Query Expression Syntax

Airscript includes a Query Expression syntax that allows you to operate on lists of items. This syntax looks somewhat similar to SQL but is based on a concept called Language Integrated Query.

Using this syntax you can filter or map a list of items.

The general syntax looks like the following:

FROM
  item
IN
  collection
WHERE
  item.score > 80
SELECT
  item

In this simple example we go through a collection and filter out all items that have a score property greater than 80.

The following example shows one way to nest a Query Expression within a Query Expression.

FROM
  qualifiedPerson
IN
  FROM
    person
  IN
    collectionOfPoeple
  WHERE
    person.qualified = true
  SELECT
    person
WHERE
  qualifiedPerson.score > 80
SELECT
  qualifiedPerson

In this example we are pulling only qualified people out of a collection of people and then looking for people in that collection that have a score greater than 80.

Any valid Airscript function is valid within our syntax. For example, below we use the Airscript STRING_FIND in the WHERE clause.

FROM
  p
IN
  persons
WHERE
  STRING_FIND(p.name, "Bob") >= 0
SELECT
  p.name

This example is going through all persons and finding all persons who have a name that contains Bob in it. Then we are returning the name of those persons. This will return as a list of p.name

While this is the basic example of our syntax here, we have even more functionality baked into our syntax. The supported technical arguments are:

FROM
    itemBinding = identifier,
  [ indexBinding = identifier, [ collectionBinding = identifier ] ]
IN
    expression
[WHERE expression]
[ORDER_BY expression direction = (ASC | DESC)]
[LIMIT expression [OFFSET expression]]
SELECT [DISTINCT] selectExpression

Anything in brackets ([]) means that it is optional. We do not need to have a WHERE clause. There are also ORDER_BY clause and LIMIT options. If you want your result to return only unique items you can put the DISTINCT modifier on your select and you receive a SET with duplicate items removed.

One other important note: there is an index binding, meaning that you can can also get the index of the item you are at in your iteration. For example:

FROM
  item, index
IN
  [{"foo": "bar"}, {"foo": "baz"}]
SELECT
  {"": item}

In this case index is a special reserved word that you put the end of your expression and you can then refer to it in the rest of your statement. The result will be:

[
  {
    "0": {
      "foo": "bar"
    }
  },
  {
    "1": {
      "foo": "baz"
    }
  }
]

We hope you find this syntax helpful in your application builds!