GoToSocial/internal/db/bundb/upsert.go

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// GoToSocial
// Copyright (C) GoToSocial Authors admin@gotosocial.org
// SPDX-License-Identifier: AGPL-3.0-or-later
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package bundb
import (
"context"
"database/sql"
"reflect"
"strings"
"github.com/superseriousbusiness/gotosocial/internal/gtserror"
"github.com/uptrace/bun"
"github.com/uptrace/bun/dialect"
)
// UpsertQuery is a wrapper around an insert query that can update if an insert fails.
// Doesn't implement the full set of Bun query methods, but we can add more if we need them.
// See https://bun.uptrace.dev/guide/query-insert.html#upsert
type UpsertQuery struct {
db bun.IDB
model interface{}
constraints []string
columns []string
}
func NewUpsert(idb bun.IDB) *UpsertQuery {
// note: passing in rawtx as conn iface so no double query-hook
// firing when passed through the bun.Tx.Query___() functions.
return &UpsertQuery{db: idb}
}
// Model sets the model or models to upsert.
func (u *UpsertQuery) Model(model interface{}) *UpsertQuery {
u.model = model
return u
}
// Constraint sets the columns or indexes that are used to check for conflicts.
// This is required.
func (u *UpsertQuery) Constraint(constraints ...string) *UpsertQuery {
u.constraints = constraints
return u
}
// Column sets the columns to update if an insert does't happen.
// If empty, all columns not being used for constraints will be updated.
// Cannot overlap with Constraint.
func (u *UpsertQuery) Column(columns ...string) *UpsertQuery {
u.columns = columns
return u
}
// insertDialect errors if we're using a dialect in which we don't know how to upsert.
func (u *UpsertQuery) insertDialect() error {
dialectName := u.db.Dialect().Name()
switch dialectName {
case dialect.PG, dialect.SQLite:
return nil
default:
// FUTURE: MySQL has its own variation on upserts, but the syntax is different.
return gtserror.Newf("UpsertQuery: upsert not supported by SQL dialect: %s", dialectName)
}
}
// insertConstraints checks that we have constraints and returns them.
func (u *UpsertQuery) insertConstraints() ([]string, error) {
if len(u.constraints) == 0 {
return nil, gtserror.New("UpsertQuery: upserts require at least one constraint column or index, none provided")
}
return u.constraints, nil
}
// insertColumns returns the non-constraint columns we'll be updating.
func (u *UpsertQuery) insertColumns(constraints []string) ([]string, error) {
// Constraints as a set.
constraintSet := make(map[string]struct{}, len(constraints))
for _, constraint := range constraints {
constraintSet[constraint] = struct{}{}
}
var columns []string
var err error
if len(u.columns) == 0 {
columns, err = u.insertColumnsDefault(constraintSet)
} else {
columns, err = u.insertColumnsSpecified(constraintSet)
}
if err != nil {
return nil, err
}
if len(columns) == 0 {
return nil, gtserror.New("UpsertQuery: there are no columns to update when upserting")
}
return columns, nil
}
// hasElem returns whether the type has an element and can call [reflect.Type.Elem] without panicking.
func hasElem(modelType reflect.Type) bool {
switch modelType.Kind() {
case reflect.Array, reflect.Chan, reflect.Map, reflect.Pointer, reflect.Slice:
return true
default:
return false
}
}
// insertColumnsDefault returns all non-constraint columns from the model schema.
func (u *UpsertQuery) insertColumnsDefault(constraintSet map[string]struct{}) ([]string, error) {
// Get underlying struct type.
modelType := reflect.TypeOf(u.model)
for hasElem(modelType) {
modelType = modelType.Elem()
}
table := u.db.Dialect().Tables().Get(modelType)
if table == nil {
return nil, gtserror.Newf("UpsertQuery: couldn't find the table schema for model: %v", u.model)
}
columns := make([]string, 0, len(u.columns))
for _, field := range table.Fields {
column := field.Name
if _, overlaps := constraintSet[column]; !overlaps {
columns = append(columns, column)
}
}
return columns, nil
}
// insertColumnsSpecified ensures constraints and specified columns to update don't overlap.
func (u *UpsertQuery) insertColumnsSpecified(constraintSet map[string]struct{}) ([]string, error) {
overlapping := make([]string, 0, min(len(u.constraints), len(u.columns)))
for _, column := range u.columns {
if _, overlaps := constraintSet[column]; overlaps {
overlapping = append(overlapping, column)
}
}
if len(overlapping) > 0 {
return nil, gtserror.Newf(
"UpsertQuery: the following columns can't be used for both constraints and columns to update: %s",
strings.Join(overlapping, ", "),
)
}
return u.columns, nil
}
// insert tries to create a Bun insert query from an upsert query.
func (u *UpsertQuery) insertQuery() (*bun.InsertQuery, error) {
var err error
err = u.insertDialect()
if err != nil {
return nil, err
}
constraints, err := u.insertConstraints()
if err != nil {
return nil, err
}
columns, err := u.insertColumns(constraints)
if err != nil {
return nil, err
}
// Build the parts of the query that need us to generate SQL.
constraintIDPlaceholders := make([]string, 0, len(constraints))
constraintIDs := make([]interface{}, 0, len(constraints))
for _, constraint := range constraints {
constraintIDPlaceholders = append(constraintIDPlaceholders, "?")
constraintIDs = append(constraintIDs, bun.Ident(constraint))
}
onSQL := "CONFLICT (" + strings.Join(constraintIDPlaceholders, ", ") + ") DO UPDATE"
setClauses := make([]string, 0, len(columns))
setIDs := make([]interface{}, 0, 2*len(columns))
for _, column := range columns {
setClauses = append(setClauses, "? = ?")
// "excluded" is a special table that contains only the row involved in a conflict.
setIDs = append(setIDs, bun.Ident(column), bun.Ident("excluded."+column))
}
setSQL := strings.Join(setClauses, ", ")
insertQuery := u.db.
NewInsert().
Model(u.model).
On(onSQL, constraintIDs...).
Set(setSQL, setIDs...)
return insertQuery, nil
}
// Exec builds a Bun insert query from the upsert query, and executes it.
func (u *UpsertQuery) Exec(ctx context.Context, dest ...interface{}) (sql.Result, error) {
insertQuery, err := u.insertQuery()
if err != nil {
return nil, err
}
return insertQuery.Exec(ctx, dest...)
}
// Scan builds a Bun insert query from the upsert query, and scans it.
func (u *UpsertQuery) Scan(ctx context.Context, dest ...interface{}) error {
insertQuery, err := u.insertQuery()
if err != nil {
return err
}
return insertQuery.Scan(ctx, dest...)
}