Nested filtering of array in Javascript

Question

I have two arrays:

countriesArr:

  [
      {
        "countryCode": "DEU",
        "name": "Germany",
        "companyFunctions": [
          {
            "name": "E-Commerce",
            "companyName": "Company 1"
          }
        ]
      },
      {
        "countryCode": "FRA",
        "name": "France",
        "companyFunctions": [
          {
            "name": "Shopping Centre",
            "companyName": "Company 1"
          },
          {
            "name": "Support Services",
            "companyName": "Company 2"
          },
          {
            "name": "Procurement Support",
            "companyName": "Company 3"
          },
          {
            "name": "Retail",
            "companyName": "Company 3"
          }
        ]
      }
    ]

and filterArr:

[
    {
        "name": "Company 2", 
        "id": "32434d324-32434"
    },
    {
        "name": "Company 3", 
        "id": "2643d3254-39244"
    }
]

What I want to do is filter the countriesArr by looping through the countriesArr array where countriesArr.companyFunctions.companyName === filterArr.name.

I wrote the following code:

countriesArr.filter(p =>
    p.companyFunctions.filter(cF =>
        filterArr.filter(c => c.name === cF.companyName)
    )
);

But this doesn't seem to work as it returns also the German object from countriesArr and it includes Company 1 in the companyFunctions of the French object from countriesArr while Company 1 isn't in the filterArr.

What am I doing wrong?

The desired result should look like:

[
  {
    "countryCode": "FRA",
    "name": "France",
    "companyFunctions": [
      {
        "name": "Support Services",
        "companyName": "Company 2"
      },
      {
        "name": "Procurement Support",
        "companyName": "Company 3"
      },
      {
        "name": "Retail",
        "companyName": "Company 3"
      }
    ]
  }
]

.filter() always returns an array. And every array (empty or not) is always truthy — Andreas
– Andreas, Commented Jul 20, 2020 at 14:28
@NinaScholz I have updated the question with the desired result. — O S
– O S, Commented Jul 20, 2020 at 14:31

Nina Scholz · Accepted Answer · 2020-07-20 15:25:10Z

2

You could rebuild a new object if companyFunctions contains the wanted names.

This approach take a hash table for wanted names where the property is true. This allows to filter later just with the destructured property companyName and a simple call of the property of names.

Finally, if the filteres array has a truthy (any other value except zero) length, take this array along with the rest of the object and pus a new object to the result set.

const
    countriesArr = [{ countryCode: "DEU", name: "Germany", companyFunctions: [{ name: "E-Commerce", companyName: "Company 1" }] }, { countryCode: "FRA", name: "France", companyFunctions: [{ name: "Shopping Centre", companyName: "Company 1" }, { name: "Support Services", companyName: "Company 2" }, { name: "Procurement Support", companyName: "Company 3" }, { name: "Retail", companyName: "Company 3" }] }],
    filterArr = [{ name: "Company 2", id: "32434d324-32434" }, { name: "Company 3", id: "2643d3254-39244" }],
    names = filterArr.reduce((r, { name }) => (r[name] = true, r), {}),
    result = countriesArr.reduce((r, { companyFunctions, ...o }) => {
        companyFunctions = companyFunctions.filter(({ companyName }) => names[companyName]);
        if (companyFunctions.length) r.push({ ...o, companyFunctions });
        return r;
    }, []);

console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

edited Jul 20, 2020 at 15:25

answered Jul 20, 2020 at 14:35

Nina Scholz

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1 Comment

O S Over a year ago

I would like to accept your answer could you briefly explain what is happening? It's very daunting to read.

Nikita Madeev · Accepted Answer · 2020-07-20 14:34:12Z

const countriesArr = [
    {
        countryCode: 'DEU',
        name: 'Germany',
        companyFunctions: [
            {
                name: 'E-Commerce',
                companyName: 'Company 1',
            },
        ],
    },
    {
        countryCode: 'FRA',
        name: 'France',
        companyFunctions: [
            {
                name: 'Shopping Centre',
                companyName: 'Company 1',
            },
            {
                name: 'Support Services',
                companyName: 'Company 2',
            },
            {
                name: 'Procurement Support',
                companyName: 'Company 3',
            },
            {
                name: 'Retail',
                companyName: 'Company 3',
            },
        ],
    },
];

const filterArr = [
    {
        name: 'Company 2',
        id: '32434d324-32434',
    },
    {
        name: 'Company 3',
        id: '2643d3254-39244',
    },
].map((f) => f.name);

const result = countriesArr
    .map((c) => ({
        ...c,
        companyFunctions: c.companyFunctions.filter((cf) => filterArr.includes(cf.companyName)),
    }))
    .filter((c) => c.companyFunctions.length > 0);

console.log(result);

bitifet · Accepted Answer · 2020-07-20 14:44:16Z

What you want is not a filter over countriesArr but a map() (to transform it) and then a filter() (to remove entries with 0 companyFunctions) or vice-versa (first filter() those having at least one matching companyFunction and then map to transform removing unwanted ones). But mapping and then filtering seems more straightforward to me...

const result = countriesArr                                                 
    .map(function(ca) {                                                     
        ca.companyFunctions = ca.companyFunctions.filter(                   
                cf => filterArr.some(fa=>fa.name==cf.companyName)           
        );                                                                  
        return ca;                                                          
    })                                                                      
    .filter(ca=>ca.companyFunctions.length)                                 
;                                                                           
                                                                            
console.log(JSON.stringify(result, null, 4));                               
// [                                                                        
//     {                                                                    
//         "countryCode": "FRA",                                            
//         "name": "France",                                                
//         "companyFunctions": [                                            
//             {                                                            
//                 "name": "Support Services",                              
//                 "companyName": "Company 2"                               
//             },                                                           
//             {                                                            
//                 "name": "Procurement Support",                           
//                 "companyName": "Company 3"                               
//             },                                                           
//             {                                                            
//                 "name": "Retail",                                        
//                 "companyName": "Company 3"                               
//             }                                                            
//         ]                                                                
//     }                                                                    
// ]

Sawan Patodia · Accepted Answer · 2020-07-20 14:42:20Z

var countriesArr = [{
    "countryCode": "DEU",
    "name": "Germany",
    "companyFunctions": [{
      "name": "E-Commerce",
      "companyName": "Company 1"
    }]
  },
  {
    "countryCode": "FRA",
    "name": "France",
    "companyFunctions": [{
        "name": "Shopping Centre",
        "companyName": "Company 1"
      },
      {
        "name": "Support Services",
        "companyName": "Company 2"
      },
      {
        "name": "Procurement Support",
        "companyName": "Company 3"
      },
      {
        "name": "Retail",
        "companyName": "Company 3"
      }
    ]
  }
];

var filterArr = [{
    "name": "Company 2",
    "id": "32434d324-32434"
  },
  {
    "name": "Company 3",
    "id": "2643d3254-39244"
  }
]

console.log(countriesArr.filter(item => {
  return filterArr.findIndex(company => item.companyFunctions.some(d => d.companyName === company.name)) != -1
}))

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