db: add common errunsupported

db_badger.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"errors"
 	"fmt"
 	"path/filepath"
 	"unsafe"
@@ -85,7 +84,7 @@ func (ld *badgerLoadedDatabase) RenderForNav(f *TMainForm, ndata *navData) {
 }
 
 func (n *badgerLoadedDatabase) ApplyChanges(f *TMainForm, ndata *navData) error {
-	return errors.New("Editing is not supported")
+	return ErrNotSupported
 }
 
 func (ld *badgerLoadedDatabase) NavChildren(ndata *navData) ([]string, error) {
@@ -104,7 +103,7 @@ func (ld *badgerLoadedDatabase) NavContext(ndata *navData) ([]contextAction, err
 }
 
 func (ld *badgerLoadedDatabase) ExecQuery(query string, resultArea *vcl.TStringGrid) error {
-	return errors.New("Badger doesn't support querying")
+	return ErrNotSupported
 }
 
 func (ld *badgerLoadedDatabase) Close() {

db_bolt.go

@@ -186,7 +186,7 @@ func (ld *boltLoadedDatabase) DeleteBucket(ndata *navData) {
 }
 
 func (ld *boltLoadedDatabase) ExecQuery(query string, resultArea *vcl.TStringGrid) error {
-	return errors.New("Bolt doesn't support querying")
+	return ErrNotSupported
 }
 
 func (ld *boltLoadedDatabase) Close() {

db_debconf.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"errors"
 	"fmt"
 	"os"
 	"path/filepath"
@@ -71,7 +70,7 @@ func (ld *debconfLoadedDatabase) RenderForNav(f *TMainForm, ndata *navData) {
 }
 
 func (n *debconfLoadedDatabase) ApplyChanges(f *TMainForm, ndata *navData) error {
-	return errors.New("Editing is not supported")
+	return ErrNotSupported
 }
 
 func (ld *debconfLoadedDatabase) NavChildren(ndata *navData) ([]string, error) {
@@ -90,7 +89,7 @@ func (ld *debconfLoadedDatabase) NavContext(ndata *navData) ([]contextAction, er
 }
 
 func (ld *debconfLoadedDatabase) ExecQuery(query string, resultArea *vcl.TStringGrid) error {
-	return errors.New("debconf doesn't support querying")
+	return ErrNotSupported
 }
 
 func (ld *debconfLoadedDatabase) Close() {

db_none.go

@@ -1,8 +1,6 @@
 package main
 
 import (
-	"errors"
-
 	"github.com/ying32/govcl/vcl"
 )
 
@@ -25,11 +23,11 @@ func (n *noLoadedDatabase) RenderForNav(f *TMainForm, ndata *navData) {
 }
 
 func (n *noLoadedDatabase) ApplyChanges(f *TMainForm, ndata *navData) error {
-	return errors.New("Editing is not supported")
+	return ErrNotSupported
 }
 
 func (n *noLoadedDatabase) ExecQuery(query string, resultArea *vcl.TStringGrid) error {
-	return nil
+	return ErrNotSupported
 }
 
 func (n *noLoadedDatabase) NavChildren(ndata *navData) ([]string, error) {

db_pebble.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"context"
-	"errors"
 	"fmt"
 	"path/filepath"
 	"unsafe"
@@ -76,7 +75,7 @@ func (ld *pebbleLoadedDatabase) RenderForNav(f *TMainForm, ndata *navData) {
 }
 
 func (n *pebbleLoadedDatabase) ApplyChanges(f *TMainForm, ndata *navData) error {
-	return errors.New("Editing is not supported")
+	return ErrNotSupported
 }
 
 func (ld *pebbleLoadedDatabase) NavChildren(ndata *navData) ([]string, error) {
@@ -95,7 +94,7 @@ func (ld *pebbleLoadedDatabase) NavContext(ndata *navData) ([]contextAction, err
 }
 
 func (ld *pebbleLoadedDatabase) ExecQuery(query string, resultArea *vcl.TStringGrid) error {
-	return errors.New("pebble doesn't support querying")
+	return ErrNotSupported
 }
 
 func (ld *pebbleLoadedDatabase) Close() {

db_redis.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"context"
-	"errors"
 	"fmt"
 	"strconv"
 	"unsafe"
@@ -139,7 +138,7 @@ func (ld *redisLoadedDatabase) RenderForNav(f *TMainForm, ndata *navData) {
 }
 
 func (n *redisLoadedDatabase) ApplyChanges(f *TMainForm, ndata *navData) error {
-	return errors.New("Editing is not supported")
+	return ErrNotSupported
 }
 
 func (ld *redisLoadedDatabase) NavChildren(ndata *navData) ([]string, error) {

db_sqlite.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"database/sql"
-	"errors"
 	"fmt"
 	"path/filepath"
 	"unsafe"
@@ -98,7 +97,7 @@ func (ld *sqliteLoadedDatabase) RenderForNav(f *TMainForm, ndata *navData) {
 }
 
 func (n *sqliteLoadedDatabase) ApplyChanges(f *TMainForm, ndata *navData) error {
-	return errors.New("Editing is not supported")
+	return ErrNotSupported
 }
 
 func (ld *sqliteLoadedDatabase) sqliteGetColumnNamesForTable(tableName string) ([]string, error) {

loadedDatabase.go

@@ -7,6 +7,7 @@ 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