Condition Syntax

Learn about Workflow Trigger Condition Syntax.

Telemetry trigger conditions are written like logical statements that are to be evaluated, but without the common “if/then” syntax. The conditions can be complex, including and/or logic, and nested parenthesis.

There is a lot of information below because you can do some quite sophisticated things in triggers. To help you find your way, here’s a handy index (with links):

Class	Subclass	A Few Examples
Operands	Literal	Booleans, integers, floats
	Telemetry	event.code, metric.value, status.name
	Devices	device.id, device.tags["tag_name"]
Operators	Arithmetic	+ - * /
	Comparison	== != < > <= >=
	Logical	and, or, not
	String	contains, startswith, endswith

To help guide you, there are some condition examples here.

The syntax can be quite complicated and, in fact, there are very additional built-in commands not described in this page. maiLink leverages a 3rd party libary for expression resolution in condition syntax evaluation. The details shown above represent the core features of the condition syntax. There are, however, further ways to construct conditions. maiData has neither used nor tested the additional methods that you can find described at antonmedv’s GitHub page at Expr Library Documentation.

Operands

Conditions are logical statements comprised of operands and operators. The operands allow you to test telemetry messages that are received. They also allow testing of other information about the device.

Literal Operands

Type	Description	Example
Boolean	One of: true, false	false
Integer	An integer value.	55.3
Float	A floating point value.	55.3
String	ASCII characters enclosed in single or double quotes (' ' or " “).	“motor_rpm”
Array	A list of literal operand values enclosed in square brackets.	[1, 2, 3]
Range	An inclusive range of integers	4..45

Operands From Telemetry Messages

Operand	Type	Description
event.code	string	The code of the event.
event.text	string	A text blurb that describes the the event.
event.severity	number	The severity level of the event.
metric.label	string	The identifier of the metric.
metric.value	number	The value of the metric.
status.name	string	The identifier of the status.
status.value	string	The value of the status.

Operands From Device Information

Operand	Type	Description
device.id	string	The id of the device. This may be useful with the “contains”, “startswith” or “endswith” string operators.
device.name	string	The name of the device. This may be useful with the “contains”, “startswith” or “endswith” string operators.
device.status["status_name"]	string	The most recently received status value of status telemetry “status_name”.
device.tags["tag_name"]	string	The current value of device tag “tag_name”.
device.type	string	The device model (also known as device type) is defined for the workflow, so is probably not needed as an operand.

Operators

Arithmetic Operators

maiLink workflows support common arithmetic operators in condition statements:

Operator	Description	Example
+	Addition	metric.value * 3
-	Subtraction	metric.value - 3
*	Multiplication	metric.value * 3
/	Division	metric.value / 3
%	Modulus	metric.value % 3
^ or **	Exponent	metric.value ^ 3

Comparison Operators

maiLink workflows support common comparison operators in condition statements:

Operator	Description	Example
==	Tests if the values of two operands are equal or not; if yes, the condition becomes true.	event.code == “E1003”
!=	Tests if the values of two operands are equal or not; if the values are not equal, then the condition becomes true.	status.label != “sw_version”
<	Tests if the value of left operand is less than the value of the right operand; if yes, the condition becomes true. Intended for metric messages because it is a numeric test.	metric.value < 55
>	Tests if the value of left operand is greater than the value of right operand; if yes, the condition becomes true. Intended for metric messages because it is a numeric test.	metric.value > 55
<=	Tests if the value of left operand is less than or equal to the value of right operand; if yes, the condition becomes true. Intended for metric messages because it is a numeric test.	metric.value <= 55
>=	Tests if the value of the left operand is greater than or equal to the value of the right operand; if yes, the condition becomes true. Intended for metric messages because it is a numeric test.	metric.value >= 55
in	Tests if the first operand is an integer within the range of values specified by second operand.	metric.value in 33..166

Logical Operators

maiLink workflows support common comparison operators in condition statements:

Operator	Description	Example
not or !	Logical NOT operator.	not (event.code == “E1003”)
and or &&	Logical AND operator.	(event.code == “E1003”) and (event.severity > 50)
or or \|\|	Logical OR operator.	(event.code == “E1003”) and (event.severity > 50)
not	Logical NOT operator.	not (event.code == “E1003”)

String Operators

maiLink workflows support the common string operators in condition statements:

Operator	Description	Example
contains	Tests if first operand contains the second operand in its entirety, with identical case.	event.code contains “E10”
endswith	Tests if end of the second operand is the exact ending of the second operand, with identical case.	metric.label endswith “_rpm”
in	Tests if the first operand equals an element in an array of strings, with identical case.	status.name in [“SWversion”,“SWoriginal”]
matches	Tests if the value of first operand is matches the regular expression given as the second operand	event.code matches “^._rpm_.”
startswith	Tests if end of the second operand is the exact beginning of the first operand , with identical case.	metric.label startswith “airlock_”

Condition Syntax Examples

These examples show some more complicated types of condition syntaxes.

Type	Example Condition
Event	event.code == “E1003”
Event	event.code == “E0113” and device.tags[“contract”] in [“Warranty”,“Expired”]
Event	event.code == “E1003” or event.code == ”E1388”
Event	event.code in [“E1003”,”E1388”]
Event	event.code matches “^E1[0-9][0-9][0-9]$”
Metric	metric.label == “motor_rpm” and metric.value < 55
Metric	metric.label == “motor_rpm” and metric.value < 55 and metric.value > 33
Metric	metric.label == “motor_rpm” and metric.value < 55 and device.tags[“motor size”] == ”small”
Status	status.name == “version” and status.value == “1.3.2”
Status	Status.name == ”version” and status.value != device.tags[“RequiredVersion”]