EdgeDB supports GraphQL queries via the built-in graphql extension. A
full CRUD API for all object types, their properties (both material and
computed), their links, and all aliases is
reflected in the GraphQL schema.
In order to set up GraphQL access to the database, add the following to the schema:
using extension graphql;Then create a new migration and apply it.
$
edgedb migration create$
edgedb migrateRefer to the connection docs for various methods of running these commands against remotely-hosted instances.
Once you’ve activated the extension, your instance will listen for incoming GraphQL queries via HTTP at the following URL.
http://127.0.0.1:<instance-port>/db/<database-name>/graphql
The value of <database-name> is probably edgedb, which is the name of
the default database that is created when an instance is first created. (If
you’ve manually created additional databases, use the name of the database
you’d like to query instead.)
To find the port number associated with a local instance, run edgedb
instance list.
$
edgedb instance list┌────────┬──────────────┬──────────┬───────────────┬─────────────┐ │ Kind │ Name │ Port │ Version │ Status │ ├────────┼──────────────┼──────────┼───────────────┼─────────────┤ │ local │ inst1 │ 10700 │ 2.x │ running │ │ local │ inst2 │ 10702 │ 2.x │ running │ │ local │ inst3 │ 10703 │ 2.x │ running │ └────────┴──────────────┴──────────┴───────────────┴─────────────┘
To execute a GraphQL query against the database edgedb on the instance
named inst2, we would send an HTTP request to
http://localhost:10702/db/edgedb/graphql.
The endpoint also provides a GraphiQL interface to explore the GraphQL
schema and write queries. Take the GraphQL query endpoint, append
/explore, and visit that URL in the browser. Under the above example,
the GraphiQL endpoint is available at
http://localhost:10702/db/edgedb/graphql/explore.
But what kind of HTTP request should this be? And what data should it contain?
EdgeDB can recieve GraphQL queries via both GET and POST requests.
Requests can contain the following fields:
query - the GraphQL query string
variables - a JSON object containing a set of variables. Optional
If the GraphQL query string contains variables, the variables object is
required.
globals - a JSON object containing global variables. Optional. The
keys must be the fully qualified names of the globals to set (e.g.,
default::current_user for the global current_user in the default
module).
operationName - the name of the operation that must be
executed. Optional If the GraphQL query contains several named
operations, it is required.
The protocol implementations conform to the official GraphQL HTTP protocol. The protocol supports
HTTP Keep-Alive.
The POST request should use application/json content type and
submit the following JSON-encoded form with the necessary fields.
$
curl \
-H "Content-Type: application/json" \
-X POST http://localhost:10787/db/edgedb/graphql \
-d '{ "query": "query getMovie($title: String!) { Movie(filter: {title:{eq: $title}}) { id title }}", "variables": { "title": "The Batman" }, "globals": {"default::current_user": "04e52807-6835-4eaa-999b-952804ab40a5"}}'{"data": {...}}When using GET requests, any values for query, variables,
globals, or operationName should be passed as query parameters in the
URL.
$
curl \
-H application/x-www-form-urlencoded \
-X GET http://localhost:10787/db/edgedb/graphql \
-G \
--data-urlencode 'query=query getMovie($title: String!) { Movie(filter: {title:{eq: $title}}) { id title }}' \
--data-urlencode 'variables={ "title": "The Batman" }' --data-urlencode 'globals={ "default::current_user": "04e52807-6835-4eaa-999b-952804ab40a5" }'
{"data": {...}}The body of the response is JSON in the following format:
{
"data": { ... },
"errors": [
{ "message": "Error message"}, ...
]
}Note that the errors field will only be present if some errors
actually occurred.
Caution is advised when reading decimal or bigint values
(mapped onto Decimal and Bigint GraphQL custom scalar
types) using HTTP protocol because the results are provides in
JSON format. The JSON specification does not have a limit on
significant digits, so a decimal or a bigint number can be
losslessly represented in JSON. However, JSON decoders in many
languages will read all such numbers as some kind of of 32- or
64-bit number type, which may result in errors or precision loss.
If such loss is unacceptable, then consider creating a computed
property which casts the value into str and decoding it on the
client side into a more appropriate type.
We provide this GraphQL extension to support users who are accustomed to writing queries in GraphQL. That said, GraphQL is quite limited and verbose relative to EdgeQL.
There are also some additional limitations:
Variables can only correspond to scalar types; you can’t use
GraphQL input types. Under the hood, query variables are mapped onto
EdgeQL parameters, which only support scalar types.
As a consequence of this, you must declare top-level variables for each property for a GraphQL insertion mutation, which can make queries more verbose.
Due to the differences between EdgeQL and GraphQL syntax,
enum types which have values that cannot be
represented as GraphQL identifiers (e.g. `N/A` or `NOT
APPLICABLE`) cannot be properly reflected into GraphQL enums.
Inserting or updating tuple properties is not yet supported.
Link properties are not reflected, as GraphQL has no such concept.
Every non-abstract EdgeDB object type is simultaneously an interface and an object in terms of the GraphQL type system, which means that, for every one object type name, two names are needed in reflected GraphQL. This potentially results in name clashes if the convention of using camel-case names for user types is not followed in EdgeDB.
