Use returned ID from INSERT in create filter (#297)

src/github.com/matrix-org/dendrite/clientapi/auth/storage/accounts/filter_table.go

@@ -15,8 +15,8 @@
 package accounts
 
 import (
-	"database/sql"
 	"context"
+	"database/sql"
 )
 
 const filterSchema = `
@@ -41,13 +41,9 @@ const selectFilterSQL = "" +
 const insertFilterSQL = "" +
 	"INSERT INTO account_filter (filter, id, localpart) VALUES ($1, DEFAULT, $2) RETURNING id"
 
-const findMaxIDSQL = "" +
-	"SELECT MAX(id) FROM account_filter WHERE localpart = $1"
-
 type filterStatements struct {
 	selectFilterStmt *sql.Stmt
 	insertFilterStmt *sql.Stmt
-	findMaxIDStmt	 *sql.Stmt
 }
 
 func (s *filterStatements) prepare(db *sql.DB) (err error) {
@@ -61,10 +57,6 @@ func (s *filterStatements) prepare(db *sql.DB) (err error) {
 	if s.insertFilterStmt, err = db.Prepare(insertFilterSQL); err != nil {
 		return
 	}
-	if s.findMaxIDStmt, err = db.Prepare(findMaxIDSQL); err != nil {
-		return
-	}
-
 	return
 }
 
@@ -77,14 +69,7 @@ func (s *filterStatements) selectFilter(
 
 func (s *filterStatements) insertFilter(
 	ctx context.Context, filter string, localpart string,
-) (err error) {
-	_, err = s.insertFilterStmt.ExecContext(ctx, filter, localpart)
-	return
-}
-
-func (s *filterStatements) findMaxID(
-	ctx context.Context, localpart string,
-) (id string, err error) {
-	err = s.findMaxIDStmt.QueryRowContext(ctx, localpart).Scan(&id)
+) (pos string, err error) {
+	err = s.insertFilterStmt.QueryRowContext(ctx, filter, localpart).Scan(&pos)
 	return
 }

src/github.com/matrix-org/dendrite/clientapi/auth/storage/accounts/storage.go

@@ -333,11 +333,7 @@ func (d *Database) GetFilter(
 func (d *Database) PutFilter(
 	ctx context.Context, localpart, filter string,
 ) (string, error) {
-	err := d.filter.insertFilter(ctx, filter, localpart)
-	if err != nil {
-		return "", err
-	}
-	return d.filter.findMaxID(ctx, localpart)
+	return d.filter.insertFilter(ctx, filter, localpart)
 }
 
 // CheckAccountAvailability checks if the username/localpart is already present in the database.