libdal

package
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Published: Sep 20, 2024 License: Apache-2.0 Imports: 9 Imported by: 0

Documentation

Overview

Package libdal provides common types and functions for domain-specific DALs.

In particular, common error types and error handling function for all domain-specific DALs, e.g. controller DAL and configuration DAL, which all connect to the same underlying DB and maintain the same interface guarantees

Index

Constants

This section is empty.

Variables

View Source
var (
	// ErrConflict is returned by select methods in the DAL when a resource already exists.
	//
	// Its use will be documented in the corresponding methods.
	ErrConflict = errors.New("conflict")
	// ErrNotFound is returned by select methods in the DAL when no results are found.
	ErrNotFound = errors.New("not found")
	// ErrConstraint is returned by select methods in the DAL when a constraint is violated.
	ErrConstraint = errors.New("constraint violation")
)

Functions

func IsNotFound

func IsNotFound(err error) bool

func TranslatePGError

func TranslatePGError(err error) error

Types

type Connection

type Connection interface {
	ExecContext(ctx context.Context, query string, args ...interface{}) (sql.Result, error)
	PrepareContext(ctx context.Context, query string) (*sql.Stmt, error)
	QueryContext(ctx context.Context, query string, args ...interface{}) (*sql.Rows, error)
	QueryRowContext(ctx context.Context, query string, args ...interface{}) *sql.Row
}

Connection is a common interface for *sql.DB and *sql.Tx.

type Handle

type Handle[T any] struct {
	Connection Connection

	Make MakeWithHandle[T]
	// contains filtered or unexported fields
}

Handle is a wrapper around a database connection that can be embedded within a struct to provide access to a database connection and methods for managing transactions.

func New

func New[T any](sql Connection, fn MakeWithHandle[T]) *Handle[T]

New creates a new Handle

func (*Handle[T]) Begin

func (h *Handle[T]) Begin(ctx context.Context) (*T, error)

Begin creates a new transaction or increments the transaction counter if the handle is already in a transaction.

In all cases a new handle is returned.

func (*Handle[T]) Commit

func (h *Handle[T]) Commit(ctx context.Context) error

Commit the transaction or savepoint.

func (*Handle[T]) CommitOrRollback

func (h *Handle[T]) CommitOrRollback(ctx context.Context, err *error)

CommitOrRollback commits the transaction if err is nil, otherwise rolls it back.

Use it in a defer like so, particularly taking note of named return value `(err error)`. Without this it will not work.

func (d *DAL) SomeMethod() (err error) {
	tx, err := d.Begin()
	if err != nil { return err }
	defer tx.CommitOrRollback(&err)
	// ...
	return nil
}

func (*Handle[T]) Rollback

func (h *Handle[T]) Rollback(ctx context.Context) error

Rollback the transaction or savepoint.

type MakeWithHandle

type MakeWithHandle[T any] func(*Handle[T]) *T

MakeWithHandle is a function that can be used to create a new T with a SQLHandle.

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