@nestjs/schematics/dist/lib/upgrade/steps/nats.step.js

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

import { isImportDeclaration, isStringLiteral } from 'typescript';
import { addPackageJsonDependency, getPackageJsonDependency, NodeDependencyType, } from '../../../utils/dependencies.utils.js';
import { applyEdits, collectSourceFiles, getSourceRoots, parseSource, quoteOf, removePackageJsonDependency, } from '../upgrade.utils.js';
const NATS_TRANSPORT_PACKAGE = '@nats-io/transport-node';
const NATS_CORE_PACKAGE = '@nats-io/nats-core';
const NATS_V3 = '^3.0.0';
export function migrateNats(report) {
    return (tree) => {
        if (!getPackageJsonDependency(tree, '@nestjs/microservices')) {
            return tree;
        }
        const legacyDependency = getPackageJsonDependency(tree, 'nats');
        let usesNats = !!legacyDependency;
        let importsRewritten = false;
        let customDeserializer = false;
        for (const path of collectSourceFiles(tree, getSourceRoots(tree))) {
            const content = tree.read(path).toString('utf-8');
            if (!/\bnats\b/i.test(content)) {
                continue;
            }
            const usesTransport = /Transport\.NATS\b/.test(content);
            const source = parseSource(path, content);
            const edits = [];
            for (const statement of source.statements) {
                if (isImportDeclaration(statement) &&
                    isStringLiteral(statement.moduleSpecifier) &&
                    statement.moduleSpecifier.text === 'nats') {
                    const quote = quoteOf(statement.moduleSpecifier, source);
                    edits.push({
                        start: statement.moduleSpecifier.getStart(source),
                        end: statement.moduleSpecifier.getEnd(),
                        text: `${quote}${NATS_CORE_PACKAGE}${quote}`,
                    });
                }
            }
            if (edits.length > 0) {
                importsRewritten = true;
                tree.overwrite(path, applyEdits(content, edits));
                report.change(`${path}: rewrote "nats" imports to "${NATS_CORE_PACKAGE}"`);
            }
            if (usesTransport || edits.length > 0) {
                usesNats = true;
            }
            if (usesTransport && /\b(de)?serializer\s*:/.test(content)) {
                customDeserializer = true;
            }
        }
        if (!usesNats) {
            return tree;
        }
        const dependencyType = legacyDependency?.type ?? NodeDependencyType.Default;
        if (legacyDependency) {
            removePackageJsonDependency(tree, 'nats');
            report.change('Removed the legacy "nats" package from package.json');
        }
        if (!getPackageJsonDependency(tree, NATS_TRANSPORT_PACKAGE)) {
            addPackageJsonDependency(tree, {
                type: dependencyType,
                name: NATS_TRANSPORT_PACKAGE,
                version: NATS_V3,
            });
            report.change(`Added "${NATS_TRANSPORT_PACKAGE}@${NATS_V3}" (NATS v3 driver used by @nestjs/microservices v12)`);
        }
        if (importsRewritten &&
            !getPackageJsonDependency(tree, NATS_CORE_PACKAGE)) {
            addPackageJsonDependency(tree, {
                type: dependencyType,
                name: NATS_CORE_PACKAGE,
                version: NATS_V3,
            });
            report.change(`Added "${NATS_CORE_PACKAGE}@${NATS_V3}"`);
        }
        if (importsRewritten) {
            report.warn(`Review the symbols you import from "${NATS_CORE_PACKAGE}": NATS v3 dropped the "StringCodec"/"JSONCodec" helpers and reorganised connection types. "headers()" is still available there.`);
        }
        if (customDeserializer) {
            report.warn('NATS transport: Nest 12 serializes NATS packets as JSON strings and custom deserializers now receive the full NATS message instead of a raw "Uint8Array" — read the payload with "msg.json()" instead of decoding bytes manually.');
        }
        else {
            report.note('NATS transport: Nest 12 serializes packets as JSON strings; if you add custom (de)serializers, they receive the full NATS message ("msg.json()").');
        }
        return tree;
    };
}