parser: Return error if missing RETURNING

If a query specifies a return value (:one or :many), require that statements have a RETURNING clause. Fixes #121

internal/dinosql/parser.go

@@ -339,6 +339,30 @@ func parseMetadata(t string) (string, string, error) {
 return "", "", nil
 }
 
+func validateCmd(n nodes.Node, name, cmd string) error {
+// TODO: Convert cmd to an enum
+if !(cmd == ":many" || cmd == ":one") {
+return nil
+}
+var list nodes.List
+switch stmt := n.(type) {
+case nodes.SelectStmt:
+return nil
+case nodes.DeleteStmt:
+list = stmt.ReturningList
+case nodes.InsertStmt:
+list = stmt.ReturningList
+case nodes.UpdateStmt:
+list = stmt.ReturningList
+default:
+return nil
+}
+if len(list.Items) == 0 {
+return fmt.Errorf("query %q specifies parameter %q without containing a RETURNING clause", name, cmd)
+}
+return nil
+}
+
 func parseQuery(c core.Catalog, stmt nodes.Node, source string) (*Query, error) {
 if err := validateParamRef(stmt); err != nil {
 return nil, err
@@ -366,7 +390,9 @@ func parseQuery(c core.Catalog, stmt nodes.Node, source string) (*Query, error)
 if err != nil {
 return nil, err
 }
-
+if err := validateCmd(raw.Stmt, name, cmd); err != nil {
+return nil, err
+}
 rvs := rangeVars(raw.Stmt)
 refs := findParameters(raw.Stmt)
 params, err := resolveCatalogRefs(c, rvs, refs)

internal/dinosql/query_test.go

@@ -807,6 +807,13 @@ func TestInvalidQueries(t *testing.T) {
 SELECT id FROM foo;
 `,
 },
+{
+`
+CREATE TABLE foo (id text not null);
+-- name: DeleteFoo :one
+DELETE FROM foo WHERE id = $1;
+`,
+},
 } {
 test := tc
 t.Run(strconv.Itoa(i), func(t *testing.T) {