adapters

Documentation

Overview

Package adapters contains database specific code, mainly in sub-packages.

Index

• type Adapter
• type LimitBuilder
• type LimitOffsetOrderer
• type OffsetBuilder
• type PlaceholdersReplacer
• type ReturningBuilder
• type ReturningPosition
• type SQLPart

Types

type Adapter

type Adapter interface {
	// DriverName must return the driver name to be used with sql.Open()
	DriverName() string
	// Quote must return an SQL identifier (table name or column name) quoted.
	// Quote has not to split the string is multiple parts, this is done by
	// upper layers (it's common to different DB).
	// ie : "foo" for SQLite or Postgresql, `foo` for MySQL, [foo] for SQLServer.
	Quote(string) string
	// ParseError parses adapter errors and returns a understandable DBError
	ParseError(error) error
}

Adapter interface is the minimal implementation for an adapter.

type LimitBuilder

type LimitBuilder interface {
	BuildLimit(int) *SQLPart
}

LimitBuilder is an interface wrapping the optional BuildLimit method.

BuildLimit get an integer and returns a string containing a LIMIT sql clause or its equivalent for the adapter, and an array of sql arguments.

type LimitOffsetOrderer

type LimitOffsetOrderer interface {
	IsOffsetFirst() bool
}

LimitOffsetOrderer is an interface wrapping the optional IsOffsetFirst method.

The IsOffsetFirst returns true is the OFFSET clause has to precede the LIMIT clause. By default the LIMIT is before the OFFSET.

type OffsetBuilder

type OffsetBuilder interface {
	BuildOffset(int) *SQLPart
}

OffsetBuilder is an interface wrapping the optional BuildOffset method.

BuildOffset get an integer and returns a string containing an OFFSET sql clause or its equivalent for the adapter, and an array of sql arguments.

type PlaceholdersReplacer

type PlaceholdersReplacer interface {
	ReplacePlaceholders(string, string) string
}

PlaceholdersReplacer is an interface wrapping the optional ReplacePlaceholders method.

ReplacePlaceholders changes all given placeholders in given sql query with the placeholder used by the database targeted by the adapter.

type ReturningBuilder

type ReturningBuilder interface {
	ReturningBuild([]string) string
	FormatForNewValues([]string) []string
	GetReturningPosition() ReturningPosition
}

ReturningBuilder is an interface wrapping the optional ReturningBuild and ReturningNewValues method.

ReturningBuild gets a list of expressions and returns a clause to be added to the sql statement by the caller, allowing it to retrieve the values of those expressions.

It is intended to either replace the use of LastInsertId() when the driver does not support it, or to fetch all fields initialized or updated by the database itself. PostgreSQL and SQL Server are concerned with the RETURNING and OUTPUT clauses.

FormatForNewValues get a list of columns and format all of them to have expressions returning new values. The purpose is to always get new values when the database could either return the old or new values (before/after execution of the sql statement).

type ReturningPosition

type ReturningPosition int

ReturningPosition specify the position of the returning clause if the sql statement.

It's not abstract enough, some things are too coupled. Changing that will need a huge rewrite of godb, then now it does the trick.

const (
	// ReturningPostgreSQL for PostgreSQL
	ReturningPostgreSQL ReturningPosition = 1
	// ReturningSQLServer for SQL Server
	ReturningSQLServer = 2
)

type SQLPart

type SQLPart struct {
	Sql       string
	Arguments []interface{}
}

SQLPart is a struct containing a custom part of SQL query builded by an adapter.