Convert flat array of objects into nested array of objects

Question

Original JSON data (flat table):

[
    {\"id\":\"1\",\"first_name\":\"Jason\",\"last_name\":\"Martin\",\"start_date\":\"1996-07-25\",\"end_date\":\"2006-07-25\",         


        

Answer 1

You might take a look at the nest() operator from D3.js: https://github.com/mbostock/d3/blob/48ad44fdeef32b518c6271bb99a9aed376c1a1d6/src/arrays/nest.js This is part of D3, a larger library, but looking quickly at the code I just linked to, I don't think this has any dependencies, so you should be able to lift the code here for use in your own project. Usage is described here in the docs - you chain .key() methods to define the keys for each layer of the nested structure. In your case, this might look like:

data = d3.nest()
    .key(function(d) { return d.city })
    .key(function(d) { return d.description })
    .entries(data);

The structure this spits out is a little different from what you have, but it's functionally quite similar:

[
  {
    "key": "Toronto", 
    "values": [
      {
        "key": "Programmer", 
        "values": [
          {
            "active": "1", 
            "city": "Toronto", 
            "department": "Finance", 
            "description": "Programmer", 
            "end_date": "2006-07-25", 
            "first_name": "Jason", 
            "id": "1", 
            "last_name": "Martin", 
            "salary": "1234.56", 
            "start_date": "1996-07-25"
          },
          // etc ...
        ]
      }
    ]
  },
  // etc ...
]