@envelop/execute-subscription-event

@envelop/execute-subscription-event

Utilities for hooking into the
ExecuteSubscriptionEvent>) phase.

$3

Create a new context object per ExecuteSubscriptionEvent phase, allowing to bypass common issues
with context objects such as DataLoader
caching
issues.

``ts
import { execute, parse, specifiedRules, subscribe, validate } from 'graphql'
import { envelop, useEngine } from '@envelop/core'
import { useContextValuePerExecuteSubscriptionEvent } from '@envelop/execute-subscription-event'
import { createContext, createDataLoaders } from './context'

const getEnveloped = envelop({
plugins: [
useEngine({ parse, validate, specifiedRules, execute, subscribe }),
useContext(() => createContext()),
useContextValuePerExecuteSubscriptionEvent(() => ({
// Existing context is merged with this context partial
// By recreating the DataLoader we ensure no DataLoader caches from the previous event/initial field subscribe call are are hit
contextPartial: {
dataLoaders: createDataLoaders()
}
}))
// ... other plugins ...
]
})
`

Alternatively, you can also provide a callback that is invoked after each
ExecuteSubscriptionEvent>) phase.

`ts
import { execute, parse, specifiedRules, subscribe, validate } from 'graphql'
import { envelop, useEngine } from '@envelop/core'
import { useContextValuePerExecuteSubscriptionEvent } from '@envelop/execute-subscription-event'
import { createContext, createDataLoaders } from './context'

const getEnveloped = envelop({
plugins: [
useEngine({ parse, validate, specifiedRules, execute, subscribe }),
useContext(() => createContext()),
useContextValuePerExecuteSubscriptionEvent(({ args }) => ({
onEnd: () => {
// Note that onEnd is invoked only after each ExecuteSubscriptionEvent phase
// This means the initial event will still use the cache from potential subscribe dataloader calls
// If you use this to clear DataLoader caches it is recommended to not do any DataLoader calls within your field subscribe function.
args.contextValue.dataLoaders.users.clearAll()
args.contextValue.dataLoaders.posts.clearAll()
}
}))
// ... other plugins ...
]
})
``