Question

我正在使用mongdb并拥有一个用户数据库。我想允许用户根据用户名在数据库中搜索其他用户。到目前为止，我已经尝试过并且没有成功实现这一目标。

这是我的前端HTML：

<h1>Search Users</h1>

<form class="form-inline" method="POST" action="/users/search">
  <div class="form-group">
    <input type="text" name="user_query" class="form-control" placeholder="Find Users By Username...">
  </div>
  <button type="submit" class="btn btn-primary">Search</button>
</form>

我在app.js中的服务器端代码：

// Seach Page
app.get('/', function(req, res, next){
  res.render('searchusers');
});

// Search Processing
app.post('/users/search', function(req, res, next){
  var query = req.body.user_query;

  var result = db.users.findOne({"username":"user_query"})

  console.log('Searched for user: '+result);
});

我在用于存储用户的数据库中的集合称为＆＃34;用户＆＃34;。每当我致电db.users.findOne({"username":user_query})时，我在提交表格后会收到错误：

TypeError: Cannot read property 'findOne' of undefined
    at /Users/joshuablew/Desktop/MobiusApp/app.js:86:24
    at Layer.handle [as handle_request] (/Users/joshuablew/Desktop/MobiusApp/node_modules/express/lib/router/layer.js:95:5)
    at next (/Users/joshuablew/Desktop/MobiusApp/node_modules/express/lib/router/route.js:137:13)
    at Route.dispatch (/Users/joshuablew/Desktop/MobiusApp/node_modules/express/lib/router/route.js:112:3)
    at Layer.handle [as handle_request] (/Users/joshuablew/Desktop/MobiusApp/node_modules/express/lib/router/layer.js:95:5)
    at /Users/joshuablew/Desktop/MobiusApp/node_modules/express/lib/router/index.js:281:22
    at Function.process_params (/Users/joshuablew/Desktop/MobiusApp/node_modules/express/lib/router/index.js:335:12)
    at next (/Users/joshuablew/Desktop/MobiusApp/node_modules/express/lib/router/index.js:275:10)
    at /Users/joshuablew/Desktop/MobiusApp/app.js:74:3
    at Layer.handle [as handle_request] (/Users/joshuablew/Desktop/MobiusApp/node_modules/express/lib/router/layer.js:95:5)
    at trim_prefix (/Users/joshuablew/Desktop/MobiusApp/node_modules/express/lib/router/index.js:317:13)
    at /Users/joshuablew/Desktop/MobiusApp/node_modules/express/lib/router/index.js:284:7
    at Function.process_params (/Users/joshuablew/Desktop/MobiusApp/node_modules/express/lib/router/index.js:335:12)
    at next (/Users/joshuablew/Desktop/MobiusApp/node_modules/express/lib/router/index.js:275:10)
    at /Users/joshuablew/Desktop/MobiusApp/node_modules/connect-flash/lib/flash.js:21:5
    at Layer.handle [as handle_request] (/Users/joshuablew/Desktop/MobiusApp/node_modules/express/lib/router/layer.js:95:5)
    at trim_prefix (/Users/joshuablew/Desktop/MobiusApp/node_modules/express/lib/router/index.js:317:13)
    at /Users/joshuablew/Desktop/MobiusApp/node_modules/express/lib/router/index.js:284:7
    at Function.process_params (/Users/joshuablew/Desktop/MobiusApp/node_modules/express/lib/router/index.js:335:12)
    at next (/Users/joshuablew/Desktop/MobiusApp/node_modules/express/lib/router/index.js:275:10)
    at /Users/joshuablew/Desktop/MobiusApp/node_modules/express-validator/lib/express_validator.js:355:5
    at Layer.handle [as handle_request] (/Users/joshuablew/Desktop/MobiusApp/node_modules/express/lib/router/layer.js:95:5)

我可以采取哪些不同的方式，以便当用户在表单中搜索用户名时，结果会显示在网页上？感谢。

Answer 1

您应该首先建立与MongoDB的连接。您可以找到例如here的指南。

在findOne函数中，您可以找到用户名为＆＃34; user_query＆＃34;的文档。您必须用正确的名称替换正确的结果。

作为建议，您应该使用user_name而不是user_query来获得更易读的代码。

Answer 2

假设数据库连接设置成功，您可以通过mongo shell检查集合是否存在吗？

一个简单的＆＃34; db.users.find（）＆＃34;或＆＃34;显示集合＆＃34;在shell中将显示用户集合是否存在。如果没有，您将需要通过db.createCollection创建集合（＆＃34; users＆＃34;）

在Mongodb数据库中搜索用户

2 个答案: