graphql-engine/docs/graphql/manual/schema/custom-resolvers.rst
2018-09-11 16:41:24 +05:30

29 lines
1.2 KiB
ReStructuredText

Adding custom GraphQL resolvers
===============================
Hasura GraphQL engine provides instant GraphQL APIs over the tables and views of any Postgres database by
auto-generating the CRUD resolvers. However, sometimes you might have to write custom resolvers to capture business
logic that is unrelated to the database.
We have setup `this boilerplate project <https://github.com/hasura/custom-resolvers-boilerplate>`_ illustrating how to
write your own custom GraphQL resolvers and merge them with the Hasura GraphQL engine's resolvers.
Follow the boilerplate's ``README.md`` for detailed instructions.
TL;DR
-----
The boilerplate includes sample custom resolvers for:
- A ``hello`` query
- A ``count`` query (that returns a counter from another data source )
- A ``increment_counter`` mutation that increments the value of count
- A ``user_average_age`` query that makes directly makes an SQL query to Postgres using Knex
The steps to achieve this are:
- Create the query/mutation types for your custom GraphQL API.
- Write the custom resolver code for the above types.
- Make a new GraphQL schema out of these custom resolvers.
- Merge this schema with the existing Hasura GraphQL schema and serve the resulting GraphQL API.