class GLib::Relation

Overview

A GRelation is a table of data which can be indexed on any number of fields, rather like simple database tables. A GRelation contains a number of records, called tuples. Each record contains a number of fields. Records are not ordered, so it is not possible to find the record at a particular index.

Note that GRelation tables are currently limited to 2 fields.

To create a GRelation, use GLib::Relation.new.

To specify which fields should be indexed, use GLib::Relation#index. Note that this must be called before any tuples are added to the GRelation.

To add records to a GRelation use GLib::Relation#insert.

To determine if a given record appears in a GRelation, use GLib::Relation#exists. Note that fields are compared directly, so pointers must point to the exact same position (i.e. different copies of the same string will not match.)

To count the number of records which have a particular value in a given field, use GLib::Relation#count.

To get all the records which have a particular value in a given field, use GLib::Relation#select. To access fields of the resulting records, use GLib::Tuples#index. To free the resulting records use GLib::Tuples#destroy.

To delete all records which have a particular value in a given field, use GLib::Relation#delete.

To destroy the GRelation, use GLib::Relation#destroy.

To help debug GRelation objects, use GLib::Relation#print.

GRelation has been marked as deprecated, since this API has never been fully implemented, is not very actively maintained and rarely used.

Defined in:

lib/gi-crystal/src/auto/g_lib-2.0/relation.cr

Constructors

Instance Method Summary

Constructor Detail

def self.new(pointer : Pointer(Void), transfer : GICrystal::Transfer) #

Instance Method Detail

def count(key : Pointer(Void) | Nil, field : Int32) : Int32 #

DEPRECATED


def delete(key : Pointer(Void) | Nil, field : Int32) : Int32 #

DEPRECATED


def destroy : Nil #

DEPRECATED


def print : Nil #

DEPRECATED


def to_unsafe : Pointer(Void) #