Add support for scanning columns (#5)

Reviewed-on: #5

errors.go

@@ -3,3 +3,5 @@ package mysqlite
 import "errors"
 
 var ErrNoRows = errors.New("mysqlite: no rows returned")
+var ErrMissingBind = errors.New("mysqlite: missing bind value")
+var ErrMissingScan = errors.New("mysqlite: missing scan value")

query.go

@@ -11,8 +11,10 @@ type Query struct {
 	stmt *sqlite.Stmt
 	// Reference to the database. If set, it is assumed that a lock was taken
 	// by the query that should be freed by the query.
-	db  *Db
-	err error
+	db *Db
+	// The number of bound arguments
+	binds int
+	err   error
 }
 
 func (d *Db) Query(query string) *Query {
@@ -46,20 +48,33 @@ func (q *Query) bindInto(into *int, args ...any) *Query {
 		*into++
 		if arg == nil {
 			q.stmt.BindNull(*into)
+			q.binds++
 			continue
 		}
 		v := reflect.ValueOf(arg)
 		if v.Kind() == reflect.Ptr {
+			if v.IsNil() {
+				q.stmt.BindNull(*into)
+				q.binds++
+				continue
+			}
 			arg = v.Elem().Interface()
 		}
 		if asString, ok := arg.(string); ok {
 			q.stmt.BindText(*into, asString)
+			q.binds++
 		} else if asInt, ok := arg.(int); ok {
 			q.stmt.BindInt64(*into, int64(asInt))
-		} else if asInt, ok := arg.(int64); ok {
-			q.stmt.BindInt64(*into, asInt)
+			q.binds++
+		} else if asInt64, ok := arg.(int64); ok {
+			q.stmt.BindInt64(*into, asInt64)
+			q.binds++
+		} else if asFloat, ok := arg.(float64); ok {
+			q.stmt.BindFloat(*into, asFloat)
+			q.binds++
 		} else if asBool, ok := arg.(bool); ok {
 			q.stmt.BindBool(*into, asBool)
+			q.binds++
 		} else {
 			// Check if the argument is a slice or array of any type
 			v = reflect.ValueOf(arg)
@@ -104,6 +119,23 @@ func (q *Query) MustExec() {
 	}
 }
 
+func (q *Query) ScanColumns(results *[]string) *Query {
+	if q.err != nil {
+		return q
+	}
+
+	// Ensure the number of results matches the number of columns
+	if q.stmt.ColumnCount() != len(*results) {
+		*results = make([]string, q.stmt.ColumnCount())
+	}
+
+	// Fetch the column names
+	for i := 0; i < q.stmt.ColumnCount(); i++ {
+		(*results)[i] = q.stmt.ColumnName(i)
+	}
+	return q
+}
+
 func (q *Query) ScanSingle(results ...any) (rerr error) {
 	defer q.unlock()
 	// Scan rows
@@ -162,6 +194,10 @@ type Rows struct {
 }
 
 func (q *Query) ScanMulti() (*Rows, error) {
+	if q.binds != q.stmt.BindParamCount() {
+		return nil, ErrMissingBind
+	}
+
 	if q.err != nil {
 		return nil, q.err
 	}
@@ -199,6 +235,9 @@ func (r *Rows) MustNext() bool {
 }
 
 func (r *Rows) Scan(results ...any) error {
+	if r.query.stmt.ColumnCount() != len(results) {
+		return ErrMissingScan
+	}
 	for i, arg := range results {
 		err := r.scanArgument(i, arg)
 		if err != nil {
@@ -213,6 +252,10 @@ func (r *Rows) scanArgument(i int, arg any) error {
 		*asString = r.query.stmt.ColumnText(i)
 	} else if asInt, ok := arg.(*int); ok {
 		*asInt = r.query.stmt.ColumnInt(i)
+	} else if asInt, ok := arg.(*int64); ok {
+		*asInt = r.query.stmt.ColumnInt64(i)
+	} else if asFloat, ok := arg.(*float64); ok {
+		*asFloat = r.query.stmt.ColumnFloat(i)
 	} else if asBool, ok := arg.(*bool); ok {
 		*asBool = r.query.stmt.ColumnBool(i)
 	} else if reflect.TypeOf(arg).Kind() == reflect.Ptr && reflect.TypeOf(arg).Elem().Kind() == reflect.Ptr {

query_test.go

@@ -28,6 +28,36 @@ func TestSimpleQueryWithNoResults(t *testing.T) {
 	require.True(t, errors.Is(err, ErrNoRows))
 }
 
