query

Documentation

Overview

Package query implements helpers around database/sql to execute various kinds of very common SQL queries.

Index

• func Count(tx *sql.Tx, table string, where string, args ...interface{}) (int, error)
• func CountAll(tx *sql.Tx) (map[string]int, error)
• func DeleteObject(tx *sql.Tx, table string, id int64) (bool, error)
• func Dump(tx *sql.Tx, schema string, schemaOnly bool) (string, error)
• func InsertStrings(tx *sql.Tx, stmt string, values []string) error
• func IsRetriableError(err error) bool
• func Params(n int) string
• func Retry(f func() error) error
• func SelectConfig(tx *sql.Tx, table string, where string, args ...interface{}) (map[string]string, error)
• func SelectIntegers(tx *sql.Tx, query string, args ...interface{}) ([]int, error)
• func SelectObjects(stmt *sql.Stmt, dest Dest, args ...interface{}) error
• func SelectStrings(tx *sql.Tx, query string, args ...interface{}) ([]string, error)
• func SelectURIs(stmt *sql.Stmt, f func(a ...interface{}) string, args ...interface{}) ([]string, error)
• func Transaction(db *sql.DB, f func(*sql.Tx) error) error
• func UpdateConfig(tx *sql.Tx, table string, values map[string]string) error
• func UpsertObject(tx *sql.Tx, table string, columns []string, values []interface{}) (int64, error)
• type Dest

Functions

func Count

func Count(tx *sql.Tx, table string, where string, args ...interface{}) (int, error)

Count returns the number of rows in the given table.

func CountAll

func CountAll(tx *sql.Tx) (map[string]int, error)

CountAll returns a map associating each table name in the database with the total count of its rows.

func DeleteObject

func DeleteObject(tx *sql.Tx, table string, id int64) (bool, error)

DeleteObject removes the row identified by the given ID. The given table must have a primary key column called 'id'.

It returns a flag indicating if a matching row was actually found and deleted or not.

func Dump

func Dump(tx *sql.Tx, schema string, schemaOnly bool) (string, error)

Dump returns a SQL text dump of all rows across all tables, similar to sqlite3's dump feature

func InsertStrings

func InsertStrings(tx *sql.Tx, stmt string, values []string) error

InsertStrings inserts a new row for each of the given strings, using the given insert statement template, which must define exactly one insertion column and one substitution placeholder for the values. For example: InsertStrings(tx, "INSERT INTO foo(name) VALUES %s", []string{"bar"}).

func IsRetriableError

func IsRetriableError(err error) bool

IsRetriableError returns true if the given error might be transient and the interaction can be safely retried.

func Params

func Params(n int) string

Params returns a parameters expression with the given number of '?' placeholders. E.g. Params(2) -> "(?, ?)". Useful for IN and VALUES expressions.

func Retry

func Retry(f func() error) error

Retry wraps a function that interacts with the database, and retries it in case a transient error is hit.

This should by typically used to wrap transactions.

func SelectConfig

func SelectConfig(tx *sql.Tx, table string, where string, args ...interface{}) (map[string]string, error)

SelectConfig executes a query statement against a "config" table, which must have 'key' and 'value' columns. By default this query returns all keys, but additional WHERE filters can be specified.

Returns a map of key names to their associated values.

func SelectIntegers

func SelectIntegers(tx *sql.Tx, query string, args ...interface{}) ([]int, error)

SelectIntegers executes a statement which must yield rows with a single integer column. It returns the list of column values.

func SelectObjects

func SelectObjects(stmt *sql.Stmt, dest Dest, args ...interface{}) error

SelectObjects executes a statement which must yield rows with a specific columns schema. It invokes the given Dest hook for each yielded row.

func SelectStrings

func SelectStrings(tx *sql.Tx, query string, args ...interface{}) ([]string, error)

SelectStrings executes a statement which must yield rows with a single string column. It returns the list of column values.

func SelectURIs

func SelectURIs(stmt *sql.Stmt, f func(a ...interface{}) string, args ...interface{}) ([]string, error)

SelectURIs returns a list of LXD API URI strings for the resource yielded by the given query.

The f argument must be a function that formats the entity URI using the columns yielded by the query.

func Transaction

func Transaction(db *sql.DB, f func(*sql.Tx) error) error

Transaction executes the given function within a database transaction.

func UpdateConfig

func UpdateConfig(tx *sql.Tx, table string, values map[string]string) error

UpdateConfig updates the given keys in the given table. Config keys set to empty values will be deleted.

func UpsertObject

func UpsertObject(tx *sql.Tx, table string, columns []string, values []interface{}) (int64, error)

UpsertObject inserts or replaces a new row with the given column values, to the given table using columns order. For example:

UpsertObject(tx, "cars", []string{"id", "brand"}, []interface{}{1, "ferrari"})

The number of elements in 'columns' must match the one in 'values'.

Types

type Dest

type Dest func(i int) []interface{}

Dest is a function that is expected to return the objects to pass to the 'dest' argument of sql.Rows.Scan(). It is invoked by SelectObjects once per yielded row, and it will be passed the index of the row being scanned.