Lodash group by multiple properties if property value is true

Question

I have an array of vehicles that need to be grouped by make and model, only if the 'selected' property is true. The resulting object should contain properties for make model and count. Using lodash, how can I organize the vehicle objects into the desired result objects. I'm able to get the vehicle objects grouped by makeCode but I'm not sure how to group by more than one property.

group by make code works

      var vehicles = _.groupBy(response.vehicleTypes, function(item)
      {
        return item.makeCode; // how to group by model code as well
      });

initial vehicles

{
    id: 1, 
    selected: true, 
    makeCode: "Make-A", 
    modelCode: "Model-a", 
    trimCode: "trim-a", 
    yearCode: "2012"
},
{
    id: 2, 
    selected: false, 
    makeCode: "Make-A", 
    modelCode: "Model-a", 
    trimCode: "trim-a", 
    yearCode: "2013"
},
{
    id: 3, 
    selected: true, 
    makeCode: "Make-B", 
    modelCode: "Model-c", 
    trimCode: "trim-a", 
    yearCode: "2014"
},
{
    id: 25, 
    selected: true, 
    makeCode: "Make-C", 
    modelCode: "Model-b", 
    trimCode: "trim-b", 
    yearCode: "2012"
},
{
    id: 26, 
    selected: true, 
    makeCode: "Make-C", 
    modelCode: "Model-b", 
    trimCode: "trim-a", 
    yearCode: "2013"
}

result object

{
    Make-A: {
        Model-a: {
            count: 1
        }
    }
},

{
    Make-B: {
        Model-c: {
            count: 1
        }
    }
},
{
    Make-C: {
        Model-b: {
            count: 2
        }
    }
}

Answer 1

I am not sure if this will solve Your problem, but in group_by You can add custom logic which allow You to create composite key.

Remember that SEPERATOR value should be defined accordingly to data source You work with, if "--" characters occur in model or type You should not used them as it will not allow You to reverse the process of grouping.

const SEPERATOR = "--";
_.chain(data).filter((item) => item.selected).groupBy((item)=>`${item.model}${SEPERATOR}${item.type}`).value();

Answer 2

Since you're already using lodash, you can take advantage of the _.filter function. This will return only the items where selected is true.

var selectedVehicles = _.filter(response.vehicleTypes, 'selected');

Now that you have the selectedVehicles array, you can use your original code for grouping by the makeCode .

selectedVehicles = _.groupBy(selectedVehicles, function(item) {
  return item.makeCode;
});

This returns an object, so we will need to iterate through those keys, and perform our second groupBy

_.forEach(selectedVehicles, function(value, key) {
  selectedVehicles[key] = _.groupBy(selectedVehicles[key], function(item) {
    return item.modelCode;
  });
});

From this you will have an object of the form. I'll leave it to you to get the count from each array.

{ 'Make-A': { 'Model-a': [ ... ] },
  'Make-B': { 'Model-c': [ ... ] },
  'Make-C': { 'Model-b': [ ..., ... ] } }

Answer 3

Following code works if you focus on result:

in my case, Brand and Item Code are properties

const products = _.groupBy(this.productsTable.data, (item) => {
    return [item['Brand'], item['Item Code']];
});

Answer 4

You can use Array.prototype.reduce() , and do it in one loop O(n):

 var arr = [{"id":1,"selected":true,"makeCode":"Make-A","modelCode":"Model-a","trimCode":"trim-a","yearCode":"2012"},{"id":2,"selected":false,"makeCode":"Make-A","modelCode":"Model-a","trimCode":"trim-a","yearCode":"2013"},{"id":3,"selected":true,"makeCode":"Make-B","modelCode":"Model-c","trimCode":"trim-a","yearCode":"2014"},{"id":25,"selected":true,"makeCode":"Make-C","modelCode":"Model-b","trimCode":"trim-b","yearCode":"2012"},{"id":26,"selected":true,"makeCode":"Make-C","modelCode":"Model-b","trimCode":"trim-a","yearCode":"2013"},{"id":29,"selected":false,"makeCode":"Make-A","modelCode":"Model-g","trimCode":"trim-a","yearCode":"2013"},{"id":2,"selected":true,"makeCode":"Make-A","modelCode":"Model-h","trimCode":"trim-a","yearCode":"2013"}]; var result = arr.reduce(function(map, obj) { if(!obj.selected) { return map; } var makeCode = map[obj.makeCode] = map[obj.makeCode] || {}; var modelCode = makeCode[obj.modelCode] = makeCode[obj.modelCode] || { count: 0 }; modelCode.count++; return map; }, Object.create(null)); console.log(result);

