@nestjs/microservices/serializers/kafka-request.serializer.js

Nest - modern, fast, powerful node.js web framework (@microservices)

import { MaxKafkaHeadersExceededException } from '../errors/max-kafka-headers-exceeded.exception.js';
import { isNil, isObject, isPlainObject, isString, isUndefined, } from '@nestjs/common/internal';
// kafkajs encodes each value of the headers (a repeated header has several)
// as a header of its own, at about 1 kB apiece
const MAX_HEADER_VALUES = 10_000;
/**
 * @publicApi
 */
export class KafkaRequestSerializer {
    serialize(value) {
        const isNotKafkaMessage = isNil(value) ||
            !isObject(value) ||
            (!('key' in value) && !('value' in value));
        // Serialize a copy, headers included: ClientKafka and ServerKafka write
        // correlation metadata into the returned headers, and the caller's record
        // may be frozen, reused or sent concurrently.
        const record = (isNotKafkaMessage ? { value } : value);
        // Spreading a string or an array (as an echo handler may return them)
        // would turn each of its characters or items into a header
        const headers = isObject(record.headers) && !Array.isArray(record.headers)
            ? record.headers
            : {};
        let headerValues = 0;
        for (const headerValue of Object.values(headers)) {
            headerValues += Array.isArray(headerValue) ? headerValue.length : 1;
        }
        if (headerValues > MAX_HEADER_VALUES) {
            throw new MaxKafkaHeadersExceededException(headerValues, MAX_HEADER_VALUES);
        }
        const request = { ...record, headers: { ...headers } };
        request.value = this.encode(request.value);
        if (!isNil(request.key)) {
            request.key = this.encode(request.key);
        }
        return request;
    }
    encode(value) {
        const isObjectOrArray = !isNil(value) && !isString(value) && !Buffer.isBuffer(value);
        if (isObjectOrArray) {
            return isPlainObject(value) ||
                Array.isArray(value) ||
                value.toString == Object.prototype.toString // Prevent default [object Object] behavior
                ? JSON.stringify(value)
                : value.toString();
        }
        else if (isUndefined(value)) {
            return null;
        }
        return value;
    }
}