deep-to-flat-object

Transforms a deep object into a flat object, assigning each value to a field named by its full path in the deep object.

• Array indexes are considered field names;
• It is possíble to determine a prefix to all field names through the options.pathPrefix;
• By default, if the field value is an object with a prototype, it is considered a final value and the recursion stops, preserving the prototype. It is possible to disable this behaviour by setting options.preservePrototype to false. In the example below, the ObjectId objects have their prototype preserved;

This project was developed to solve a problem where an object representing the MongoDB ObjectId would lose its prototype after the object being flattened, which caused some unexpected behaviors. It was solved by manually setting the prototype to the value of the MongoDB.ObjectId field. So, before you try this, I recommend checking this other very interesting project called flat. That may be better suited for most cases.

Example:

Input

    const objectId = mongoose.Types.ObjectId(); // ObjectId('626311d15dd8ead6df31db77')
    const objectId2 = mongoose.Types.ObjectId(); // ObjectId('626311d95dd8ead6df31db78')
    const date = new Date(); // 2022-04-22T20:37:54.496Z

    const deepObject = {
      a: {
        b: {
          f: [
            {
              g: objectId,
              i: 10,
            },
            {
              h: date,
            },
          ],
          j: [objectId2],
        },
        c: 1,
        d: '',
      },
    };

Output

    const flatObject = deepToFlatObject(deepObject);
    /**
    {
      'a.b.f.0.g': objectId, // ObjectId('626311d15dd8ead6df31db77')
      'a.b.f.0.i': 10,
      'a.b.f.1.h': date, // 2022-04-22T20:37:54.496Z
      'a.b.j.0': objectId2, // ObjectId('626311d95dd8ead6df31db78')
      'a.c': 1,
      'a.d': '',
    };
    */