ActualQL Functions

Joining Tables

You might have noticed the category.name field in the first few examples. What exactly is that field, and why can't we just use category?

The category field in transactions is an id. You can give it a specific category id to filter by that; you don't want to give it a name like Home because multiple categories can exist with the same name in different groups. By giving it a category id, you know you are getting back transactions specific to that category.

However, you often don't have a category id and want to just quickly search by category name. Using the . operator in a field name will "poke through" to the referenced table and allow you to access any fields on it. Here, we can access any fields on the categories table.

So filtering by category.name allows you to search by name instead of id. You could use any field for category; for example { 'category.is_income': true } would find all income categories.

Sorting

You can sort the results with the orderBy function:

q('transactions')
  .filter({ 'category.is_income': true })
  .select('*')
  .orderBy('category.name');

This returns transactions with an income category sorted by category name. You can also pass an array to orderBy to sort by multiple fields.

Aggregate Functions

You can specify aggregate functions in select for things like sums and counts. An example:

q('transactions')
  .filter({ 'category.name': 'Food' })
  .select({ total: { $sum: 'amount' } });

This sums up the amount of all transactions with the Food category (usually, you will filter by date too). Aggregate results must be named; here we named it total. You will get an error if you don't name it. (In the future, we may remove this restriction)

Since it's so common to select a single aggregate expression, ActualQL provides a different method for running them: calculate. The above query could be rewritten as:

q('transactions')
  .filter({ 'category.name': 'Food' })
  .calculate({ $sum: 'amount' });

Not only did we not have to name the result, data in the result will also be the summed value itself. If you use select, data will be an array with one element. The difference is that in the above you just use data, but if you used select you'd have to use data[0].total.