cakephp functions like Set::combine in Javascript

问题

Are there already some javascript functions that do the same as the cakephp functions Set::combine and Set::classicExtract on client side in the browser? http://book.cakephp.org/2.0/en/core-utility-libraries/set.html

So that I can bring this array:

a = [
   {
        'User' : {
            'id' : 2,
            'group_id' : 1,
            'name' : 'Alfred'
         }
    },
    {
        'User' : {
            'id' : 12,
            'group_id' : 2,
            'name' : 'Albert'
         }
    }
]

with a function like

Set::combine(a, '{n}.User.id', '{n}.User.name') 

into the format

a = {
  2 : 'Alfred',
  12 : 'Albert' 
}

for example. But it's not only for this simple example, I'm really looking for a library or something which can do it in a similar way to cakephp. Thanks a lot in advance!

回答1:

No. Javascript has nothing like this built-in.

Either you make these functions yourself, or you use a library such as Underscore.js which provides a lot of utilities like this.

回答2:

I would love to see a JS equivalent to CakePHP's Hash class, but sadly after an hour of Googling, I cannot find anything... Underscore.js and Sugar.js both have some filtering functions, but neither seem to work on multi-dimensional arrays.

In Cake I often do things like this...

Hash::extract($users, '{n}.User.Posts.{n}.Comments.{n}[published=1]');

If anyone knows a JS library that does this, would be very grateful for the tip.

---

EDIT: I have since found a few options that allow this kind of querying of JSON data (with examples of the syntax they use).

• JSPath
  .automobiles{.maker === "Honda" && .year > 2009}.model

• json:select() (inspired more by CSS selectors)
  .automobiles .maker:val("Honda") .model

• JSONPath (inspired more by XPath)
  $.automobiles[?(@.maker='Honda')].model

I think JSPath looks the nicest, so I'm going to try and integrate it with my AngularJS + CakePHP app.

回答3:

This is fairly easy in pure javascript:

result = {}
a.forEach(function(item) {
    result[item.User.id] = item.User.name;
})

I realize it's only a simple example, but the point is that javascript supports callbacks and first-class functions, and there's simply no need for magic like "{n}.User.name".

来源：https://stackoverflow.com/questions/14004162/cakephp-functions-like-setcombine-in-javascript