+func TestScanWithMissingValues(t *testing.T) {
+	db := openTestDb(t)
+	var count int
+	err := db.Query("select 1, 2").ScanSingle(&count)
+	require.Equal(t, ErrMissingScan, err)
+}
+
+func TestScanColumns(t *testing.T) {
+	db := openTestDb(t)
+	var columns []string
+	var key string
+	err := db.Query("select `key` from mytable").
+		ScanColumns(&columns).
+		ScanSingle(&key)
+	require.NoError(t, err, "expected no error scanning columns")
+	require.Equal(t, 1, len(columns), "expected one column")
+	require.Equal(t, "key", columns[0], "expected column name 'key'")
+	require.Equal(t, "foo", key, "expected key to be 'foo'")
+}
+
+func TestBindInt64(t *testing.T) {
+	db := openTestDb(t)
+	var value int64
+	var result int64
+	value = 5
+	err := db.Query("select ?").Bind(&value).ScanSingle(&result)
+	require.NoError(t, err)
+	require.Equal(t, int64(5), result)
+}
+
 func TestSimpleQueryWithArgs(t *testing.T) {
 	db := openTestDb(t)
 	var value string
@@ -122,6 +152,26 @@ func TestUpdateQueryWithPointerValue(t *testing.T) {
 	require.Equal(t, "ipsum", value)
 }
 
+func TestUpdateQueryWithSetPointerValue(t *testing.T) {
+	type S struct {
+		value *string
+	}
+	db := openTestDb(t)
+	func() {
+		tx := db.MustBegin()
+		defer tx.MustRollback()
+		tx.Query("insert into mytable(key, value) values ('lorem', 'bar')").MustExec()
+		s := S{nil}
+		key := "lorem"
+		tx.Query("update mytable set value = ? where key = ?").Bind(s.value, key).MustExec()
+		tx.MustCommit()
+	}()
+
+	var value *string
+	db.Query("select value from mytable where key = 'lorem'").MustScanSingle(&value)
+	require.Equal(t, (*string)(nil), value)
+}
+
 func TestUpdateQueryWithNullValue(t *testing.T) {
 	db := openTestDb(t)
 	func() {
@@ -147,6 +197,31 @@ func TestQueryWithPointerStringArguments(t *testing.T) {
 	require.Equal(t, "bar", *result)
 }
 
+func TestQueryWithInt64Scan(t *testing.T) {
+	db := openTestDb(t)
+	var result int64
+	err := db.Query("select 2").ScanSingle(&result)
+	require.NoError(t, err)
+	require.NotNil(t, result)
+	require.Equal(t, int64(2), result)
+}
+
+func TestQueryWithFloat64Scan(t *testing.T) {
+	db := openTestDb(t)
+	var result float64
+	err := db.Query("select 2.5").ScanSingle(&result)
+	require.NoError(t, err)
+	require.NotNil(t, result)
+	require.InDelta(t, 2.5, result, 0.001)
+}
+
+func TestQueryWithMissingBinds(t *testing.T) {
+	db := openTestDb(t)
+	var result float64
+	err := db.Query("select ?").ScanSingle(&result)
+	require.ErrorIs(t, err, ErrMissingBind)
+}
+
 func TestQueryWithPointerStringArgumentsCanSetToNull(t *testing.T) {
 	db := openTestDb(t)
 	db.Query("update mytable set value=null where key = 'foo'").MustExec()