Conditions¶

Condition instructions allows to execute different instructions depending on contextual informations such as the user age, an input form value, ...

These conditions are described using a very common expression syntax across programming languages, not so difficult to use but still very powerful.

Variables can be used in most parts of conditions.
Expression syntax is not restricted to conditions but can also be evaluated anywhere, simply by wrapping the expression with {% ... %}, as follows :

- emit:
    event: someEvent
    payload:
      is20GreaterThan18: "{% 20 > 18 %}" # Will evaluate to true
      currentTimestamp: "{% date({{run.date}}) %}" # Will evaluate to current timestamp

Basic operators¶

... greather than ... :
{{someAge}} > 18

... greather than or equals to ... :
{{someAge}} >= 18

... lower than ... :
{{someAge}} < 18

... lower than or equals to ... :
{{someAge}} <= 18

... equals ... :
{{someAge}} == 18
{{someAge}} = 18
{{cityName}} = "Toulouse"

... not equals ... :
{{someAge}} !== 18
{{someAge}} != 18

... matches ... :
"hello" matches "hel"

This also works with array of values, in which case it returns true if at least one element matches :
"hello" matches {{someArray}}

Is this variable defined ? :
{{testedVariable}}

Is this variable empty ? :
!{{testedVariable}}

... in ... :
{{someValue}} in {{someList}}
{{someKey}} in {{someObject}}
{{someKey}} not in {{someObject}} {{someKey}} not in "my,string,list" {{someKey}} not in {{myStringList}}

Testing variables types :
isArray(someVariable)
isObject(someVariable)

Logical operators¶

Multiple conditions can be chained with AND or OR :

... and ... :
{{someAge}} >= 18 and {{cityName}} == "Toulouse"
{{someAge}} >= 18 && {{cityName}} == "Toulouse"

... or ... :
{{someAge}} >= 18 or {{cityName}} == "Toulouse"
{{someAge}} >= 18 || {{cityName}} == "Toulouse"

Conditions can also be groupped and prioritized using parenthesis :
{{someCity}} == "Paris" || ({{someAge}} >= 18 && {{cityName}} == "Toulouse")

Conditions can be reverted :
{{someCity}} == "Paris" || ! ({{someAge}} >= 18 && {{cityName}} == "Toulouse") {{someCity}} == "Paris" || not ({{someAge}} >= 18 && {{cityName}} == "Toulouse")

Regular expressions¶

When using the match operator, a RegExp can also be provided with the regexp() keyword :
"luke.skywalker@gmail.com" matches regex(luke)

MongoDB-like conditional matches¶

Allows complex JSON object using MongoDB query syntax :

jsonmatch({{object}}, {{condition}})

Example of conditions :

{
  "$or": [
    {
      "test": "unknown",
    },
    {
      "one": {
        "$eq": "three",
      },
    },
  ]
}

This would match both objects {"test": "unknown"} and {"one": "three", "someOtherField": "..."}

See https://github.com/stalniy/ucast/tree/master/packages/mongo2js

Dates¶

Parsing¶

As long as they are ISO8601 dates, dates can be tested directly within conditions :

date("2022-04-13T08:00:05.493Z").hour == 8
date({{mydate}}).minute > 34 && date({{mydate}}).minute < 37
date({{mydate}}).second >= 5
date({{mydate}}).date == 23
date({{mydate}}).month >= 6 && date({{mydate}}).month < 10
date({{mydate}}).year == 2022
date({{mydate}}).day == 3
date({{mydate}}).day in {{allowedDays}}
date({{mydate}}).ts == 1649836805493
date({{mydate}}).iso == '2022-04-13T08:00:05.493Z'

Tested values are UTC based
day starts on 0 for Sunday (so 3 is Wednesday)

Formatting¶

Using this same date keyword, we can also generate localized & human readable date strings from some valid ISO8601 date :

date("2023-03-31T17:07:23.975Z", "l") == "3/31/2023"

date("2023-03-31T17:07:23.975Z", "DD/MM/YYYY") == "3/31/2023"

date("2023-03-31T17:07:23.975Z", "LT") == "7:07 PM"

date("2023-03-31T17:07:23.975Z", "LT", "fr") == "19:07"

date("2023-03-31T17:07:23.975Z", "lll", "fr") == "31 mars 2023 19:07"

date("2023-03-31T17:07:23.975Z", "l LT") == "3/31/2023 7:07 PM

date("2023-03-31T17:07:23.975Z", "LT", "fr", "America/New_York") == "13:07"

See all formatting options on https://day.js.org/docs/en/display/format.
Default language is English, but can be changed with the 3^rd parameter (see available languages).
Default time zone is 'Europe/Paris' (explaining the +2 hours shift above), but can be changed with the 4^th parameter.

Math¶

Operators¶

The following math operators are supported : +, -, *, /, % and parenthesis.

Examples:
1+1
1+{{someVariable}}
{{firstVar}} * {{secondVar}}
({{firstVar}} * {{secondVar}} + 10) / 2

Functions¶

rand lets you generate a random number greater than or equal to a minimum value and less than a maximum value :
rand(50, 150)
rand() without any parameter returns a random floating-point number between 0 and 1.

round lets you round a number to a specified precision (defaults to 0) :
round(10.2) == 10
round(10.2,1) == 10.2
round(10.26,1) == 10.3

ceil transform the decimal number to the smallest integer greater than or equal to a given number. ceil(10.1) == 11
ceil(10.9) == 11

Functions like rand() can also be combined with mathematical operators : rand(10, 11) * {{var}} + 2

String¶

JSON parsing or stringify¶

json('{"foo": "bar"}') == {"foo": "bar"}
json({"foo": "bar"}) == '{"foo": "bar"}'

String splitting / joining¶

split('one,two,thre', ',') == ['one', 'two', 'three']
join(['one', 'two', 'three'], ',') == 'one,two,thre'

String replacement¶

replace('hello world', 'world', 'there') == 'hello there'

Querystring¶

URLSearchParams("key1=value1&key2=value2").asJSON URLSearchParams({foo: "bar", abc: "xyz").asString == "foo=bar&abc=xyz"