
| - | `String.format` | - | - | Builds a display string from the current object state; no persistence activity. |

## 5. Dependency Trace

The repository search for `toString(` found no application callers within `src/main/java` for `BusinessLabel.toString()`. The method is therefore treated as an internal utility invoked implicitly by Java tooling, logging frameworks, debuggers, or test code rather than by explicit business flow code in the current source tree.

| # | Caller (Screen/Batch) | Call Chain (Full Path to this Method) | Terminal (SC / CRUD / Entity) |
|---|----------------------|--------------------------------------|-------------------------------|
| 1 | Not found in `src/main/java` | `implicit Java object rendering` -> `BusinessLabel.toString()` | `String.format [R/O] N/A` |

## 6. Per-Branch Detail Blocks

**Block 1** — [RETURN] `(unconditional)` (L26-L29)

> Build the canonical string representation of the model instance for display and diagnostics.

| # | Type | Code |
|---|------|------|
| 1 | EXEC | `String.format("BusinessLabel{field=%s, label=%s, source=%s}", fieldName, label, source);` |
| 2 | RETURN | `return String.format(...);` |

## 7. Glossary

| Term | Type | Business Meaning |
|------|------|------------------|
| `BusinessLabel` | Model / Domain object | A lightweight model representing a business label with its field name, display label, and source origin. |
| `fieldName` | Field | Internal field identifier used to reference the labeled attribute. |
| `label` | Field | Human-readable Japanese label text associated with the field. |
| `source` | Field | Origin or comment source for the label metadata. |
| `String.format` | Technical API | Java formatting utility used to build a predictable text representation. |
| `toString` | Technical method | Standard Java object rendering method used for logging, debugging, and inspection. |