mirror of
https://github.com/hasura/graphql-engine.git
synced 2024-12-17 20:41:49 +03:00
74 lines
3.3 KiB
ReStructuredText
74 lines
3.3 KiB
ReStructuredText
Setting up GraphQL schema using an existing database
|
|
====================================================
|
|
|
|
.. contents:: Table of contents
|
|
:backlinks: none
|
|
:depth: 1
|
|
:local:
|
|
|
|
When you have an existing database with a schema already present, you don't need to create tables or views or run
|
|
DDL queries through the Hasura console.
|
|
|
|
All you need to do is indicate to Hasura GraphQL engine which tables and views you want to expose over GraphQL and
|
|
how they are connected to each other so that you can query them as a "graph".
|
|
|
|
Step 1: Track tables/views
|
|
--------------------------
|
|
|
|
Tracking a table or a view means telling Hasura GraphQL engine that you want to expose that table/view over GraphQL.
|
|
|
|
To track a table or a view:
|
|
^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
#. Head to the ``Data -> Schema`` section of the console.
|
|
#. Under the heading ``Untracked Tables/Views``, click on the ``Add`` button next to the table/view name.
|
|
|
|
To track all tables and views present in the database:
|
|
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
#. Head to the ``Data -> Schema`` section of the console.
|
|
#. Under the heading ``Untracked Tables/Views``, click the ``Add all`` button.
|
|
|
|
Step 2: Track foreign-keys
|
|
--------------------------
|
|
|
|
Tracking a foreign-key means creating a :doc:`relationship <relationships/index>` between the tables involved in the
|
|
foreign-key.
|
|
|
|
To track a foreign-key between two tables in the database:
|
|
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
#. Head to the ``Data -> Schema`` section of the console.
|
|
#. Click on a table involved in the foreign-key and head to the ``Relationships`` tab.
|
|
#. You should see a suggested relationship based on the foreign-key. Click ``Add``, give a name to your relationship
|
|
(this will be the name of the :doc:`nested object <../queries/nested-object-queries>` in the GraphQL query), and
|
|
hit ``Save`` to create the relationship.
|
|
#. Repeat with the other table involved in the foreign-key.
|
|
|
|
|
|
To track all the foreign-keys of all tables in the database:
|
|
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
#. Head to the ``Data -> Schema`` section of the console.
|
|
#. Under the heading ``Untracked foreign-key relations``, click on the ``Track All Relations`` to automatically
|
|
create relationships based on the foreign-keys.
|
|
|
|
.. admonition:: Relationship nomenclature
|
|
|
|
In this case, Hasura GraphQL engine will **automatically generate relationship names** (the names of the
|
|
:doc:`nested objects <../queries/nested-object-queries>` in the GraphQL query) based on the table names and the
|
|
foreign-key names.
|
|
|
|
The name is generated in the following format:
|
|
|
|
- For object relationships: ``Camel case of (foreignTableName + By + columnName)``
|
|
- For array relationships: ``Camel case of (foreignTableName + s + By + columnNameInForeignTable)``
|
|
|
|
For example, for the foreign-key ``article::author_id -> author::id``, the relationship names will be
|
|
``authorByAuthorId`` for ``article`` table and ``articlesByAuthorId`` for ``author`` table.
|
|
|
|
Note that, **this is just an arbitrary naming convention** chosen by Hasura to ensure generation of unique
|
|
relationship names. You can choose to rename your relationships to anything you wish. You can **change the
|
|
relationship names** with a name of your choice as shown in :doc:`relationships/rename`.
|
|
|