fork github.com/doug-martin

sqlgen/delete_sql_generator.go

@@ -0,0 +1,72 @@
+package sqlgen
+
+import (
+	"git.fsdpf.net/go/db/v2/exp"
+	"git.fsdpf.net/go/db/v2/internal/errors"
+	"git.fsdpf.net/go/db/v2/internal/sb"
+)
+
+type (
+	// An adapter interface to be used by a Dataset to generate SQL for a specific dialect.
+	// See DefaultAdapter for a concrete implementation and examples.
+	DeleteSQLGenerator interface {
+		Dialect() string
+		Generate(b sb.SQLBuilder, clauses exp.DeleteClauses)
+	}
+	// The default adapter. This class should be used when building a new adapter. When creating a new adapter you can
+	// either override methods, or more typically update default values.
+	// See (github.com/doug-martin/goqu/dialect/postgres)
+	deleteSQLGenerator struct {
+		CommonSQLGenerator
+	}
+)
+
+var ErrNoSourceForDelete = errors.New("no source found when generating delete sql")
+
+func NewDeleteSQLGenerator(dialect string, do *SQLDialectOptions) DeleteSQLGenerator {
+	return &deleteSQLGenerator{NewCommonSQLGenerator(dialect, do)}
+}
+
+func (dsg *deleteSQLGenerator) Generate(b sb.SQLBuilder, clauses exp.DeleteClauses) {
+	if !clauses.HasFrom() {
+		b.SetError(ErrNoSourceForDelete)
+		return
+	}
+	for _, f := range dsg.DialectOptions().DeleteSQLOrder {
+		if b.Error() != nil {
+			return
+		}
+		switch f {
+		case CommonTableSQLFragment:
+			dsg.ExpressionSQLGenerator().Generate(b, clauses.CommonTables())
+		case DeleteBeginSQLFragment:
+			dsg.DeleteBeginSQL(
+				b, exp.NewColumnListExpression(clauses.From()), !(clauses.HasLimit() || clauses.HasOrder()),
+			)
+		case FromSQLFragment:
+			dsg.FromSQL(b, exp.NewColumnListExpression(clauses.From()))
+		case WhereSQLFragment:
+			dsg.WhereSQL(b, clauses.Where())
+		case OrderSQLFragment:
+			if dsg.DialectOptions().SupportsOrderByOnDelete {
+				dsg.OrderSQL(b, clauses.Order())
+			}
+		case LimitSQLFragment:
+			if dsg.DialectOptions().SupportsLimitOnDelete {
+				dsg.LimitSQL(b, clauses.Limit())
+			}
+		case ReturningSQLFragment:
+			dsg.ReturningSQL(b, clauses.Returning())
+		default:
+			b.SetError(ErrNotSupportedFragment("DELETE", f))
+		}
+	}
+}
+
+// Adds the correct fragment to being an DELETE statement
+func (dsg *deleteSQLGenerator) DeleteBeginSQL(b sb.SQLBuilder, from exp.ColumnListExpression, multiTable bool) {
+	b.Write(dsg.DialectOptions().DeleteClause)
+	if multiTable && dsg.DialectOptions().SupportsDeleteTableHint {
+		dsg.SourcesSQL(b, from)
+	}
+}