Package Exports

resolve-command

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Readme

📢 resolve-command

Provides a function to handle a command and send the generated event to an event store based on definitions of aggregates and their commands.

Usage

When initializing a command, pass the following arguments:

eventStore Configured eventStore instance
aggregates Array of aggregates

After the command is initialized, you get a function that is used to send an event to the event store. It receives two arguments:

command An object with the following fields:
- aggregateId - unique id of aggregate
- aggregateName - name of aggregate that has to handle command
- type - command type
A command may also have some additional payload.
getJwt Callback for retrieve actual client state stored in verified JWT token.

Example

import commandHandler from 'resolve-command'
import createEsStorage from 'resolve-storage-memory'
import createBusDriver from 'resolve-bus-memory'
import createEventStore from 'resolve-es'

const aggregates = [{
  name: 'User',
  initialState: {},
  eventHandlers: {
    UserCreated: (state, { name, email}) => ({
      ...state,
      name,
      email
    })
  },
  commands: {
    create: (state, { aggregateId, name, email}) => ({
      type: 'UserCreated',
      aggregateId,
      name,
      email
    })
  }
}]

const eventStore = createEventStore({ storage: createEsStorage(), bus: createBusDriver() })

eventStore.onEvent(['UserCreated'], event =>
  console.log('Event emitted', event)
)

const execute = commandHandler({
  eventStore,
  aggregates
})

const command = {
  aggregateId: '1',
  aggregateName: 'User',
  type: 'create',
  name: 'User Name',
  email: 'test@user.com'
}

execute(command).then(event => {
  console.log('Event saved', event);
})