How to get data from nested arrays in array object

Question

I have an object array like this

array = {
    "microservices": [
        {
            "id": 1,
            "permissions": [
                {
                    "id": 65,
                    "name": "Default permission"
                },
                {
                    "id": 64,
                    "name": "Super user Access"
                }
            ]
        },
        {
            "id": 2,
            "permissions": []
        },
        {
            "id": 3,
            "permissions": [
                {
                    "id": 18,
                    "name": "Script: Update"
                },
                {
                    "id": 15,
                    "name": "Application: Delete"
                },
                {
                    "id": 9,
                    "name": "Workspace: Create"
                }
            ]
        }
    ]
}

from microservices array I only want to get "permissions" arrays and stores to a new variable, I searched for it but not get any relevant solution, thanks in advance

Naren Murali · Accepted Answer · 2019-02-07 09:57:29Z

2

You could use the map operator and fetch that specific property alone. Please check the below JS example.

const array = {
  "microservices": [{
      "id": 1,
      "permissions": [{
          "id": 65,
          "name": "Default permission"
        },
        {
          "id": 64,
          "name": "Super user Access"
        }
      ]
    },
    {
      "id": 2,
      "permissions": []
    },
    {
      "id": 3,
      "permissions": [{
          "id": 18,
          "name": "Script: Update"
        },
        {
          "id": 15,
          "name": "Application: Delete"
        },
        {
          "id": 9,
          "name": "Workspace: Create"
        }
      ]
    }
  ]
}
const output = []
array.microservices.map(function(x) {
  output.push(...x.permissions);
})
console.log(output);

edited Feb 7, 2019 at 9:57

answered Feb 7, 2019 at 9:33

Naren Murali

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2 Comments

Raza Ellahi Over a year ago

your solution works, but i need data in only one array, like this [ { "id": 65, "name": "Default permission" }, { "id": 64, "name": "Super user Access" } , { "id": 18, "name": "Script: Update" }, { "id": 15, "name": "Application: Delete" }, { "id": 9, "name": "Workspace: Create" } ]

Naren Murali Over a year ago

@RazaEllahi Can you check my updated answer, whether its correct?

Amith Dissanayaka · Accepted Answer · 2019-02-07 09:41:31Z

2

Simply you have to iterate the json object as follows. New array "Permissions" will return your data.

 getPermissions(){
   this.array.microservices.forEach(element => {
    element.permissions.forEach(ele => {
      this.permissions.push(ele);
     });
   });

   console.log(this.permissions);       
 }

In advance You can use .map operator also..

answered Feb 7, 2019 at 9:41

Amith Dissanayaka

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Comments

Nguyen Phong Thien · Accepted Answer · 2019-02-07 09:34:39Z

0

This is not a specific Angular or Typescript question, but you can do it like this

const whatYouNeed = array.microservices.reduce((sum, item) => {
    sum.push(item.permissions);
    return sum;
}, []);

or if you want it to be a single level:

const whatYouNeed = array.microservices.reduce((sum, item) => {
    sum = sum.concat(item.permissions);
    return sum;
}, []);

answered Feb 7, 2019 at 9:34

Nguyen Phong Thien

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1 Comment

Raza Ellahi Over a year ago

your solution works, but i need data in only one array, like this [ { "id": 65, "name": "Default permission" }, { "id": 64, "name": "Super user Access" } , { "id": 18, "name": "Script: Update" }, { "id": 15, "name": "Application: Delete" }, { "id": 9, "name": "Workspace: Create" } ]

Dhananjai Pai · Accepted Answer · 2019-02-07 09:35:09Z

0

Since you want a single array of all permissions, this would be the cleanest approach. Read about flatMap here

 const permissions = array.microservices.flatMap(i => i.permissions)     
 console.log(permissions);

Use a polyfill for browser support. Available in the above link.

answered Feb 7, 2019 at 9:35

Dhananjai Pai

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Comments

korteee · Accepted Answer · 2019-02-07 09:35:35Z

0

You can use ES6 map.

const permissionsArrays = array.microservices.map(microservice => microservice.permissions)

answered Feb 7, 2019 at 9:35

korteee

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Comments

Michael Mano · Accepted Answer · 2019-02-07 09:37:23Z

First you have an object which contains an array not an actual array. But let's ignore that for now.

array =  {
  "microservices": [
    {
      "id": 1,
      "permissions": [
        {
          "id": 65,
          "name": "Default permission"
        },
        {
          "id": 64,
          "name": "Super user Access"
        }
      ]
    },
    {
      "id": 2,
      "permissions": []
    },
      {
      "id": 3,
      "permissions": [
        {
          "id": 18,
          "name": "Script: Update"
        },
        {
          "id": 15,
          "name": "Application: Delete"
        },
        {
          "id": 9,
          "name": "Workspace: Create"
        }
      ]
    }
   ]
 }


const permissions = array.microservices.map(item => {
    return item.permissions;
});

Robert · Accepted Answer · 2019-02-07 09:44:05Z

So assuming that, this is the json data that your recevice:

{
  "microservices": [
    {
      "id": 1,
      "permissions": [
        {
          "id": 65,
          "name": "Default permission"
        },
        {
          "id": 64,
          "name": "Super user Access"
        }
      ]
    },
    {
      "id": 2,
      "permissions": []
    },
      {
      "id": 3,
      "permissions": [
        {
          "id": 18,
          "name": "Script: Update"
        },
        {
          "id": 15,
          "name": "Application: Delete"
        },
        {
          "id": 9,
          "name": "Workspace: Create"
        }
      ]
    }
   ]
 }

Just create an interface, to use intellisense:

export interface Microservice {
  microservices?: (MicroservicesEntity)[] | null;
}
export interface MicroservicesEntity {
  id: number;
  permissions?: (PermissionsEntity | null)[] | null;
}
export interface PermissionsEntity {
  id: number;
  name: string;
}

In that way you can gain the help of intellisense, so access the data by reference the interface to the json data:

data: Microservice;

After that use map to gain the array of permission

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