graphql-engine/docs/graphql/manual/actions/create.rst
Karthikeyan Chinnakonda 5116e16e18
server(actions): add support for queries (close #4032) (#4309)
* add support for action queries

* a new parameter `type` is added in the ArgumentDefinition, its value
  can be either `query` or `mutation` and it defaults to the latter

* throw 400 when a query action is tried to explain

* update the actions docs to include query actions

* refactor the ToJSON and ToOrdJSON of ActionDefinition

Co-authored-by: Rishichandra Wawhal <rishi@hasura.io>
Co-authored-by: Tirumarai Selvan <tiru@hasura.io>
2020-04-16 12:55:19 +05:30

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.. meta::
:description: Creating Hasura actions
:keywords: hasura, docs, actions, create
.. _create_actions:
Creating actions
================
.. contents:: Table of contents
:backlinks: none
:depth: 1
:local:
Introduction
------------
An action is a GraphQL query or mutation. You have to define the GraphQL type of the
arguments that the query or mutation accepts and the GraphQL type of its response.
To create an action, you have to:
1. Define the query or mutation
2. Define the required types
3. Create a handler
Let's look at **examples** for mutation and query type actions.
Setup
-----
.. rst-class:: api_tabs
.. tabs::
.. tab:: Console
There is no setup required for defining actions via the console.
.. tab:: CLI
.. :ref:`Install <install_hasura_cli>` or :ref:`update to <hasura_update-cli>` the latest version of Hasura CLI.
Download the latest pre-release CLI version from the `releases page <https://github.com/hasura/graphql-engine/releases>`_
You can either get started with an existing project or create a new project.
**For a new project**
.. code-block:: bash
hasura init
This will create a new project. You can set up your GraphQL engine endpoint
(and admin secret if it exists) in the ``config.yaml``.
Run ``hasura metadata export`` so that you get server's metadata into the
``metadata/`` directory.
**For existing projects**
Actions are supported only in the v2 config of the CLI. Check the ``config.yaml``
of your Hasura project for the ``version`` key.
If you are in ``version: 1``, actions commands are not supported. Upgrade to
version 2 by running:
.. code-block:: bash
hasura scripts update-config-v2
Run ``hasura metadata export`` so that you get server's metadata into the
``metadata/`` directory.
Mutation type action
--------------------
Let's start with a mutation that accepts a username and password, and returns
an access token. We'll call this mutation ``login``.
Step 1: Define your mutation and associated types
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Start with defining the mutation and the required types. These types will reflect in the GraphQL schema.
.. rst-class:: api_tabs
.. tabs::
.. tab:: Console
Go to the ``Actions`` tab on the console and click on ``Create``. This will
take you to a page like this:
.. thumbnail:: ../../../img/graphql/manual/actions/action-create-page.png
:alt: Console action create
Define the action as follows in the ``Action Definition`` editor.
.. code-block:: graphql
type Mutation {
login (username: String!, password: String!): LoginResponse
}
In the above action, we called the returning object type to be ``LoginResponse``.
Define it in the ``New types definition`` as:
.. code-block:: graphql
type LoginResponse {
accessToken: String!
}
.. tab:: CLI
To create an action, run
.. code-block:: bash
hasura actions create login
This will open up an editor with ``metadata/actions.graphql``. You can enter
the action's mutation definition and the required types in this file. For your
``login`` mutation, replace the content of this file with the following
and save:
.. code-block:: graphql
type Mutation {
login (username: String!, password: String!): LoginResponse
}
type LoginResponse {
accessToken: String!
}
The above definition means:
* This action will be available in your GraphQL schema as a mutation called ``login``.
* It accepts two arguments called ``username`` and ``password`` of type ``String!``.
* It returns an output type called ``LoginResponse``.
* ``LoginResponse`` is a simple object type with a field called ``accessToken`` of type ``String!``.
Step 2: Create the action handler
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A handler is an HTTP webhook where you can perform the custom logic for the
action. In this case, we will just return an access token, but typically you would want to run all the business logic that the action demands. NodeJS/Express code
for this handler would look something like:
.. code-block:: js
const handler = (req, resp) => {
// You can access their arguments input at req.body.input
const { username, password } = req.body.input;
// perform your custom business logic
// check if the username and password are valid and login the user
// return the response
return resp.json({
accessToken: "Ew8jkGCNDGAo7p35RV72e0Lk3RGJoJKB"
})
};
You can deploy this code somewhere and get the URI. For getting started quickly, we
also have this handler ready at ``https://hasura-actions-starter-kit.glitch.me/login``.
**Set the handler**
Now, set the handler for the action:
.. rst-class:: api_tabs
.. tabs::
