Key Fields

In order to know which fields identify individual resources in your schema Stellate needs to know which field holds the unique identifier for a certain node type. This is mainly used for purging changed results from the cache, either via automatic cache invalidation or the Purging API

By default, Stellate looks for id, _id and key fields on your types. However, sometimes you have other unique fields (like e.g. User.email) that you want to use for this purpose.

To tell the Stellate Edge Cache that email is a field that uniquely identifies resources, Key Fields can be defined in the Stellate configuration file.

The keyFields field can be used like so:

import { Config } from 'stellate'
 
const config: Config = {
  config: {
    keyFields: {
      types: {
        NewsLetterSubscriber: ['id', 'email'],
      },
    },
  },
}
export default config

These key fields are then immediately exposed and purgeable via the purging API:

# Purge newsletter subscriber with the email max@stellate.co
mutation {
  purgeNewsletterSubscriber(email: ["max@stellate.co"])
}

For more information about cache purging and the purging API read the documentation on the Purging API.

Changing default key-fields

By default we’ll check for keys at id, _id and key on your responses, however sometimes you might need to change this when you use something along the lines of idx, if that’s the case you can add the following config

import { Config } from 'stellate'
 
const config: Config = {
  config: {
    keyFields: {
      defaults: ['idx', 'id', '_id', 'key'],
      types: {},
    },
  },
}
export default config

this will add your own custom identifier to the surrogate-keys.