blobio

Documentation

Overview

Package blobio provides an SQL interface to incremental BLOB I/O.

Example

// Open the database, registering the extension.
db, err := driver.Open("file:/test.db?vfs=memdb", blobio.Register)

if err != nil {
	log.Fatal(err)
}
defer db.Close()

_, err = db.Exec(`CREATE TABLE test (col)`)
if err != nil {
	log.Fatal(err)
}

const message = "Hello BLOB!"

// Create the BLOB.
r, err := db.Exec(`INSERT INTO test VALUES (?)`, sqlite3.ZeroBlob(len(message)))
if err != nil {
	log.Fatal(err)
}

id, err := r.LastInsertId()
if err != nil {
	log.Fatal(err)
}

// Write the BLOB.
_, err = db.Exec(`SELECT writeblob('main', 'test', 'col', ?, 0, ?)`,
	id, message)
if err != nil {
	log.Fatal(err)
}

// Read the BLOB.
_, err = db.Exec(`SELECT readblob('main', 'test', 'col', ?, 0, ?)`,
	id, sqlite3.Pointer(os.Stdout))
if err != nil {
	log.Fatal(err)
}

Output:

Hello BLOB!

Index

• func Register(db *sqlite3.Conn) error
• type OpenCallback

Examples

• Package

Functions

func Register

func Register(db *sqlite3.Conn) error

Register registers the SQL functions:

readblob(schema, table, column, rowid, offset, n/writer)

Reads n bytes of a blob, starting at offset.

writeblob(schema, table, column, rowid, offset, data/reader)

Writes data into a blob, at the given offset.

openblob(schema, table, column, rowid, write, callback, args...)

Opens blobs for reading or writing. The callback is invoked for each open blob, and must be bound to an OpenCallback, using sqlite3.BindPointer or sqlite3.Pointer. The optional args will be passed to the callback, along with the sqlite3.Blob handle. The sqlite3.Blob handle is only valid during the execution of the callback. Callers cannot read or write to the handle after the callback exits.

https://sqlite.org/c3ref/blob.html

Types

type OpenCallback

type OpenCallback func(*sqlite3.Blob, ...sqlite3.Value) error

OpenCallback is the type for the openblob callback.