nestjs-event-sourcing-lib/dist/core/projection.js

A comprehensive Event Sourcing and CQRS library for NestJS applications

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.Projection = void 0;
/**
 * Base class for projections (read models) in CQRS system
 */
class Projection {
    constructor(id) {
        /**
         * Last processed event version
         */
        this.lastEventVersion = 0;
        this.id = id;
        this.lastUpdated = new Date();
    }
    getId() {
        return this.id;
    }
    getLastEventVersion() {
        return this.lastEventVersion;
    }
    getLastUpdated() {
        return this.lastUpdated;
    }
    /**
     * Updates metadata after event processing
     */
    updateMetadata(eventVersion) {
        this.lastUpdated = new Date();
        if (eventVersion !== undefined) {
            this.lastEventVersion = eventVersion;
        }
    }
    /**
     * Checks if projection supports given event type
     */
    supportsEvent(event) {
        return true;
    }
    /**
     * Serializes projection to JSON
     */
    toJSON() {
        return {
            id: this.id,
            lastEventVersion: this.lastEventVersion,
            lastUpdated: this.lastUpdated,
            ...this.getProjectionData(),
        };
    }
    /**
     * Gets projection data for serialization
     */
    getProjectionData() {
        const { id, lastEventVersion, lastUpdated, ...data } = this;
        return data;
    }
    /**
     * Restores projection from JSON
     */
    static fromJSON(json) {
        const { id, lastEventVersion, lastUpdated, ...data } = json;
        const projection = new this(id);
        projection.lastEventVersion = lastEventVersion;
        projection.lastUpdated = new Date(lastUpdated);
        Object.assign(projection, data);
        return projection;
    }
    /**
     * Resets projection to initial state
     */
    reset() {
        this.lastEventVersion = 0;
        this.lastUpdated = new Date();
        this.resetProjectionData();
    }
    /**
     * Resets projection data (should be overridden in projection)
     */
    resetProjectionData() {
        // Default implementation does nothing
    }
}
exports.Projection = Projection;
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