Refining a JSON array using a preset list of values

Question

Refining a JSON array using a preset list of values

Just starting out with typescript in angular 2 and encountering a bit of a challenge. Here's the situation:

needle json 
[{"empId":100,"orgId":500}
{"empId":201,"orgId":566}]

The above json is structured in a specific order, and we need to preserve that order when searching for matching values in another json array (Haystack).

Haystack json array
[
{"empCode":21,"fname":"Ashish","Lname":"Shukla"},
{"empCode":22,"fname":"John","Lname":"Mark"},
{"empCode":21,"fname":"Vigil","Lname":"Rocker"},
{"empCode":201,"fname":"Rick","Lname":"Mandez"},
{"empCode":21,"fname":"Erik","Lname":"Francis"},
{"empCode":100,"fname":"Alex","Lname":"Mishra"},
{"empCode":21,"fname":"Feeder","Lname":"Kapoor"},
{"empCode":21,"fname":"Dan","Lname":"Rox"},
{"empCode":21,"fname":"Herb","Lname":"Deen"},
{"empCode":21,"fname":"Nate","Lname":"Diaz"},
{"empCode":21,"fname":"Nick","Lname":"Diaz"},
{"empCode":21,"fname":"Conor","Lname":"Pussy"}
]

My goal is to extract the values from the haystack array that match the ids in the needle array, while preserving the order specified in the needle.

{"empCode":100,"fname":"Alex","Lname":"Mishra"},
{"empCode":201,"fname":"Rick","Lname":"Mandez"}

I have a solution in place, but I suspect it may not be the most efficient as it involves multiple loops. Any suggestions for a more optimal approach?

NOTE: It's crucial to maintain the order of employee IDs in the result json as per the needle json.

Thank you very much :)

json typescript filtering

Answer 1

Answer №1

Here is the solution

let needle: any;
let hayStack: any;

needle = [
{"id": 1, "name": "Alice"},
{"id": 2, "name": "Bob"}
];

hayStack = [
{"id": 1, "firstName": "John", "lastName": "Doe"},
{"id": 2, "firstName": "Jane", "lastName": "Smith"},
{"id": 3, "firstName": "Tom", "lastName": "Jones"}
];

const needleIds = needle.map(item => item.id);
const haystackIds = hayStack.map(item => item.id);

const result = haystackIds.map((id, index) => {
if (needleIds.indexOf(id) != -1) {
  return hayStack[index];
}
}).sort().filter(item => (item != undefined));

console.log(result);

Final Result

0:{id: 1, firstName: "John", lastName: "Doe"}

1:{id: 2, firstName: "Jane", lastName: "Smith"}

Answer 2

Here is the solution

let needle: any;
let hayStack: any;

needle = [
{"id": 1, "name": "Alice"},
{"id": 2, "name": "Bob"}
];

hayStack = [
{"id": 1, "firstName": "John", "lastName": "Doe"},
{"id": 2, "firstName": "Jane", "lastName": "Smith"},
{"id": 3, "firstName": "Tom", "lastName": "Jones"}
];

const needleIds = needle.map(item => item.id);
const haystackIds = hayStack.map(item => item.id);

const result = haystackIds.map((id, index) => {
if (needleIds.indexOf(id) != -1) {
  return hayStack[index];
}
}).sort().filter(item => (item != undefined));

console.log(result);

Final Result

0:{id: 1, firstName: "John", lastName: "Doe"}

1:{id: 2, firstName: "Jane", lastName: "Smith"}

Refining a JSON array using a preset list of values

Answer №1

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