# gormcol

Type-safe GORM column descriptors and model generation utilities.

## Library

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"},
}
```

Use the three accessor functions to extract column and table names without string literals:

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

## CLI

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

### Install

```bash
go install git.ma-al.com/goc_marek/gormcol/cmd@latest
```

### 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.

## Using generated models

After generation, each model file contains a struct and a `Cols` variable:

```go
// model/product.go
type Product struct {
    ID    uint   `gorm:"column:id_product;primaryKey"`
    Name  string `gorm:"column:name"`
    Price float32 `gorm:"column:price;type:decimal(20,6)"`
}

var ProductCols = struct {
    ID    Field
    Name  Field
    Price Field
}{
    ID:    Field{Table: "ps_product", Column: "id_product"},
    Name:  Field{Table: "ps_product", Column: "name"},
    Price: Field{Table: "ps_product", Column: "price"},
}
```

### GORM queries with type-safe columns

Use `ColumnOnTable` for table-qualified column references in GORM clauses:

```go
import "git.ma-al.com/goc_marek/gormcol"

// Where clauses
db.Where(
    gormcol.ColumnOnTable(model.ProductCols.Price) + " > ?",
    100.0,
).Find(&products)

// Order
db.Order(gormcol.ColumnOnTable(model.ProductCols.Name) + " ASC").Find(&products)

// Joins
db.Joins("JOIN ps_category ON " +
    gormcol.ColumnOnTable(model.ProductCols.ID) + " = ps_category.id_product",
).Find(&products)
```

### Unqualified column names

Use `Column` when the table is already scoped:

```go
db.Select(gormcol.Column(model.ProductCols.Name)).Find(&products)

// Raw queries
db.Raw("SELECT " + gormcol.Column(model.ProductCols.Name) + " FROM ps_product").Scan(&names)
```

### Table name

Use `TableField` to get the table name from a column descriptor:

```go
table := gormcol.TableField(model.ProductCols.ID) // "ps_product"
```

## Dependencies

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