bun-ws-router/dist/zod/publish.js

Lightweight client/server WebSocket router for Bun with type-safe Zod/Valibot validation.

// SPDX-FileCopyrightText: 2025-present Kriasoft
// SPDX-License-Identifier: MIT
import { z } from "zod";
/**
 * Validates a message against its schema and publishes it to a WebSocket topic.
 *
 * PURPOSE: Ensures all published messages conform to their schemas, preventing
 * runtime errors for subscribers expecting specific message formats.
 *
 * FLOW: Extract type → Construct message → Validate → Publish (or log error)
 *
 * @param ws - The ServerWebSocket instance to publish from
 * @param topic - The topic to publish to (subscribers will receive the message)
 * @param schema - The Zod schema to validate the message against
 * @param payload - The payload to include in the message (type inferred from schema)
 * @param metaOrOpts - Optional metadata or options object with origin tracking
 * @returns True if message was validated and published successfully
 */
export function publish(ws, topic, schema, payload, metaOrOpts) {
    try {
        // Extract the message type from the schema
        // ASSUMES: Schema was created by messageSchema() which guarantees type.value exists
        const messageType = schema.shape.type.value;
        // Build meta with timestamp (producer time for UI display)
        const baseMeta = { timestamp: Date.now() };
        // Handle origin option for sender tracking
        let meta;
        if (metaOrOpts && "origin" in metaOrOpts) {
            const { origin, key = "senderId", ...rest } = metaOrOpts;
            // Only inject if ws.data[origin] is defined and not null (no-op otherwise)
            if (origin && ws.data[origin] !== undefined && ws.data[origin] !== null) {
                meta = { ...baseMeta, ...rest, [key]: ws.data[origin] };
            }
            else {
                meta = { ...baseMeta, ...rest };
            }
        }
        else {
            meta = { ...baseMeta, ...metaOrOpts };
        }
        // Create the message object with the required structure
        // NOTE: timestamp is auto-populated (producer time); clientId is NEVER injected
        const message = {
            type: messageType,
            meta,
            ...(payload !== undefined && { payload }), // Omit payload key if undefined
        };
        // Validate the constructed message against the schema
        // CRITICAL: Prevents malformed messages from reaching subscribers
        const validationResult = schema.safeParse(message);
        if (!validationResult.success) {
            console.error(`[ws] Failed to publish message of type "${messageType}" to topic "${topic}": Validation error`, validationResult.error.issues);
            return false;
        }
        // Publish the validated message to the topic
        // NOTE: Uses Bun's native PubSub - message is sent to all topic subscribers
        ws.publish(topic, JSON.stringify(validationResult.data));
        return true;
    }
    catch (error) {
        // Catches schema extraction errors or publish failures
        console.error(`[ws] Error publishing message to topic "${topic}":`, error);
        return false;
    }
}
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