memory-adapter

A library that implements the Write Model and Read Model Adapter interface for storing events and projections in memory. Useful for development and testing but not for production, obviously 😛.
Methods
build
build({ entityName }, { eventStore, projectionStore ) 
builds a read-model and write-model adapter
Parameters
attribute
type
description
entityName
string
the name of the entity
eventStore
object
(optional) an object where keys are entityNames and values are arrays of commit objects
projectionStore
object
(optional) an object where keys are entity names and values are projections objects keyed by id
Returns
an object with write model methods and read model methods​
Example
adapter.js
const memoryAdapterBuilder = require('serverless-cqrs.memory-adapter')
module.exports = memoryAdapterBuilder.build({ 
  entityName: 'todo'
})
You can also provide the initial eventStore and/or projectionStore objects (both are optional). This is useful when writing tests.
test.js
const { test } = require('tap')
const { build } = require('serverless-cqrs.memory-adapter')
​
test('loadEvents', async assert => {
  const eventStore = {
    'foo': [
      { entityId: '123', version: 0, events: [ 'a' ] },
      { entityId: '123', version: 1, events: [ 'b', 'c' ]},
      { entityId: '123', version: 3, events: [ 'd', 'e', 'f' ] },
      { entityId: '123', version: 6, events: [ 'g', 'h', 'i' ] },
    ]
  }
  const expected = [ 'd', 'e', 'f', 'g', 'h', 'i' ]
​
  const adapter = build({ entityName: 'foo' }, { eventStore })
  
  const res = await adapter.loadEvents('123', 1)
​
  assert.deepEquals(res, expected, 'returns events after given version')
})
​
test('get', async assert => {
  const projectionStore = {
    foo: {
      '123':{
        id: '123',
        version: 0,
        state: 'foobar',
      }
    }
  }
​
  const expected = {
    id: '123',
    version: 0,
    state: 'foobar',
  }
​
  const adapter = build({ entityName: 'foo' }, { projectionStore })
 
  const res = await adapter.get('123')
​
  assert.deepEquals(res, expected, 'returns exisiting projection from store')
})

Components - Previous

read-model

Next - Components

dynamodb-adapter

Last updated 1 year ago

attribute	type	description
`entityName`	`string`	the name of the entity
`eventStore`	`object`	(optional) an object where keys are `entityNames` and values are arrays of commit objects
`projectionStore`	`object`	(optional) an object where keys are entity names and values are projections objects keyed by `id`