rows-diff

Compares two sets of rows, usually coming from a database, and returns the difference.

Usage

import rowsDiff from 'rows-diff';

var old_rows = [
  { id: 1, name: 'Jack Brower' },
  { id: 2, name: 'John Lock' },
];

var new_rows = [
  { id: 1, name: 'Jack Bower' },
  { id: 3, name: 'Scooby-Doo' },
];

var diff = rowsDiff(old_rows, new_rows, 'id');

/*
diff = {
  added: [ { id: 3, name: 'Scooby-Doo' } ],
  removed: [ 2 ],
  changed: [ { id: 1, name: 'Jack Bower' } ]
}
*/

let diff = rowsDiff(old_rows, new_rows, [options])

Compares two sets of rows, usually coming from a database, and returns the difference.

Every row must have a field that uniquely identifies the row. This is used to properly determine which rows were added, changed or deleted. By default this field is _id. You can specify a different keyfield with options.

Rows that exist in both sets (with equal keyfield) are compared using deep-equal. You can specify a different equalFunc with options. For instance, if every row contains a hash of its contents, equalFunc could look like this:

function equalHash(old_row, new_row) { return old_row.hash === new_row.hash }

parameters

old_rows: array of objects.

new_rows: array of objects.

options: Either an Object or a String (optional). See below for the possible fields. If options is a string, it represents the keyfield below.

options.keyfield: String. The field to use as a unique key (default: _id). Must be present in every row.

options.equalFunc: function(old_row, new_row). An optional function to compare two rows (default: deep-equal).

returns

If both sets of rows are equal, returns undefined

Otherwise it returns an object with the following fields:

added: array of rows that are in new_rows, but not in old_rows changed: array of rows from new_rows existed in old_rows but have changed deleted: array if the key's from the rows from old_rows that don't exist in new_rows

If any of those array's is empty, it is set to undefined.