是否可以获取scala中方法的参数名称

发布于 2024-10-20 00:52:38 字数 970 浏览 2 评论 0原文

据我所知，我们在Java中无法做到这一点。我们可以在scala中做到这一点吗？

假设有一个方法如下：

def insert(name:String, age:Int) {
    // insert new user
}

scala中是否可以获取参数名称name和age？

更新

我想这样做，因为我想自动绑定方法的参数。

例如，这是一个 Web 应用程序，它的一些操作定义为：

class UsersController extends Controller {
    def create(name: String, age: Int) {
          // insert the user
    }
}

客户端单击创建用户表单的 submit 按钮。 url 将为 /users/create 并发送一些参数。

在服务器端，当我们得到一个名为/users/create的url时，我们会在控制器UsersController中找到一个方法create，找到一个现在。然后我必须获取该方法的参数名称，然后我们才能获取它们的值：

val params = getParamsFromRequest()
val method = findMethodFromUrl("/users/create")
val paramNames = getParamNamesOfMethod(method)
val paramValues = getValues(params, paramNames)

// then invoke
method.invoke(controller, paramValues)

现在，关键是如何获取方法的参数名称？

原文

As far as I know, we can't do this in Java. Can we do this in scala?

Suppose there is a method as following:

def insert(name:String, age:Int) {
    // insert new user
}

Is it possible to get the parameter names name and age in scala?

UPDATE

I want to do this, because I want to bind the parameters of methods automaticlly.

For example, this is a web app, it has some actions defined as:

class UsersController extends Controller {
    def create(name: String, age: Int) {
          // insert the user
    }
}

A client clicked the submit button of a creating-user form. The url will be /users/create and with some parameters sending.

On the server side, when we get a url named /users/create, we will find a method create in the controller UsersController, found one now. Then I have to get the parameter names of that method, then we can get the values of them:

val params = getParamsFromRequest()
val method = findMethodFromUrl("/users/create")
val paramNames = getParamNamesOfMethod(method)
val paramValues = getValues(params, paramNames)

// then invoke
method.invoke(controller, paramValues)

Now, the key is how to get the parameter names of a method?

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独木成林 2024-10-27 00:52:38

它仍然非常正在进行中，但你应该能够to：

import scalaj.reflect._
for {
  clazz <- Mirror.ofClass[UsersController].toSeq
  method <- clazz.allDefs.find(_.name == "insert").toSeq
  params <- method.flatParams
} yield params

对 toSeqs 感到抱歉，它们是为了在 for-compression 中使用 Option 解决已知问题。

请不要把它逼得太紧，它还很年轻而且很脆弱。我当然还没有到接受错误报告的阶段:)

更新

嗯...我知道我说过我不接受错误报告，但是这个似乎非常有用，以至于反正我已经把它推到github上了。

要动态地完成这项工作（从 String 类名）：

import scalaj.reflect._
for {
  clazz <- Option(Class forName "x.y.UsersController")
  mirror <- Mirror.ofClass(clazz).toSeq
  method <- mirror.allDefs.find(_.name == "insert").toSeq
  params <- method.flatParams
} yield params

It's still very much a work in progress, but you should be able to:

import scalaj.reflect._
for {
  clazz <- Mirror.ofClass[UsersController].toSeq
  method <- clazz.allDefs.find(_.name == "insert").toSeq
  params <- method.flatParams
} yield params

Sorry about the toSeqs, they're to work around a known issue using Options in a for-comprehension.

Please don't push it too hard, it's still very young and fragile. I'm certainly not at the stage yet where I'd accept bug reports :)

UPDATE

Well... I know that I said I'm not accepting bug reports, but this one seemed so useful that I've pushed it up to github anyway.

To do the job dynamically (from a String class name):

import scalaj.reflect._
for {
  clazz <- Option(Class forName "x.y.UsersController")
  mirror <- Mirror.ofClass(clazz).toSeq
  method <- mirror.allDefs.find(_.name == "insert").toSeq
  params <- method.flatParams
} yield params

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