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postgresql_helper.go
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postgresql_helper.go
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package testfixtures
import (
"database/sql"
"fmt"
"strings"
)
// PostgreSQLHelper is the PG helper for this package
type PostgreSQLHelper struct {
// UseAlterConstraint If true, the contraint disabling will do
// using ALTER CONTRAINT sintax, only allowed in PG >= 9.4.
// If false, the constraint disabling will use DISABLE TRIGGER ALL,
// which requires SUPERUSER privileges.
UseAlterConstraint bool
}
type pgContraint struct {
tableName string
constraintName string
}
func (PostgreSQLHelper) paramType() int {
return paramTypeDollar
}
func (PostgreSQLHelper) quoteKeyword(str string) string {
return fmt.Sprintf("\"%s\"", str)
}
func (PostgreSQLHelper) databaseName(db *sql.DB) (dbName string) {
db.QueryRow("SELECT current_database()").Scan(&dbName)
return
}
func (h *PostgreSQLHelper) getTables(db *sql.DB) ([]string, error) {
var tables []string
sql := `
SELECT table_name
FROM information_schema.tables
WHERE table_schema='public'
AND table_type='BASE TABLE';
`
rows, err := db.Query(sql)
if err != nil {
return nil, err
}
defer rows.Close()
for rows.Next() {
var table string
rows.Scan(&table)
tables = append(tables, table)
}
return tables, nil
}
func (h *PostgreSQLHelper) getSequences(db *sql.DB) ([]string, error) {
var sequences []string
sql := "SELECT relname FROM pg_class WHERE relkind = 'S'"
rows, err := db.Query(sql)
if err != nil {
return nil, err
}
defer rows.Close()
for rows.Next() {
var sequence string
err = rows.Scan(&sequence)
if err != nil {
return nil, err
}
sequences = append(sequences, sequence)
}
return sequences, nil
}
func (PostgreSQLHelper) getNonDeferrableConstraints(db *sql.DB) ([]pgContraint, error) {
var constraints []pgContraint
sql := `
SELECT table_name, constraint_name
FROM information_schema.table_constraints
WHERE constraint_type = 'FOREIGN KEY'
AND is_deferrable = 'NO'`
rows, err := db.Query(sql)
if err != nil {
return nil, err
}
defer rows.Close()
for rows.Next() {
var constraint pgContraint
err = rows.Scan(&constraint.tableName, &constraint.constraintName)
if err != nil {
return nil, err
}
constraints = append(constraints, constraint)
}
return constraints, nil
}
func (h *PostgreSQLHelper) disableTriggers(db *sql.DB, loadFn loadFunction) error {
tables, err := h.getTables(db)
if err != nil {
return err
}
defer func() {
// re-enable triggers after load
var sql string
for _, table := range tables {
sql += fmt.Sprintf("ALTER TABLE %s ENABLE TRIGGER ALL;", h.quoteKeyword(table))
}
db.Exec(sql)
}()
tx, err := db.Begin()
if err != nil {
return err
}
var sql string
for _, table := range tables {
sql += fmt.Sprintf("ALTER TABLE %s DISABLE TRIGGER ALL;", h.quoteKeyword(table))
}
_, err = tx.Exec(sql)
if err != nil {
return err
}
err = loadFn(tx)
if err != nil {
tx.Rollback()
return err
}
err = tx.Commit()
return err
}
func (h *PostgreSQLHelper) makeConstraintsDeferrable(db *sql.DB, loadFn loadFunction) error {
nonDeferrableConstraints, err := h.getNonDeferrableConstraints(db)
if err != nil {
return err
}
defer func() {
// ensure constraint being not deferrable again after load
var sql string
for _, constraint := range nonDeferrableConstraints {
sql += fmt.Sprintf("ALTER TABLE %s ALTER CONSTRAINT %s NOT DEFERRABLE;", h.quoteKeyword(constraint.tableName), h.quoteKeyword(constraint.constraintName))
}
db.Exec(sql)
}()
var sql string
for _, constraint := range nonDeferrableConstraints {
sql += fmt.Sprintf("ALTER TABLE %s ALTER CONSTRAINT %s DEFERRABLE;", h.quoteKeyword(constraint.tableName), h.quoteKeyword(constraint.constraintName))
}
_, err = db.Exec(sql)
if err != nil {
return err
}
tx, err := db.Begin()
if err != nil {
return err
}
_, err = tx.Exec("SET CONSTRAINTS ALL DEFERRED")
if err != nil {
return nil
}
err = loadFn(tx)
if err != nil {
tx.Rollback()
return err
}
err = tx.Commit()
return err
}
func (h *PostgreSQLHelper) disableReferentialIntegrity(db *sql.DB, loadFn loadFunction) error {
// ensure sequences being reset after load
defer h.resetSequences(db)
if h.UseAlterConstraint {
return h.makeConstraintsDeferrable(db, loadFn)
} else {
return h.disableTriggers(db, loadFn)
}
}
func (h *PostgreSQLHelper) resetSequences(db *sql.DB) error {
sequences, err := h.getSequences(db)
if err != nil {
return err
}
for _, sequence := range sequences {
var max int
table := strings.Replace(sequence, "_id_seq", "", 1)
row := db.QueryRow(fmt.Sprintf("SELECT COALESCE(MAX(id), 0) FROM %s", h.quoteKeyword(table)))
err = row.Scan(&max)
if err != nil {
return err
}
if max == 0 {
max = 1
}
_, err = db.Exec(fmt.Sprintf("SELECT SETVAL('%s', %d)", sequence, max))
if err != nil {
return err
}
}
return nil
}