.. tab:: Console
Set the value of the ``handler`` field to the above endpoint.
.. tab:: CLI
Go to ``metadata/actions.yaml``. You must see a handler like ``http://localhost:3000``
or ``http://host.docker.internal:3000`` under the action named ``login``.
This is a default value taken from ``config.yaml``.
Update the ``handler`` to the above endpoint.
.. admonition:: URL templating
To manage handler endpoints across environments it is possible to template
the endpoints using ENV variables.
e.g. ``https://my-handler-endpoint/addNumbers`` can be templated to ``{{ACTION_BASE_ENDPOINT}}/addNumbers``
where ``ACTION_BASE_ENDPOINT`` is an ENV variable whose value is set to ``https://my-handler-endpoint``
Step 3: Finish action creation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Finally, to save the action:
.. rst-class:: api_tabs
.. tabs::
.. tab:: Console
Hit ``Create``.
.. tab:: CLI
Run ``hasura metadata apply``.
Step 4: Try it out
~~~~~~~~~~~~~~~~~~
In the Hasura console, head to the ``GraphiQL`` tab and try out the new action.
.. graphiql::
:view_only:
:query:
mutation {
login (username: "jondoe", password: "mysecretpassword") {
accessToken
}
}
:response:
{
"data": {
"login": {
"accessToken": "Ew8jkGCNDGAo7p35RV72e0Lk3RGJoJKB"
}
}
}
And that's it. You have extended your Hasura schema with a new mutation.
Query type action
-----------------
Let's start with a basic query that accepts a list of numbers and returns
their sum. We'll call this query ``addNumbers``.
Step 1: Define your query and associated types
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Start with defining the query and the required types. These types will reflect in the GraphQL schema.
.. rst-class:: api_tabs
.. tabs::
.. tab:: Console
Go to the ``Actions`` tab on the console and click on ``Create``. This will
take you to a page like this:
.. thumbnail:: ../../../img/graphql/manual/actions/action-create-page.png
:alt: Console action create
Define the action as follows in the ``Action Definition`` editor.
.. code-block:: graphql
type Query {
addNumbers (numbers: [Int]): AddResult
}
In the above action, we called the returning object type to be ``AddResult``.
Define it in the ``New types definition`` as:
.. code-block:: graphql
type AddResult {
sum: Int
}
.. tab:: CLI
To create an action, run
.. code-block:: bash
hasura actions create addNumbers
This will open up an editor with ``metadata/actions.graphql``. You can enter
the action's query definition and the required types in this file. For your
``addNumbers`` query, replace the content of this file with the following
and save:
.. code-block:: graphql
type Query {
addNumbers (numbers: [Int]): AddResult
}
type AddResult {
sum: Int
}
The above definition means:
* This action will be available in your GraphQL schema as a query called ``addNumbers``
* It accepts an argument called ``numbers`` which is a list of integers.
* It returns an output type called ``AddResult``.
* ``AddResult`` is a simple object type with a field called ``sum`` of type integer.
Step 2: Create the action handler
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A handler is an HTTP webhook where you can perform the custom logic for the
action. In this case, it is the addition of the numbers. NodeJS/Express code
for this handler would look something like:
.. code-block:: js
const handler = (req, resp) => {
// You can access their arguments input at req.body.input
const { numbers } = req.body.input;
// perform your custom business logic
// return an error or response
try {
return resp.json({
sum: numbers.reduce((s, n) => s + n, 0)
});
} catch(e) {
console.error(e)
return resp.status(500).json({
message: 'unexpected'
})
}
};
You can deploy this code somewhere and get the URI. For getting started quickly, we
also have this handler ready at ``https://hasura-actions-starter-kit.glitch.me/addNumbers``.
**Set the handler**
Now, set the handler for the action:
.. rst-class:: api_tabs
.. tabs::
.. tab:: Console
Set the value of the ``handler`` field to the above endpoint.
.. tab:: CLI
Go to ``metadata/actions.yaml``. You must see a handler like ``http://localhost:3000``
or ``http://host.docker.internal:3000`` under the action named ``addNumbers``.
This is a default value taken from ``config.yaml``.
Update the ``handler`` to the above endpoint.
.. admonition:: URL templating
To manage handler endpoints across environments it is possible to template
the endpoints using ENV variables.
e.g. ``https://my-handler-endpoint/addNumbers`` can be templated to ``{{ACTION_BASE_ENDPOINT}}/addNumbers``
where ``ACTION_BASE_ENDPOINT`` is an ENV variable whose value is set to ``https://my-handler-endpoint``
Step 3: Finish action creation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Finally, to save the action:
.. rst-class:: api_tabs
.. tabs::
.. tab:: Console
Hit ``Create``.
.. tab:: CLI
Run ``hasura metadata apply``.
Step 4: Try it out
~~~~~~~~~~~~~~~~~~
In the Hasura console, head to the ``GraphiQL`` tab and try out the new action.
.. graphiql::
:view_only:
:query:
query {
addNumbers(numbers: [1, 2, 3, 4]) {
sum
}
}
:response:
{
"data": {
"addNumbers": {
"sum": 10
}
}
}
And that's it. You have extended your Hasura schema with a new query.