使用Underscorejs从json提取值

Question

I have a json from which I need to filter the objects whose name value matches the passed input and then pluck the href value from the corresponding links object having the ref value of self . I am attaching the code snippet as well as my approach of filtering. I am using Underscore.js .

var jsonObj = [
{
  "links": [
    {
      "rel": "self",
      "href": "http://hostname:port/state/644444",
      "variables": [],
      "variableNames": [],
      "templated": false
    },
    {
      "rel": "city",
      "href": "http://hostname:port/city/6184",
      "variables": [],
      "variableNames": [],
      "templated": false
    }
  ],
  "stateId": 65986,
  "countyId": 6184,
  "name": "AAATest",
  "population": 20000,
  "location": "SFS CSR"
},
{
  "links": [
    {
      "rel": "self",
      "href": "http://hostname:port/state/65987",
      "variables": [],
      "variableNames": [],
      "templated": false
    },
    {
      "rel": "city",
      "href": "http://hostname:port/city/6184",
      "variables": [],
      "variableNames": [],
      "templated": false
    }
  ],
  "stateId": 65987,
  "countyId": 6184,
  "name": "2k8std511",
  "population": 20000,
  "location": "SFS CSR"
  }
]

var keywords='2k8std511';

var filtered = _.filter(jsonObj, function (item) {
                return (_.contains('2k8std511', item['name']));
            });
console.log(_.chain(jsonObj)
 .pluck("links")
 .flatten()
 .value());

Please let me know how to filter based on the given keyword:

Example input: AAATest Expected output: [href:' http://hostname:port/state/644444 ']

Regards, Pradeep

Answer 1

You can do this with plain JavaScript:

var result = jsonObj.filter(function(obj) {
  return obj.name === 'AAATest'
}).reduce(function(acc, obj) {
  var links = obj.links.filter(function(link) {
    return link.rel === 'self'
  }).map(function(link) {
    return link.href
  })
  return acc.concat(links)
},[])

console.log(result) //=> ["http://hostname:port/state/644444"]

Answer 2

Underscore solution:

 var jsonObj = [{ "links": [{ "rel": "self", "href": "http://hostname:port/state/644444", "variables": [], "variableNames": [], "templated": false }, { "rel": "city", "href": "http://hostname:port/city/6184", "variables": [], "variableNames": [], "templated": false }], "stateId": 65986, "countyId": 6184, "name": "AAATest", "population": 20000, "location": "SFS CSR" }, { "links": [{ "rel": "self", "href": "http://hostname:port/state/65987", "variables": [], "variableNames": [], "templated": false }, { "rel": "city", "href": "http://hostname:port/city/6184", "variables": [], "variableNames": [], "templated": false }], "stateId": 65987, "countyId": 6184, "name": "2k8std511", "population": 20000, "location": "SFS CSR" }] var filtername = 'AAATest'; var answer = _.chain(jsonObj) .filter(function(obj) { return obj.name === filtername; }) .map(function(obj) { return obj.links }) .first() .filter(function(obj) { return obj.rel === 'self' }) .map(function(obj) { return obj.href }) .value(); console.log(answer); 

 <script src="http://underscorejs.org/underscore-min.js"></script> 

Answer 3

Another version using underscore:

var result = _.chain(jsonObj)
    .where({ name: 'AAATest' })
    .pluck('links')
    .flatten()
    .where({ rel: 'self'})
    .pluck('href')
    .value();