Package Exports

resolve-readmodel-memory

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Readme

resolve-readmodel-memory

This package is a resolve-query adapter for storing a read model in memory. The adapter is based on key/value ES6 Map interface and does not have binary dependencies.

The store interface is implemented using the resolve-readmodel-memory adapter and provides segregated read and write access:

Read access is used to retrieve data from a store (for example, by a graphql resolver). The package provides the hget(key, field) asynchronous method to get the value associated with the field from the hash stored at the key.
Projection functions use Write access to update data. The following asynchronous methods are available:
- hset(key, field, value) - sets the value associated with the field in the hash stored at key;
- del(key) - deletes the hash stored at the key. Does nothing if the key does not exist.

Usage

import createMemoryAdapter from 'resolve-readmodel-memory';
import { createReadModel } from 'resolve-query';

const adapter = createMemoryAdapter();

const testEventStore = {
    subscribeByEventType: (_, handler) => Promise.resolve(
        handler({ type: 'TestEvent', text: 'One' }),
        handler({ type: 'TestEvent', text: 'Two' })
    )
};

const executeReadModel = createReadModel(
    eventStore: testEventStore,
    adapter,
    projection: {
        Init: async (store) => {
            await store.hset('Test', 'myField', { changeCount: 0, text: 'Initial' })
        },
        TestEvent: async (store, event) => {
            const value = await store.hget('Test', 'myField');

            const newValue = { 
                changeCount: value.changeCount + 1,
                text: event.text
            };
            await store.hset('Test', 'myField', newValue);
        }
    }
)

const store = await executeReadModel();
const value = store.hget('Test', 'myField');
console.log(value)