The GitHub GraphQL API represents an architectural and conceptual shift from the GitHub REST API. You will likely encounter some new terminology in the GraphQL API
reference docs
.
A schema defines a GraphQL API's type system. It describes the complete set of possible data (objects, fields, relationships, everything) that a client can access. Calls from the client are
validated
and
executed
against the schema. A client can find information about the schema via
introspection
. A schema resides on the GraphQL API server. For more information, see "
Discovering the GraphQL API
."
A field is a unit of data you can retrieve from an object. As the
official GraphQL docs
say:
"The GraphQL query language is basically about selecting fields on objects."
The
official spec
also says about fields:
All GraphQL operations must specify their selections down to fields which return scalar values to ensure an unambiguously shaped response.
This means that if you try to return a field that is not a scalar, schema validation will throw an error. You must add nested subfields until all fields return scalars.
An argument is a set of key-value pairs attached to a specific field. Some fields require an argument.
Mutations
require an input object as an argument.
A GraphQL schema may use the term
implements
to define how an object inherits from an
interface
.
Here's a contrived example of a schema that defines interface
X
and object
Y
:
interface
X
{
some_field
:
String
!
other_field
:
String
!
}
type
Y implements X
{
some_field
:
String
!
other_field
:
String
!
new_field
:
String
!
}
This means object
Y
requires the same fields/arguments/return types that interface
X
does, while adding new fields specific to object
Y
. (The
!
means the field is required.)
In the reference docs, you'll find that:
Connections let you query related objects as part of the same call. With connections, you can use a single GraphQL call where you would have to use multiple calls to a REST API. For more information, see "
Migrating from REST to GraphQL
."
It's helpful to picture a graph: dots connected by lines. The dots are nodes, the lines are edges. A connection defines a relationship between nodes.
Edges represent connections between nodes. When you query a connection, you traverse its edges to get to its nodes. Every
edges
field has a
node
field and a
cursor
field. Cursors are used for pagination. For more information, see "
Using pagination in the GraphQL API
."
Node
is a generic term for an object. You can look up a node directly, or you can access related nodes via a connection. If you specify a
node
that does not return a
scalar
, you must include subfields until all fields return scalars. For information on accessing node IDs via the REST API and using them in GraphQL queries, see "
Using global node IDs
."
GraphQL is
introspective
. This means you can query a GraphQL schema for details about itself.
-
Query
__schema
to list all types defined in the schema and get details about each:
query
{
__schema
{
types
{
name
kind
description
fields
{
name
}
}
}
}
-
Query
__type
to get details about any type:
query
{
__type
(
name
:
"Repository"
)
{
name
kind
description
fields
{
name
}
}
}
-
You can also run an
introspection query
of the schema via a
GET
request:
curl -H "Authorization: bearer TOKEN" https://api.github.com/graphql
Note
: If you get the response
"message": "Bad credentials"
or
401 Unauthorized
, check that you are using a valid token. If you receive a
403
error with
Resource not accessible by personal access token
, ensure that your fine-grained personal access token is targeted to the correct resource owner. For example, it must target the organization that owns the repository you are trying to access.
The results are in JSON, so we recommend pretty-printing them for easier reading and searching. You can use a command-line tool like
jq
or pipe the results into
python -m json.tool
for this purpose.
Alternatively, you can pass the
idl
media type to return the results in IDL format, which is a condensed version of the schema:
$
curl -H
"Authorization: bearer TOKEN"
-H
"Accept: application/vnd.github.v4.idl"
\
https://api.github.com/graphql
Note
: The introspection query is probably the only
GET
request you'll run in GraphQL. If you're passing a body, the GraphQL request method is
POST
, whether it's a query or a mutation.
For more information about performing queries, see "
Forming calls with GraphQL
."