feat: ExecOptions.ExpectResults

sqlitex/exec.go

@@ -63,6 +63,9 @@ type ExecOptions struct {
 	// If ResultFunc returns an error then iteration ceases
 	// and the execution function returns the error value.
 	ResultFunc func(stmt *sqlite.Stmt) error
+
+	// ExpectRows, if enabled,  will cause Execute calls to return [ErrNoRows] if the statement returns no rows.
+	ExpectRows bool
 }
 
 // Exec executes an SQLite query.
@@ -289,6 +292,7 @@ func exec(stmt *sqlite.Stmt, flags uint8, opts *ExecOptions) (err error) {
 		}
 		return fmt.Errorf("sqlitex.Exec: missing argument for %s", name)
 	}
+	hasResults := false
 	for {
 		hasRow, err := stmt.Step()
 		if err != nil {
@@ -297,12 +301,16 @@ func exec(stmt *sqlite.Stmt, flags uint8, opts *ExecOptions) (err error) {
 		if !hasRow {
 			break
 		}
+		hasResults = true
 		if opts != nil && opts.ResultFunc != nil {
 			if err := opts.ResultFunc(stmt); err != nil {
 				return err
 			}
 		}
 	}
+	if opts != nil && opts.ExpectRows && !hasResults {
+		return ErrNoResults
+	}
 	return nil
 }
 

sqlitex/exec_test.go

@@ -18,6 +18,7 @@
 package sqlitex
 
 import (
+	"errors"
 	"fmt"
 	"reflect"
 	"testing"
@@ -296,6 +297,59 @@ INSERT INTO t (a, b) VALUES ('a2', :a2);
 	})
 }
 
+func TestExecuteExpectResults(t *testing.T) {
+	conn, err := sqlite.OpenConn(":memory:", 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer conn.Close()
+
+	script := `
+CREATE TABLE t (a TEXT, b INTEGER);
+INSERT INTO t (a, b) VALUES ('a1', 1);
+`
+	err = ExecuteScript(conn, script, &ExecOptions{})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	args := map[string]any{
+		":a": "a2",
+	}
+
+	var bVal int
+
+	err = Execute(conn, `SELECT b FROM t WHERE a==:a`, &ExecOptions{
+		Named: args,
+		ResultFunc: func(stmt *sqlite.Stmt) error {
+			bVal = stmt.ColumnInt(0)
+			return nil
+		},
+		ExpectRows: false,
+	})
+	if err != nil {
+		t.Errorf("err=%v, want nil", err)
+	}
+	if bVal != 0 {
+		t.Errorf("bVal=%d, want 0 - ResultFunc should not have run", bVal)
+	}
+
+	err = Execute(conn, `SELECT b FROM t WHERE a==:a`, &ExecOptions{
+		Named: args,
+		ResultFunc: func(stmt *sqlite.Stmt) error {
+			bVal = stmt.ColumnInt(0)
+			return nil
+		},
+		ExpectRows: true,
+	})
+	if !errors.Is(err, ErrNoResults) {
+		t.Errorf("err=%v, want ErrNoResults", err)
+	}
+	if bVal != 0 {
+		t.Errorf("bVal=%d, want 0 - ResultFunc should not have run", bVal)
+	}
+}
+
 func TestBitsetHasAll(t *testing.T) {
 	tests := []struct {
 		bs   bitset

sqlitex/query.go

@@ -9,8 +9,10 @@ import (
 	"zombiezen.com/go/sqlite"
 )
 
-var errNoResults = errors.New("sqlite: statement has no results")
-var errMultipleResults = errors.New("sqlite: statement has multiple result rows")
+var (
+	ErrNoResults       = errors.New("sqlite: statement has no results")
+	ErrMultipleResults = errors.New("sqlite: statement has multiple result rows")
+)
 
 func resultSetup(stmt *sqlite.Stmt) error {
 	hasRow, err := stmt.Step()
@@ -20,7 +22,7 @@ func resultSetup(stmt *sqlite.Stmt) error {
 	}
 	if !hasRow {
 		stmt.Reset()
-		return errNoResults
+		return ErrNoResults
 	}
 	return nil
 }
@@ -33,7 +35,7 @@ func resultTeardown(stmt *sqlite.Stmt) error {
 	}
 	if hasRow {
 		stmt.Reset()
-		return errMultipleResults
+		return ErrMultipleResults
 	}
 	return stmt.Reset()
 }