Filtering Nested Array with Lodash/Javascript

Question

I have the following object array:

var sizeList = [
    { id: 1, title:"Test1",
        type:[{name:"Big", present:false}, {name:"Small", present:true}, {name:"Medium", present:false}]
    },

    { id: 2,title:"Test2",
        type:[{name:"Big", present:false}, {name:"Small", present:true}, {name:"Medium", present:false}]
    },
    { id: 3,title:"Test3",
        type:[{name:"Big", present:false}, {name:"Small", present:true}, {name:"Medium", present:true}]
    }
  ]

I want to filter this list where Medium is True. I currently have this set up.

var specificSizes = _.filter(sizeList.type, { 'name': 'Medium', 'present': true })

This keeps returning an empty array. I also tried this:

       specificSizes = _.filter(sizeList.type, function (type) {
          return _.some(type, {'name': 'Medium', 'present':true})
        });

Answer 1

With lodash, you could wrap the condition in the same structure for the test, as the original object.

_.filter(sizeList, { type: [{ name: 'Medium', present: true }] })

var sizeList = [{ id: 1, title: "Test1", type: [{ name: "Big", present: false }, { name: "Small", present: true }, { name: "Medium", present: false }] }, { id: 2, title: "Test2", type: [{ name: "Big", present: false }, { name: "Small", present: true }, { name: "Medium", present: false }] }, { id: 3, title: "Test3", type: [{ name: "Big", present: false }, { name: "Small", present: true }, { name: "Medium", present: true }] }],      
    result = _.filter(sizeList, { type: [{ name: 'Medium', present: true }] });

console.log(result);

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<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.15.0/lodash.min.js"></script>

In plain Javascript, you could use Array#filter for the outer array and check with Array#some if one condition met.

var sizeList = [{ id: 1, title: "Test1", type: [{ name: "Big", present: false }, { name: "Small", present: true }, { name: "Medium", present: false }] }, { id: 2, title: "Test2", type: [{ name: "Big", present: false }, { name: "Small", present: true }, { name: "Medium", present: false }] }, { id: 3, title: "Test3", type: [{ name: "Big", present: false }, { name: "Small", present: true }, { name: "Medium", present: true }] }],      
    result = sizeList.filter(function (a) {
        return a.type.some(function (b) {
            return b.name === 'Medium' && b.present;
        });
    });
  
console.log(result);

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