how do I save a collection?

[angrocode]

import { uuidv7 } from 'uuidv7'
import { PersistentCollection, Collection, createFilesystemAdapter, createIndex } from 'signaldb'


const users = new Collection({
  persistence: createFilesystemAdapter('./users.json'),
  indices: [createIndex('id')],
})

users.on('persistence.error', (...argv) => {
  console.log('error:', argv)
})

users.on('added', (...argv) => {
  console.log('added:', argv)
})

users.insert({id: uuidv7(), name: 'qwerty', age: 1})
users.insert({id: uuidv7(), name: 'qwerty', age: 2})
users.insert({id: uuidv7(), name: 'qwerty', age: 3})

how do I save a collection?

[maxnowack]

The save itself is done automatically in the background. Thepersistence.transmitted event is fired after the save is done

[angrocode]

Please run my code and check it.
I'm not creating a file.

[angrocode]

The file is created when adding await setTimeout(1000).
The data is not written to the file.

import { uuidv7 } from 'uuidv7'
import { PersistentCollection, Collection, createFilesystemAdapter, createIndex } from 'signaldb'
import { setTimeout } from 'node:timers/promises'


const users = new Collection({
  persistence: createFilesystemAdapter('./users.json'),
  indices: [createIndex('id')],
})

users.on('persistence.error', (...argv) => {
  console.log('error:', argv)
})

users.on('added', (...argv) => {
  console.log('added:', argv)
})

users.insert({id: uuidv7(), name: 'qwerty', age: 1})
users.insert({id: uuidv7(), name: 'qwerty', age: 2})
users.insert({id: uuidv7(), name: 'qwerty', age: 3})

await setTimeout(1000)
process.exit()

[maxnowack]

The issue here is, that the data was inserted before the persistence was initialized properly (persistence.init event).
I see that this behaviour isn't great in terms of developer experience. I'll try to find a solution for it. The current workaround would be to wait until the persistence.init event was emitted by the collection and modify the data afterwards

[maxnowack]

I've opened #492 for changing the behaviour

[angrocode]

Working version
Run it three times
Get an error: 38e192","name":"qwerty","age":2}]{"id":"018d12ca-812d-70f9-8c0b-7c7b700c40ae","name":"qwerty","age":3}]
Closing the array and inserting after it: 2}]{

import { uuidv7 } from 'uuidv7'
import { PersistentCollection, Collection, createFilesystemAdapter, createIndex } from 'signaldb'
import { setTimeout } from 'node:timers/promises'


const users = new Collection({
  persistence: createFilesystemAdapter('./users.json'),
  indices: [createIndex('id')],
})

users.on('persistence.error', (e) => console.log('error:', e))

let flag = false
users.once('persistence.init', () => flag = true)

users.on('added', (data) => console.log('added:', data))

while (true) {
  await setTimeout(1000)
  if (flag) break
}

users.insert({id: uuidv7(), name: 'qwerty', age: 1})
users.insert({id: uuidv7(), name: 'qwerty', age: 2})
users.insert({id: uuidv7(), name: 'qwerty', age: 3})

const cursor = users.find({})
console.log(cursor.fetch())

await setTimeout(1000)
process.exit()

[maxnowack]

Please try again with version v0.8.3. It should be also no more be necessary to wait until persistence.init is emitted

[angrocode]

v0.8.3
Without while he writes but does not read from the file.
With while writes and reads, but loses some of the records.

[maxnowack]

In which cases are you losing records?