Backend/Felipe Renato

[felipeourenato]

Feature Flags Graphql API

About the Database

Relationship: I choose a design that allows an N-to-N relationship between feature_flag and user_account entities. The idea is to link both data in a third entity called user_feature_flag where only one value is accepted for each combination of User and Feature Flag domains.

Feature Flag entity:

The feature_flag entity is composed of a simple unique property called feature_flag_key responsible for the description of a feature flag, followed by an autoincrement id and created_at properties.

User Feature Flag entity:

The user_feature_flag entity is composed of user_id and feature_flag_id foreign keys that references to user_account and feature_flag entities, respectively. The property feature_flag_value is a text property responsible for keeping the feature flag data.

About Graphql Queries and Mutations

• I created only one mutation setUsersFeatureFlagMutation which is able to target one or more users with a specific feature flag and also change the value of a feature flag for a specific user.

• The User query is responsible for loading the user_account data grouping user_feature_flag list inside it self by using a UserFeatureFlag resolver, which counts with a dataloader implementation to avoid excessive and unnecessary database requests for each user node.

Data Layer

To maintain the Data logic handlers abstracted from resolvers, I choose to create a Dasource composition where each exposed domain has an exclusive object with its own logic.

About tests

That was my first project with fastify and slonik (and I have no clue of how to inject a Postgre connection inside of it), so to keep it simple I just added unit tests on dto's adapter functions. But it would be a great evolution to this code to add integration tests.

To Watch My Loom Video:

Click Here!