mirror of
https://github.com/hasura/graphql-engine.git
synced 2024-12-18 04:51:35 +03:00
86 lines
4.2 KiB
ReStructuredText
86 lines
4.2 KiB
ReStructuredText
.. meta::
|
|
:description: Manage relationships between tables/views in Hasura
|
|
:keywords: hasura, docs, schema, relationship
|
|
|
|
.. _relationships:
|
|
|
|
Relationships between tables/views
|
|
==================================
|
|
|
|
.. contents:: Table of contents
|
|
:backlinks: none
|
|
:depth: 1
|
|
:local:
|
|
|
|
To make :ref:`nested object queries <nested_object_queries>`, the tables/views in your database need to
|
|
be connected via relationships.
|
|
|
|
Let's say we have the following tables in our database: ``author``, ``passport_info``, ``article`` and ``tag``.
|
|
|
|
.. _table_relationships:
|
|
|
|
Table relationships
|
|
-------------------
|
|
|
|
The tables/views in any relational database are typically related to each other via one of the
|
|
following types of table relationships:
|
|
|
|
+------------------+-----------------------------------+------------------------------------------------+
|
|
| Type | Example | Meaning |
|
|
+==================+===================================+================================================+
|
|
| ``one-to-one`` | ``author`` and ``passport_info`` | - an ``author`` can have one ``passport_info`` |
|
|
| | | - a ``passport_info`` can have one ``owner`` |
|
|
+------------------+-----------------------------------+------------------------------------------------+
|
|
| ``one-to-many`` | ``author`` and ``article`` | - an ``author`` can have many ``articles`` |
|
|
| | | - an ``article`` can have one ``author`` |
|
|
+------------------+-----------------------------------+------------------------------------------------+
|
|
| ``many-to-many`` | ``article`` and ``tag`` | - an ``article`` can have many ``tags`` |
|
|
| | | - a ``tag`` can have many ``articles`` |
|
|
+------------------+-----------------------------------+------------------------------------------------+
|
|
|
|
.. _graphql_relationships:
|
|
|
|
GraphQL schema relationships
|
|
----------------------------
|
|
|
|
Each table relationship, as you can see from the above section, will have two component relationships
|
|
(one in either direction) in the GraphQL schema. These relationships can be one of the following types:
|
|
|
|
+-----------------------------------------+------------------------------------------+---------------------------------------------------------------------------------------+
|
|
| Type | Example | Meaning |
|
|
+=========================================+==========================================+=======================================================================================+
|
|
| ``object relationship`` (one-to-one) | an ``article`` can have one ``author`` | an ``article`` object will have a single nested author object called ``author`` |
|
|
+-----------------------------------------+------------------------------------------+---------------------------------------------------------------------------------------+
|
|
| ``array relationship`` (one-to-many) | an ``author`` can have many ``articles`` | an ``author`` object will have an array of nested article objects called ``articles`` |
|
|
+-----------------------------------------+------------------------------------------+---------------------------------------------------------------------------------------+
|
|
|
|
.. note::
|
|
|
|
The relationship name is used to refer to the nested objects in queries. For example, "``articles``" of an ``author``
|
|
and "``author``" of an ``article``.
|
|
|
|
Managing GraphQL relationships
|
|
------------------------------
|
|
|
|
See the following to manage the object/array relationships between tables/views for the GraphQL schema:
|
|
|
|
- :ref:`create_relationships`
|
|
- :ref:`rename_relationships`
|
|
|
|
Table relationships modelling guides
|
|
------------------------------------
|
|
|
|
The following guides will help you model the different types of table relationships in the database:
|
|
|
|
- :ref:`one_to_one_modelling`
|
|
- :ref:`one_to_many_modelling`
|
|
- :ref:`many_to_many_modelling`
|
|
|
|
.. toctree::
|
|
:maxdepth: 1
|
|
:hidden:
|
|
|
|
create
|
|
rename
|
|
Database modelling <database-modelling/index>
|