# gormcol

Type-safe GORM column descriptors and model generation utilities.

## Library

The `gormcol` package provides two approaches for referencing database columns:

### Field descriptors

Define struct-like variables mapping Go field names to `table.column` pairs:

```go
var PsAccess = struct {
    IDProfile           gormcol.Field
    IDAuthorizationRole gormcol.Field
}{
    IDProfile:           gormcol.Field{Table: "ps_access", Column: "id_profile"},
    IDAuthorizationRole: gormcol.Field{Table: "ps_access", Column: "id_authorization_role"},
}
```

```go
gormcol.Column(PsAccess.IDAuthorizationRole)     // "id_authorization_role"
gormcol.ColumnOnTable(PsAccess.IDAuthorizationRole) // "ps_access.id_authorization_role"
gormcol.TableField(PsAccess.IDAuthorizationRole)  // "ps_access"
```

### Reflection-based utilities

Extract column/table names from GORM struct tags at compile time:

```go
type PsAccess struct {
    IDProfile           uint `gorm:"column:id_profile;primaryKey"`
    IDAuthorizationRole uint `gorm:"column:id_authorization_role"`
}

gormcol.Col[PsAccess]("IDAuthorizationRole")       // "id_authorization_role"
gormcol.Tbl[PsAccess]()                             // "ps_access" (via NamingStrategy)
gormcol.ColOnTbl[PsAccess]("IDAuthorizationRole")  // "ps_access.id_authorization_role"
gormcol.PK[PsAccess]()                              // "id_profile"
gormcol.Columns[PsAccess]()                         // ["id_profile", "id_authorization_role"]
gormcol.ColByJSON[PsAccess]("id_profile")           // "id_profile"
```

### Naming strategy

The reflection-based functions fall back to a configurable `NamingStrategy` when no explicit `gorm:"column:..."` tag is set. Default is `schema.NamingStrategy{}`. Override it with your project's GORM naming strategy:

```go
gormcol.NamingStrategy = db.DB.NamingStrategy
```

## CLI

The `cmd/` directory contains a standalone tool that generates GORM model files with column descriptors.

### Build

```bash
go build -o gormcol-gen ./cmd/
```

### Usage

```
gormcol-gen --dsn <connection-string> [options]
```

| Flag | Default | Description |
|------|---------|-------------|
| `--dsn` | *(required)* | MySQL/MariaDB DSN, e.g. `user:pass@tcp(localhost:3306)/dbname` |
| `--filter` | `(ps_\|b2b_).*` | Regex matching table names to generate |
| `--out` | `./app/model/prestadb` | Output directory for generated files |
| `--pkg` | `prestadb` | Go package name for generated files |

### Example

```bash
./gormcol-gen --dsn "user:pass@tcp(localhost:3306)/mydb" --filter "ps_.*" --out ./internal/model --pkg model
```

This connects to the database, generates a `.go` model file for each matching table, and appends `<Model>Cols` variables with typed `gormcol.Field` descriptors to each file.

## Dependencies

- `gorm.io/gorm`
- `gorm.io/gen`
- `gorm.io/driver/mysql`