app: upcast loadedDatabase to more specific interfaces

db_badger.go

@@ -83,10 +83,6 @@ func (ld *badgerLoadedDatabase) RenderForNav(f *TMainForm, ndata *navData) error
 	return nil
 }
 
-func (n *badgerLoadedDatabase) ApplyChanges(f *TMainForm, ndata *navData) error {
-	return ErrNotSupported
-}
-
 func (ld *badgerLoadedDatabase) NavChildren(ndata *navData) ([]string, error) {
 	// In the Badger implementation, there is only one child: "Data"
 	if len(ndata.bucketPath) == 0 {
@@ -102,10 +98,6 @@ func (ld *badgerLoadedDatabase) NavContext(ndata *navData) ([]contextAction, err
 	return nil, nil // No special actions are supported
 }
 
-func (ld *badgerLoadedDatabase) ExecQuery(query string, resultArea *vcl.TStringGrid) error {
-	return ErrNotSupported
-}
-
 func (ld *badgerLoadedDatabase) Close() {
 	_ = ld.db.Close()
 	ld.arena = nil

db_bolt.go

@@ -192,10 +192,6 @@ func (ld *boltLoadedDatabase) DeleteBucket(sender vcl.IComponent, ndata *navData
 	return nil
 }
 
-func (ld *boltLoadedDatabase) ExecQuery(query string, resultArea *vcl.TStringGrid) error {
-	return ErrNotSupported
-}
-
 func (ld *boltLoadedDatabase) Close() {
 	_ = ld.db.Close()
 	ld.arena = nil

db_debconf.go

@@ -70,10 +70,6 @@ func (ld *debconfLoadedDatabase) RenderForNav(f *TMainForm, ndata *navData) erro
 	return nil
 }
 
-func (n *debconfLoadedDatabase) ApplyChanges(f *TMainForm, ndata *navData) error {
-	return ErrNotSupported
-}
-
 func (ld *debconfLoadedDatabase) NavChildren(ndata *navData) ([]string, error) {
 	// In the debconf implementation, there is only one child: "Data"
 	if len(ndata.bucketPath) == 0 {
@@ -89,10 +85,6 @@ func (ld *debconfLoadedDatabase) NavContext(ndata *navData) ([]contextAction, er
 	return nil, nil // No special actions are supported
 }
 
-func (ld *debconfLoadedDatabase) ExecQuery(query string, resultArea *vcl.TStringGrid) error {
-	return ErrNotSupported
-}
-
 func (ld *debconfLoadedDatabase) Close() {
 	ld.arena = nil
 }

db_none.go

@@ -23,14 +23,6 @@ func (n *noLoadedDatabase) RenderForNav(f *TMainForm, ndata *navData) error {
 	return nil
 }
 
-func (n *noLoadedDatabase) ApplyChanges(f *TMainForm, ndata *navData) error {
-	return ErrNotSupported
-}
-
-func (n *noLoadedDatabase) ExecQuery(query string, resultArea *vcl.TStringGrid) error {
-	return ErrNotSupported
-}
-
 func (n *noLoadedDatabase) NavChildren(ndata *navData) ([]string, error) {
 	return []string{}, nil
 }

db_pebble.go

@@ -74,10 +74,6 @@ func (ld *pebbleLoadedDatabase) RenderForNav(f *TMainForm, ndata *navData) error
 	return nil
 }
 
-func (n *pebbleLoadedDatabase) ApplyChanges(f *TMainForm, ndata *navData) error {
-	return ErrNotSupported
-}
-
 func (ld *pebbleLoadedDatabase) NavChildren(ndata *navData) ([]string, error) {
 	// In the pebble implementation, there is only one child: "Data"
 	if len(ndata.bucketPath) == 0 {
@@ -93,10 +89,6 @@ func (ld *pebbleLoadedDatabase) NavContext(ndata *navData) ([]contextAction, err
 	return nil, nil // No special actions are supported
 }
 
-func (ld *pebbleLoadedDatabase) ExecQuery(query string, resultArea *vcl.TStringGrid) error {
-	return ErrNotSupported
-}
-
 func (ld *pebbleLoadedDatabase) Close() {
 	_ = ld.db.Close()
 	ld.arena = nil

db_redis.go

@@ -132,10 +132,6 @@ func (ld *redisLoadedDatabase) RenderForNav(f *TMainForm, ndata *navData) error
 	}
 }
 
-func (n *redisLoadedDatabase) ApplyChanges(f *TMainForm, ndata *navData) error {
-	return ErrNotSupported
-}
-
 func (ld *redisLoadedDatabase) NavChildren(ndata *navData) ([]string, error) {
 	// ctx := context.Background()
 

db_sqlite.go

@@ -100,10 +100,6 @@ func (ld *sqliteLoadedDatabase) RenderForNav(f *TMainForm, ndata *navData) error
 
 }
 
-func (n *sqliteLoadedDatabase) ApplyChanges(f *TMainForm, ndata *navData) error {
-	return ErrNotSupported
-}
-
 func (ld *sqliteLoadedDatabase) sqliteGetColumnNamesForTable(tableName string) ([]string, error) {
 	colr, err := ld.db.Query(`SELECT name FROM pragma_table_info( ? )`, tableName)
 	if err != nil {

loadedDatabase.go

@@ -7,7 +7,6 @@ import (
 )
 
 var ErrNavNotExist error = errors.New("The selected item no longer exists")
-var ErrNotSupported error = errors.New("Unsupported action for this database type")
 
 type contextAction struct {
 	Name     string
@@ -20,14 +19,20 @@ type loadedDatabase interface {
 	DriverName() string
 	RootElement() *vcl.TTreeNode
 	RenderForNav(f *TMainForm, ndata *navData) error
-	ApplyChanges(f *TMainForm, ndata *navData) error
-	ExecQuery(query string, resultArea *vcl.TStringGrid) error
 	NavChildren(ndata *navData) ([]string, error)
 	NavContext(ndata *navData) ([]contextAction, error)
 	Keepalive(ndata *navData)
 	Close()
 }
 
+type queryableLoadedDatabase interface {
+	ExecQuery(query string, resultArea *vcl.TStringGrid) error
+}
+
+type editableLoadedDatabase interface {
+	ApplyChanges(f *TMainForm, ndata *navData) error
+}
+
 // navData is the .Data() pointer for each TTreeNode in the left-hand tree.
 type navData struct {
 	ld             loadedDatabase

main.go

@@ -668,7 +668,14 @@ func (f *TMainForm) OnDataCommitClick(sender vcl.IObject) {
 	scrollPos := f.contentBox.TopRow()
 
 	ndata := (*navData)(node.Data())
-	err := ndata.ld.ApplyChanges(f, ndata)
+
+	editableLd, ok := ndata.ld.(editableLoadedDatabase)
+	if !ok {
+		vcl.ShowMessage("Unsupported action for this database")
+		return
+	}
+
+	err := editableLd.ApplyChanges(f, ndata)
 	if err != nil {
 		vcl.ShowMessage(err.Error())
 	}
@@ -757,7 +764,14 @@ func (f *TMainForm) OnQueryExecute(sender vcl.IObject) {
 	}
 
 	ndata := (*navData)(node.Data())
-	err := ndata.ld.ExecQuery(queryString, f.queryResult)
+
+	queryableLd, ok := ndata.ld.(queryableLoadedDatabase)
+	if !ok {
+		vcl.ShowMessage("Unsupported action for this database")
+		return
+	}
+
+	err := queryableLd.ExecQuery(queryString, f.queryResult)
 	if err != nil {
 		vcl.ShowMessage(err.Error())
 		return