另一个CoffeeScript错误 [英] Another CoffeeScript Error
问题描述
嘿,我只是学习CoffeeScript和我继续得到错误。这是我的代码:
Hey, I am Just Learning CoffeeScript and I Keep getting Errors. Here is my code:
Db = require('./lib/mongodb').Db
ObjectID = require('./lib/mongodb').ObjectID
Server = require('./lib/mongodb').Server
class UserDataProvider
constructor = (host,port)->
this.db = new Db( 'test' , new Server(host ,port,{}))
getCollection = (callback) ->
this.db.collection 'data',(error,data)->
if error then callback(error)
else callback(data)
findAll = (callback) ->
this.getCollection (error,data)->
if error then callback error
else
data.find (error, cursor) ->
if error then callback error
else
cursor.toArray (error, results)->
if error then callback error
else callback(null,results)
findById = (id,callback)->
this.getCollection (error, data)->
if error then callback error
else
data.findOne { _id: id} , (error, result)->
if error then callback error
else callback(null, result)
save = (data, callback)->
this.getCollection (error, collection)->
if error then callback error
else
if typeof(data.length) is "undefined"
then data = [data]
collection.insert data ()->
callback null, data
exports.UserDataProvider = UserDataProvider
当我尝试使用
userdataprovider.save(?? BLAH BLAH BLAH ??)//我已经实例化它。
When I try to use userdataprovider.save( ?? BLAH BLAH BLAH ??) // I already instantiated it.
我得到这个错误: p>
I get this error:
TypeError: Object #<UserDataProvider> has no method 'save'
at Object.<anonymous> (/home/akshay/dev/statServer/app.js:8:15)
at param (/usr/local/lib/node/.npm/connect/0.5.10/package/lib/connect/middleware/router.js:146:21)
at param (/usr/local/lib/node/.npm/connect/0.5.10/package/lib/connect/middleware/router.js:157:15)
at pass (/usr/local/lib/node/.npm/connect/0.5.10/package/lib/connect/middleware/router.js:162:10)
at Object.router [as handle] (/usr/local/lib/node/.npm/connect/0.5.10/package/lib/connect/middleware/router.js:168:6)
at next (/usr/local/lib/node/.npm/connect/0.5.10/package/lib/connect/index.js:218:15)
at Object.handle (/usr/local/lib/node/.npm/express/1.0.7/package/lib/express/server.js:65:5)
at next (/usr/local/lib/node/.npm/connect/0.5.10/package/lib/connect/index.js:218:15)
at Server.handle (/usr/local/lib/node/.npm/connect/0.5.10/package/lib/connect/index.js:231:3)
at Server.emit (events.js:45:17)
使用Expressjs和Nodejs with Native MongoDB Driver
If it matters, I am using Expressjs and Nodejs with Native MongoDB Driver
推荐答案
问题是你使用 =
而不是
:
来定义实例级方法。
The problem is that you're using =
instead of :
to define instance-level methods.
CoffeeScript的 class
构造是对象和函数的奇怪混合。类体内的代码立即运行,例如
CoffeeScript's class
construct is an odd hybrid of object and function. Code within the class body runs immediately—for instance,
class UserDataProvider
a = 'foo'
console.log a
打印 foo
。但是当使用对象语法 key:value
时,您定义了原型的属性(除了特殊关键字构造函数
):
prints foo
. But when you use the object syntax key: value
, you define properties of the prototype (except in the case of the special keyword constructor
):
class UserDataProvider
a: 'foo'
(new UserDataProvider).a # 'foo'
这可能看起来很奇怪,但它允许你运行一次静态初始化代码,它可以是有用的,包括只能通过类中定义的方法看到的私有变量:
This might seem odd, but it allows you to run one-time static initialization code which can be useful, including private variables that can only be seen by methods defined within the class:
class UserDataProvider
secretPassword = Math.random()
getHash: -> hash(secretPassword)
长故事:使用:
而不是 =
时定义实例属性。 (对于静态属性, @a = b
和 @a:b
是等价的; > UserDataProvider.a 到 b
。)
Long story short: Use :
instead of =
when defining instance properties. (For static properties, @a = b
and @a: b
are equivalent; both set UserDataProvider.a
to b
.)
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