feathersHooks ​
Generating a hook ​
A new hook can be generated via
npx feathers generate hook
npx feathers generate hook
Hook name ​
The hook generator will first ask for a name. Based on the name it will create a kebab-cased filename in the hooks/ folder that exports a camelCased hook function. For example a name of my fancy Hook will create a src/my-fancy-hook.ts file that exports a myFancyHook hook function.
Hook types ​
There are two hook types that can be generated.
tip
For more information see the hooks API documentation.
Around hooks ​
Around hooks allow to control the entire before, after and error flow in a single function. An around hook is an async function that accepts two arguments:
- The hook context
- An asynchronous
nextfunction. Somewhere in the body of the hook function, there is a call toawait next(), which calls thenexthooks OR the original function if all other hooks have run.
import type { HookContext, NextFunction } from '../declarations'
export const myFancyHook = async (context: HookContext, next: NextFunction) => {
console.log(`Running hook ${name} on ${context.path}.${context.method}`)
await next()
// Do things after here
}
import type { HookContext, NextFunction } from '../declarations'
export const myFancyHook = async (context: HookContext, next: NextFunction) => {
console.log(`Running hook ${name} on ${context.path}.${context.method}`)
await next()
// Do things after here
}
export const myFancyHook = async (context, next) => {
console.log(`Running hook ${name} on ${context.path}.${context.method}`)
await next()
// Do things after here
}
export const myFancyHook = async (context, next) => {
console.log(`Running hook ${name} on ${context.path}.${context.method}`)
await next()
// Do things after here
}
You can wrap the await next() in a try/catch block to also handle errors.
Before, after, error ​
Before, after or error hooks are async functions that take the hook context as the parameter.
import type { HookContext } from '../declarations'
export const myFancyHook = async (context: HookContext) => {
console.log(`Running hook ${name} on ${context.path}.${context.method}`)
}
import type { HookContext } from '../declarations'
export const myFancyHook = async (context: HookContext) => {
console.log(`Running hook ${name} on ${context.path}.${context.method}`)
}
export const myFancyHook = async (context) => {
console.log(`Running hook ${name} on ${context.path}.${context.method}`)
}
export const myFancyHook = async (context) => {
console.log(`Running hook ${name} on ${context.path}.${context.method}`)
}
Context types ​
If the hook is for a specific service, you can pass the service as a generic to the HookContext type which will give you the correct types for context.data, context.result and context.params:
import type { UserService } from '../services/users/users'
import type { HookContext } from '../declarations'
export const myFancyUserHook = async (context: HookContext<UserService>) => {
console.log(`Running hook ${name} on ${context.path}.${context.method}`)
}
import type { UserService } from '../services/users/users'
import type { HookContext } from '../declarations'
export const myFancyUserHook = async (context: HookContext<UserService>) => {
console.log(`Running hook ${name} on ${context.path}.${context.method}`)
}
export const myFancyUserHook = async (context) => {
console.log(`Running hook ${name} on ${context.path}.${context.method}`)
}
export const myFancyUserHook = async (context) => {
console.log(`Running hook ${name} on ${context.path}.${context.method}`)
}
Registering hooks ​
A generated hook can be registered as an application hook or as a service hook. Also see the hook registration API documentation.
Profiling example ​
To log some basic profiling information like which method was called and how long it took to run you can create a new around hook called profiler via
npx feathers generate hook
npx feathers generate hook
Then update src/hooks/profiler.ts as follows:
import type { HookContext, NextFunction } from '../declarations'
import { logger } from '../logger'
export const profiler = async (context: HookContext, next: NextFunction) => {
const startTime = Date.now()
await next()
const runtime = Date.now() - startTime
console.log(`Calling ${context.method} on service ${context.path} took ${runtime}ms`)
}
import type { HookContext, NextFunction } from '../declarations'
import { logger } from '../logger'
export const profiler = async (context: HookContext, next: NextFunction) => {
const startTime = Date.now()
await next()
const runtime = Date.now() - startTime
console.log(`Calling ${context.method} on service ${context.path} took ${runtime}ms`)
}
import { logger } from '../logger.js'
export const profiler = async (context, next) => {
const startTime = Date.now()
await next()
const runtime = Date.now() - startTime
console.log(`Calling ${context.method} on service ${context.path} took ${runtime}ms`)
}
import { logger } from '../logger.js'
export const profiler = async (context, next) => {
const startTime = Date.now()
await next()
const runtime = Date.now() - startTime
console.log(`Calling ${context.method} on service ${context.path} took ${runtime}ms`)
}
And add it in src/app.ts as an application hook after the logError hook as follows:
import { profiler } from './hooks/profiler'
//...
// Register hooks that run on all service methods
app.hooks({
around: {
all: [logError, profiler]
},
before: {},
after: {},
error: {}
})
import { profiler } from './hooks/profiler'
//...
// Register hooks that run on all service methods
app.hooks({
around: {
all: [logError, profiler]
},
before: {},
after: {},
error: {}
})
import { profiler } from './hooks/profiler.js'
//...
// Register hooks that run on all service methods
app.hooks({
around: {
all: [logError, profiler]
},
before: {},
after: {},
error: {}
})
import { profiler } from './hooks/profiler.js'
//...
// Register hooks that run on all service methods
app.hooks({
around: {
all: [logError, profiler]
},
before: {},
after: {},
error: {}
})