Flattening Nested Objects in TypeScript: Combining Multiple 'Entries' Properties into a Single Object

Flattening an array is one of useful transformation on the data, mainly for the data obtained through pagination api responses.

Say we have a data of this format and we want to flatten it.

[
  {
    entries: {
    '1': Object,
    '2': Object
    }
  },
  {
    entries: {
      '3': Object,
      '4': Object,
    }
  },
  {
    entries: {
      '5': Object,
      '6': Object,
    }
  }
]

I am using TypeScript to do this. You can code it in the language of your choice.

To flatten this array of objects into a single object with all the entries combined, you can use the reduce() method.

interface Entry {
  [key: string]: any; // replace `any` with the actual type of your objects
}

interface EntryWithEntries {
  entries: {
    [key: string]: Entry;
  };
}

const arrayOfObjects: EntryWithEntries[] = [
  {
    entries: {
      '1': { /* ... */ },
      '2': { /* ... */ }
    }
  },
  {
    entries: {
      '3': { /* ... */ },
      '4': { /* ... */ },
    }
  },
  {
    entries: {
      '5': { /* ... */ },
      '6': { /* ... */ },
    }
  }
];

const flattenedEntries: { [key: string]: Entry } = arrayOfObjects.reduce((accumulator, current) => {
  return { ...accumulator, ...current.entries };
}, {});

console.log(flattenedEntries);

In this example, we define two interfaces: Entry, which represents the type of the objects in the entries property, and EntryWithEntries, which represents the type of the objects in the arrayOfObjects array.

We then define a flattenedEntries variable and use the reduce() method to combine all the entries properties into a single object. The reduce() method takes a callback function that receives two parameters: accumulator, which is the accumulated result of the previous iterations, and current, which is the current element being processed.

Inside the callback function, we use the spread operator to merge the accumulator and current.entries objects into a new object, which is returned as the new accumulator. At the end of the reduce() method, we get an object that contains all the entries properties combined, with the keys being the string keys of the original entries properties.

I hope that helps!.... Will be back with another quick post.