如何在NodeJS中更改响应的状态码？

Question

我正在NodeJS中开发一个API，该API可以使用客户端的请求主体向巴西邮件服务的API发出另一个请求，然后以特定格式将响应发送给客户端。问题是：当我的客户放置的邮政编码中没有可用的交付时，我从邮件API（以及我提供给客户的那个）中获得的状态代码为200。但是我需要状态代码400.我可以在NodeJS中更改状态代码吗？

以下代码：

'use strict';

const soapRequest = require('easy-soap-request');
var convert = require('xml-js');

//Create the POST Method
exports.post = (req, res) => {
    //Define the parameters for the XML
    for (x in req.body.items.length) {
        var width = req.body.items[x].dimensions.width * 100;
        var height = req.body.items[x].dimensions.height * 100;
        var weight = req.body.items[x].dimensions.weight;
        var depth = req.body.items[x].dimensions.depth * 100;
        var quantity = req.body.items[x].quantity;
        var sku = req.body.items[x].sku;
    };
    var sellerZipcode = '05036123';
    var clientZipcode = req.body.zipcode;

    //Define data for the XML
    const xmlUrl = 'http://ws.correios.com.br/calculador/CalcPrecoPrazo.asmx';
    const sampleHeaders = {
    'Content-Type': 'text/xml'
    };

    switch (true) {
        case (height >= weight) && (height >= depth):
            height = height * quantity;
            var lowDim = height;
        case (weight >= height) && (weight >= depth):
            weight = weight * quantity;
            var lowDim = weight;
        case (depth >= weight) && (depth >= height):
            depth = depth * quantity;
            var lowDim = depth;
        };

    // The XML itself
    var xmlFile = '<?xml version="1.0" encoding="utf-8"?>' +
    '<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">' +
    '<soap:Body><CalcPrecoPrazo xmlns="http://tempuri.org/">' +
    '<nCdEmpresa>Cant show</nCdEmpresa>' +
    '<sDsSenha>Cant show</sDsSenha>' +
    '<nCdServico>04138</nCdServico>' +
    '<sCepOrigem>' + sellerZipcode + '</sCepOrigem>' +
    '<sCepDestino>' + clientZipcode + '</sCepDestino>' +
    '<nVlPeso>' + weight + '</nVlPeso>' +
    '<nCdFormato>1</nCdFormato>' +
    '<nVlComprimento>' + depth + '</nVlComprimento>' +
    '<nVlAltura>' + height + '</nVlAltura>' +
    '<nVlLargura>' + width + '</nVlLargura>' +
    '<nVlDiametro>' + lowDim + '</nVlDiametro>' +
    '<sCdMaoPropria>N</sCdMaoPropria>' +
    '<nVlValorDeclarado>0</nVlValorDeclarado>' +
    '<sCdAvisoRecebimento>N</sCdAvisoRecebimento>' +
    '</CalcPrecoPrazo></soap:Body></soap:Envelope>';

    //Send the request and takes the response
    async function makeRequest() {
        const { response } = await soapRequest({ url: xmlUrl, headers: sampleHeaders, xml: xmlFile});
        const { headers, body, statusCode} = response;
        var xml = response.body;
        var str = convert.xml2json(xml, {compact: true, spaces: 4, ignoreDeclaration: true, ignoreInstruction: true, ignoreAttributes: true, ignoreDoctype: true, });
        var json = JSON.parse(str);
        return await json;
    };

    //Show error message if there is one, otherwise, show the expected response
    makeRequest().then(json => {
        var json = json["soap:Envelope"]["soap:Body"]["CalcPrecoPrazoResponse"]["CalcPrecoPrazoResult"]["Servicos"]["cServico"];
        var erro = json["MsgErro"];        

        if (erro.hasOwnProperty("_text")){
            res.status(200).send(erro);
        } else { 

            var valor = json["Valor"]["_text"];
            var prazo = json["PrazoEntrega"]["_text"];
            var codigo = json["Codigo"]["_text"];
            var servico = 'SEDEX';

            var str = '{"packages":[{' +
                                '"items":[{' +
                                    '"sku":"' + sku + '",' +
                                    '"quantity":"' + quantity +
                                '"}],' +
                                '"delivery_options":[{' +
                                    '"id":"' + codigo + '",' +
                                    '"type":"Entrega normal",' +
                                    '"name":"' + servico + '",' +
                                    '"price":"' + valor + '",' +
                                    '"delivery_days":"' + prazo + '"}]' +
                                '}]}';

            var response = JSON.parse(str);
            response.packages[0].delivery_options[0].delivery_days = parseInt(response.packages[0].delivery_options[0].delivery_days);
            response.packages[0].items[0].quantity = parseInt(response.packages[0].items[0].quantity);
            //Response with status 200
            res.status(200).send(response);
        };
    });
}