Batch-data-loader
Simple data loader for batch processing. I wrote it just for fun . Inspired by GraphQL dataloader.
The source is yours, you can freely modify and play with it. Have fun!
Example
names.includes(user.name))
}
const userLoader = new DataLoader(async (keys) => {
console.log('Fetch', keys)
const results = fetchUsersByName(keys)
return keys.map((key) => results.find((user) => user.name === key))
})
userLoader.load('John').then(console.log).catch(console.erro r)
userLoader.load('Jane').then(console.log).catch(console.erro r)
userLoader.load('John').then(console.log).catch(console.erro r)
setTimeout(() => {
userLoader.load('unknown').then(console.log).catch(console.e rror)
userLoader.load('Simon').then(console.log).catch(console.err or)
}, 1000)
/*
Results :
Fetch [ 'John', 'Jane' ]
{ name: 'John', age: 30 }
{ name: 'Jane', age: 27 }
{ name: 'John', age: 30 }
Fetch [ 'unknown', 'Simon' ]
undefined
{ name: 'Simon', age: 5 }
*/">import { DataLoader } from '../dist/DataLoader.js'
const users = [
{
name: 'John',
age: 30
},
{
name: 'Jane',
age: 27
},
{
name: 'Simon',
age: 5
}
]
function fetchUsersByName(names) {
return users.filter((user) => names.includes(user.name))
}
const userLoader = new DataLoader(async (keys) => {
console.log('Fetch', keys)
const results = fetchUsersByName(keys)
return keys.map((key) => results.find((user) => user.name === key))
})
userLoader.load('John').then(console.log).catch(console.error)
userLoader.load('Jane').then(console.log).catch(console.error)
userLoader.load('John').then(console.log).catch(console.error)
setTimeout(() => {
userLoader.load('unknown').then(console.log).catch(console.error)
userLoader.load('Simon').then(console.log).catch(console.error)
}, 1000)
/*
Results :
Fetch [ 'John', 'Jane' ]
{ name: 'John', age: 30 }
{ name: 'Jane', age: 27 }
{ name: 'John', age: 30 }
Fetch [ 'unknown', 'Simon' ]
undefined
{ name: 'Simon', age: 5 }
*/
const users = [
{
name: 'John',
age: 30
},
{
name: 'Jane',
age: 27
},
{
name: 'Simon',
age: 5
}
]
function fetchUsersByName(names) {
return users.filter((user) => names.includes(user.name))
}
const userLoader = new DataLoader(async (keys) => {
console.log('Fetch', keys)
const results = fetchUsersByName(keys)
return keys.map((key) => results.find((user) => user.name === key))
})
userLoader.load('John').then(console.log).catch(console.error)
userLoader.load('Jane').then(console.log).catch(console.error)
userLoader.load('John').then(console.log).catch(console.error)
setTimeout(() => {
userLoader.load('unknown').then(console.log).catch(console.error)
userLoader.load('Simon').then(console.log).catch(console.error)
}, 1000)
/*
Results :
Fetch [ 'John', 'Jane' ]
{ name: 'John', age: 30 }
{ name: 'Jane', age: 27 }
{ name: 'John', age: 30 }
Fetch [ 'unknown', 'Simon' ]
undefined
{ name: 'Simon', age: 5 }
*/