A more readable, and modern version using destructuring:

 const arr = [{"id":1,"selected":true,"makeCode":"Make-A","modelCode":"Model-a","trimCode":"trim-a","yearCode":"2012"},{"id":2,"selected":false,"makeCode":"Make-A","modelCode":"Model-a","trimCode":"trim-a","yearCode":"2013"},{"id":3,"selected":true,"makeCode":"Make-B","modelCode":"Model-c","trimCode":"trim-a","yearCode":"2014"},{"id":25,"selected":true,"makeCode":"Make-C","modelCode":"Model-b","trimCode":"trim-b","yearCode":"2012"},{"id":26,"selected":true,"makeCode":"Make-C","modelCode":"Model-b","trimCode":"trim-a","yearCode":"2013"},{"id":29,"selected":false,"makeCode":"Make-A","modelCode":"Model-g","trimCode":"trim-a","yearCode":"2013"},{"id":2,"selected":true,"makeCode":"Make-A","modelCode":"Model-h","trimCode":"trim-a","yearCode":"2013"}]; const result = arr.reduce((acc, { selected, makeCode, modelCode }) => { if(!selected) return acc; if(!acc[makeCode]) acc[makeCode] = {}; const make = acc[makeCode]; if(!make[modelCode]) make[modelCode] = { count: 0 }; make[modelCode].count++; return acc; }, Object.create(null)); console.log(result);

Answer 5

 const result = _.chain(vehicles) .filter('selected') .groupBy('makeCode') .mapValues(values => _.chain(values) .groupBy('modelCode') .mapValues(_.size) .value() ) .value()

Answer 6

 const multiGroupBy = (array, group, ...restGroups) => { if(!group) { return array; } const currGrouping = _.groupBy(array, group); if(!restGroups.length) { return currGrouping; } return _.transform(currGrouping, (result, value, key) => { result[key] = multiGroupBy(value, ...restGroups); }, {}); }; console.log(multiGroupBy([{x:1,y:1,z:1},{x:1,y:2,z:1},{x:2,y:1,z:1},{x:2,y:2,z:1},{x:1,y:1,z:2},{x:1,y:2,z:2},{x:2,y:1,z:2},{x:2,y:2,z:2}],'x','y'));

 <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.min.js"></script>

or if you prefer old syntax

 function multiGroupBy(array, group) { if(!group) { return array; } var currGrouping = _.groupBy(array, group); var restGroups = Array.prototype.slice.call(arguments); restGroups.splice(0,2); if(!restGroups.length) { return currGrouping; } return _.transform(currGrouping, function(result, value, key) { result[key] = multiGroupBy.apply(null, [value].concat(restGroups)); }, {}); } console.log(multiGroupBy([{x:1,y:1,z:1},{x:1,y:2,z:1},{x:2,y:1,z:1},{x:2,y:2,z:1},{x:1,y:1,z:2},{x:1,y:2,z:2},{x:2,y:1,z:2},{x:2,y:2,z:2}],'x','y'));

 <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.min.js"></script>

Answer 7

Grouping and filtering an object or array without LODASH on pure JS:

 // Группировка и фильтрация объекта или массива без LODASH на чистом JS: let k = "HUID", // group by; input = [ {HUID:11,test:1}, {HUID:11,test:111}, {HUID:'eeeeeeeeeeee',test:11111}, {HUID:22,test:2}, {HUID:33,test:3} ], result = input.reduce((map, obj) => { //if(!obj.selected) { return map; } let makeCode = (map[obj[k]] = map[obj[k]] || {}); // var modelCode = makeCode[obj.HUID] = makeCode[obj.HUID] || { count: 0 }; let l = map[obj[k]], m = Object.keys(l).length; l[m] = { ...obj }; return map; }, {} ); console.log(result);

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Answer 8

You don't need to reiterate all the array object. with loadash, you can make simple as below:

_.mapValues(_.groupBy(object, 'yourKeys'))

Answer 9

export function groupByLodash(results: myType[]) {
  return mapValues(
    groupBy(results, 'property.to.group'),
    (o: myType) => groupBy(o, 'second.property.to.group'),
  );
}