Separate exec types into files, document code (#10)

Reviewed-on: #10

exec/delete.go

@@ -0,0 +1,90 @@
+package exec
+
+import (
+	"database/sql"
+	"errors"
+	"reflect"
+
+	"git.gdulai.com/gdulai/simpleorm"
+	"git.gdulai.com/gdulai/simpleorm/schema"
+	log "gitlab.com/gdulai/simpleloglvl"
+)
+
+// Delete represents a delete operation.
+type Delete[T any] struct {
+	target   schema.Table // The table from which records will be deleted.
+	toDelete []T          // A slice of model instances to be deleted.
+}
+
+// NewDelete creates a new instance of Delete.
+//
+// Parameters:
+// - orm: The ORM instance that manages the database connection and schema
+// - toDelete: A slice of model instances to delete
+//
+// Returns:
+// - Delete[T]: A new Delete operation instance
+// - error: An error if the table could not be found in the schema cache
+func NewDelete[T any](orm *simpleorm.ORM, toDelete []T) (Delete[T], error) {
+	table, ok := orm.Cache().Get(reflect.TypeFor[T]().Name())
+	if !ok {
+		return Delete[T]{}, errors.New("Failed to get table from schema cache")
+	}
+
+	return Delete[T]{target: *table, toDelete: toDelete}, nil
+}
+
+// Execute executes the delete operation.
+func (d *Delete[T]) Execute(conn *simpleorm.DBConnection) error {
+	return d.execute(conn, nil)
+}
+
+// execute constructs and executes the DELETE SQL statement.
+//
+// Parameters:
+// - conn: The database connection to use for executing the query
+// - tx: Optional transaction to use instead of a connection
+//
+// Returns:
+// - error: An error if the operation fails
+func (d *Delete[T]) execute(conn *simpleorm.DBConnection, tx *sql.Tx) error {
+	count := len(d.toDelete)
+	dml, err := d.target.GetDeleteDML(count)
+	if err != nil {
+		return err
+	}
+
+	var params []any
+
+	for _, del := range d.toDelete {
+		pkCols, err := getPk(del, d.target)
+		if err != nil {
+			return err
+		}
+
+		for _, pk := range pkCols {
+			params = append(params, pk)
+		}
+	}
+
+	log.LogDebug("%s [%s]", dml, params)
+
+	var stmt *sql.Stmt
+	if tx != nil {
+		stmt, err = tx.Prepare(dml)
+	} else {
+		stmt, err = conn.Prepare(dml)
+	}
+	defer stmt.Close()
+
+	result, err := stmt.Exec(params...)
+	if err != nil {
+		return err
+	} else {
+		rowsAffected, _ := result.RowsAffected()
+		log.LogInfo("Deleted %s row", rowsAffected)
+	}
+
+	return nil
+
+}