auto-discovering-relationship.md

Auto Discovering Relationship

The FieldAttribute has a parameter parentTable that is used to define the parent table of the field. This is used in the case of a foreign key.

Once this attribute is set, the Repository can auto-discover the relationship between the tables and generate the proper SQL with the relationship to retrieve the data.

How to use

You can use the parentTable parameter in the FieldAttribute to define the parent table of the field.

<?php
#[TableAttribute('table1')]
class Class1
{
    #[FieldAttribute(primaryKey: true)]
    public ?int $id;
}

#[TableAttribute('table2')]
class Class2
{
    #[FieldAttribute(primaryKey: true)]
    public ?int $id;

    #[FieldAttribute(fieldName: "id_table1", parentTable: "table1")]
    public ?int $idTable1;
}

$repository1 = new Repository($dbDriver, Class1::class);
$repository2 = new Repository($dbDriver, Class2::class);

This will automatically create the relationship between table1 and table2.

To generate the SQL with the relationship you can use the ORM static class:

<?php
$query = ORM::getQueryInstance("table1", "table2");

The command above will return a query object similar to:

<?php
$query = Query::getInstance()
    ->table('table1')
    ->join('table2', 'table2.id_table1 = table1.id');

Limitations

• This feature does not support multiple relationships between the same tables
• Primary keys with two or more fields are not supported.