How to break up an object with a string of values

问题:

I was working on a solution to another question posed, and I came up with a solution, but I'm convinced that there's a more elegant way to do it. Let's say that you have an object where all of the values are a string of values separate by commas, like this:

{ "action" : "goto,goto", "target" : "http://www.google.com,http://www.cnn.com" }

But, you'd like to separate the values and break up the object into an array of objects, like this:

[
    { "action" : "goto", "target" : "http://www.google.com" },
    { "action" : "goto", "target" : "http://www.cnn.com" }
]

Here's what my solution was:

var actions = obj.action.split(',');
var targets = obj.target.split(',');

// combined the actions and targets arrays
var combinedData = _.zip(actions, targets);

// go through the combinedData array and create an object with the correct keys
var commandList = _.map(combinedData, function(value) { 
    return _.object(["action", "target"], value)
});

This does what I want and doesn't look terrible, but is there a slicker way of accomplishing this?

回答1:

Functional style is great. Here's a more direct approach.

var newObjects = [];
for(var k in o) {
    var vals = o[k].split(',');
    for(var i = 0, len = vals.length; i < len; i++) {
        newObjects[i] = newObjects[i] || {};
        newObjects[i][k] = vals[i];
    }
}

I wouldn't worry too much about the implementation until you come up with a nice, compact, semantic name for this operation. Any ideas?

回答2:

So, I did a little refactoring of my code to create a more functional and cleaner looking answer:

var obj = { "action" : "goto,goto", "target" : "http://www.google.com,http://www.cnn.com" }

// separate and split the values form the object
function separate(obj) { 
    return _.map( _.values( obj ), function(value) {
        return value.split(',');
    });
}
// returns [[ "goto", "goto"], ["http://www.google.com", "http://www.cnn.com"]]

// call separate and recombine the values with zip
function separateAndRecombine(obj) {
    return _.zip.apply(_, separate(obj));
}
// returns [[ "goto", "http://www.google.com"], ["goto", "http://www.cnn.com"]]

// accept an object that has properties with a string of values
// separated by commas, and separate the values to create an array of objects
function unwind(obj) {
    return _.map( separateAndRecombine(obj), function(value) { 
            return _.object(_.keys(obj), value)
    });
};
/* returns:
    [{ "action" : "goto", "target" : "http://www.google.com" },
    { "action" : "goto", "target" : "http://www.cnn.com" }] */

Now, unwind() will take an object with any number of properties or values and 'unwind' all of the existing properties.