Question

我用NodeJS / Mongoose创建了一个CRUD，将文件拆分为MVC样式。在下面显示的路由示例中，执行Dim fnt As System.Drawing.Font, size_M As Drawing.Size, size_i As Drawing.Size, size_HTab As Drawing.Size, isMonospace As Boolean Dim ifc = New Drawing.Text.InstalledFontCollection Dim bm As Drawing.Bitmap = New Drawing.Bitmap(640, 64), gr = Drawing.Graphics.FromImage(bm) Dim tf As Windows.Media.Typeface, gtf As Windows.Media.GlyphTypeface = Nothing, ok As Boolean, gtfName = "" For Each item In ifc.Families 'TestContext_WriteTimedLine($"N={item.Name}.") fnt = New Drawing.Font(item.Name, 24.0) Assert.IsNotNull(fnt) tf = New Windows.Media.Typeface(item.Name) Assert.IsNotNull(tf, $"item.Name={item.Name}") size_M = System.Windows.Forms.TextRenderer.MeasureText("M", fnt) size_i = System.Windows.Forms.TextRenderer.MeasureText("i", fnt) size_HTab = System.Windows.Forms.TextRenderer.MeasureText(ChrW(&H2409), fnt) isMonospace = size_M.Width = size_i.Width Assert.AreEqual(size_M.Height, size_i.Height, $"fnt={fnt.Name}") If isMonospace Then gtfName = "-" ok = tf.TryGetGlyphTypeface(gtf) If ok Then Assert.AreEqual(True, ok, $"item.Name={item.Name}") Assert.IsNotNull(gtf, $"item.Name={item.Name}") gtfName = $"{gtf.FamilyNames(Globalization.CultureInfo.CurrentUICulture)}" Assert.AreEqual(True, gtf.CharacterToGlyphMap().ContainsKey(AscW("M")), $"item.Name={item.Name}") Assert.AreEqual(True, gtf.CharacterToGlyphMap().ContainsKey(AscW("i")), $"item.Name={item.Name}") Dim t = 0, nMin = &HFFFF, nMax = 0 For n = 0 To &HFFFF If gtf.CharacterToGlyphMap().ContainsKey(n) Then If n < nMin Then nMin = n If n > nMax Then nMax = n t += 1 End If Next gtfName &= $",[x{nMin:X}-x{nMax:X}]#{t}" ok = gtf.CharacterToGlyphMap().ContainsKey(AscW(ChrW(&H2409))) If ok Then gtfName &= ",U+2409" End If ok = gtf.CharacterToGlyphMap().ContainsKey(AscW(ChrW(&H2026))) If ok Then gtfName &= ",U+2026" End If End If Debug.WriteLine($"{IIf(isMonospace, "*M*", "")} N={fnt.Name}, gtf={gtfName}.") gr.Clear(Drawing.Color.White) gr.DrawString($"Mi{ChrW(&H2409)} {fnt.Name}", fnt, New Drawing.SolidBrush(Drawing.Color.Black), 10, 10) bm.Save($"{fnt.Name}_MiHT.bmp") End If Next例程时，有必要等待其处理，然后将用户重定向到一条路由或另一条路由。我想使用Bluebird等待处理。我需要一些帮助来实现例程。

Index.js -------------------------------------------- ---

retrieveOne

controller.js ------------------------------------------

const myCRUD = require('./api/controllers/controller')

router.post('/login', function(req, res, next) {   

   // HOW TO IMPLEMENT BLUEBIRD HERE?

   // How to wait for the "retrieveOne" process and a then do a "if" test (below)?   
   let ret = myCRUD.retrieveOne({ name: "abc test" }); 


   if(!ret) {
      res.redirect('/success')
   } else {
      res.redirect('/error')
   }
})

注意：我已经在S.O.中找到了一些带有和不带有Bluebird的示例，但是我无法使它正常工作：示例：1，2，3，4，5

Answer 1

您真的不需要使用Bluebird，因为猫鼬可以与本地Promises很好地工作

在您的控制器中：

const mongoose = require('mongoose');
const Schema = require('./schema-user');
const Model = mongoose.model('users', Schema);

const CRUD = {
   retrieveOne: function(query) {
      // findOne() returns a Promise ()
      // https://mongoosejs.com/docs/promises.html
      return Model.findOne(query);
   }
}

module.exports = CRUD;

现在，您可以将路由处理程序设为async函数，而仅await个承诺

const myCRUD = require('./api/controllers/controller')

router.post('/login', async function(req, res, next) { 
   let ret = await myCRUD.retrieveOne({ name: "abc test"}); 
   if(!ret) {
      res.redirect('/success')
   } else {
      res.redirect('/error')
   }
})

Answer 2

使用async和await

const myCRUD = require('./api/controllers/controller')
const Promise = require('bluebird');

router.post('/login', async function(req, res, next) {   

   // HOW TO IMPLEMENT BLUEBIRD HERE?

   // How to wait for the "retrieveOne" process and a then do a "if" test (below)?   
   let ret = await myCRUD.retrieveOne('{ name: "abc test"'); 


   if(!ret) {
      res.redirect('/success')
   } else {
      res.redirect('/error')
   }
})

// controller.js ------------------------------------------

const mongoose = require('mongoose');
const Schema = require('./schema-user');
const Model = mongoose.model('users', Schema);

const CRUD = {
   retrieveOne: function(query) {
      return new Promise((resolve, reject) => {
        Model.findOne(query, function(err, result) {
           if (err) reject(err);
           resolve(result);
        });
      });
   }
}

module.exports = CRUD;

如何等待猫鼬搜索的返回？

2 个答案: