How to push similar object elements in single array using node js?

Question

I am retrieving some data from PostgreSQL using node js API call. In this I am using 2 different pg tables. I am checking condition if "unit_code" is equal to "fk_unit_code" then it should combine the respective values from "Group_individuals" column and push it to the array. To get the "userData" I am doing left join between 2 tables. I have tried below code but its pushing single row per iteration of for loop.

function buildObject(userData){

for (var i = 0; i < userData.length; i++){
myArray = new Array() // at each iteration this will be empty and we get new group of "Group_individuals"
if(userData[i].unit_code=== userData[i].fk_unit_code){

                        myArray.push(userData[i].Group_individuals)
                        console.log(myArray)

            }
     }
}

Data available in "userData" is as below:

[
    { Group_individuals  : 'John',
      unit_code   : 2,
      fk_unit_code: 2,
    }
    { Group_individuals  : 'Rocky',
      unit_code   : 2,
      fk_unit_code: 2,
    }
    { Group_individuals  : 'Alex',
      unit_code   : 3,
      fk_unit_code: 3,
    }
    { Group_individuals  : 'Prince',
      unit_code   : 3,
      fk_unit_code: 3,
    }
    { Group_individuals  : 'James',
      unit_code   : 2,
      fk_unit_code: 2,
    }

]

I want that myArray should look like: In first iteration myArray = [John, Rocky, James] In second iteration myArray = [Alex, Prince]

vcode · Accepted Answer · 2020-01-23 16:19:22Z

1

    var userData = [{
    	Group_individuals: 'John',
    	unit_code: 2,
    	fk_unit_code: 2,
    },{
    	Group_individuals: 'Rocky',
    	unit_code: 2,
    	fk_unit_code: 2,
    },{
    	Group_individuals: 'Alex',
    	unit_code: 3,
    	fk_unit_code: 3,
    },{
    	Group_individuals: 'Prince',
    	unit_code: 3,
    	fk_unit_code: 3,
    },{
    	Group_individuals: 'James',
    	unit_code: 2,
    	fk_unit_code: 2,
    }]
    var result = {};
    
    for (var i in userData) {
    	if (userData[i].unit_code != userData[i].fk_unit_code)
    		continue;
    	var key = `${userData[i].unit_code}${userData[i].fk_unit_code}`;
    
    	result[key] = result[key] || [];
    
    	result[key].push(userData[i].Group_individuals);
    
    }
    
    console.log(result);

edited Jan 23, 2020 at 16:19

answered Jan 23, 2020 at 15:48

vcode

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2 Comments

Andrew L Over a year ago

might be nice to explain this answer to OP so they can learn a bit (as well as future readers too)

Kaustubh Ghole Over a year ago

@vcode Your answer is really appreciated, This helped me to achieve what I was expecting. Thank you !!!

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