在Scala中创建多维数组 [英] Creating a multidimensional array in scala

问题描述

我正在解析这样的json对象:

I am parsing a json object like this:

val product_array:Option[Any] = scala.util.parsing.json.JSON.parseFull(products_json)

var product_array2 = Array()

product_array match {
case Some(p) => {
for {
  (id, desc) <- p.asInstanceOf[Map[String,Map[String,Any]]]
  (propName, propValue) <- desc
}  product_array2(id) ++ Array(propName->propValue.toString)
}
case None => test = "No products in shopping cart"
}

问题是我正在尝试使用此行创建多维数组:

The problem is that I am trying to create a multidimensional array with this line:

product_array2(id) ++ Array(propName->propValue.toString)

但是它不起作用.如何在for循环中创建多维数组?

But it doesn't work. How can I create a multidimensional array in the for loop?

希望我能澄清一下:

在PHP中将是这样:

product_array2[id][propName]=propValue;

推荐答案

如果要访问该结构，@ lpaul7的答案将告诉您如何操作.如果要更新结构，则需要处理嵌套的不可变Map，或者将结果确实转换为可变结构(尝试对Array进行处理).

If you want to access the structure, the answer of @lpaul7 will tell you how. If you want to update the structure, you either need to deal with the nested immutable Map, or convert the result indeed into a mutable structure (what you tried to do with the Array).

这有点令人讨厌:

import scala.util.parsing.json.JSON._

val json = """{"id": {"age": 33}}"""

val im = parseFull(json) match {
  case Some(m: Map[_, _]) => 
    m.asInstanceOf[Map[String, Any]].collect {
      case (key, value: Map[_, _]) => (key, value.asInstanceOf[Map[String, Any]])
    }
  case _ => Map.empty[String, Map[String, Any]]
}

查询:

im("id")("age")

不变的更新:

val updated = im + ("id" -> (im.getOrElse("id", Map.empty) + ("age" -> 44)))

可变结构(外部和内部结构均使用可变映射):

Mutable structure (using mutable maps both for the outer and inner structure):

import collection.{breakOut, mutable}

val mut: mutable.Map[String, mutable.Map[String, Any]] = 
   im.map { case (key, inner) => key -> mutable.Map(inner.toSeq: _*)} (breakOut)

可变更新:

mut("id")("age") = 55

---

换句话说，您将真正想要一个无噪声的Scala JSON解决方案，例如 Lift的json ， sjson 或

---

In other words, you will really want a noise-free Scala JSON solution, such as the Lift's json, sjson, or Jerkson libraries.

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