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Use ternary operators with triggers

The ternary operator, also known as the conditional operator, is a shorthand notation for expressing conditional statements in various programming languages. It takes three operands and allows you to evaluate a condition and choose one of two expressions to execute based on the result of the condition.

The syntax of the ternary operator is generally as follows:

condition?expression1:expression2

Here's how it works:

  1. The "condition" is an expression that evaluates to either true or false.
  2. If the condition is true, the expression before the colon (" : ") is executed and becomes the value of the entire expression.
  3. If the condition is false, the expression after the colon is executed and becomes the value of the entire expression.

Example: Use a ternary operator to populate a tag based on how a pipeline started​

For this example, assume you need to create a trigger for a CD pipeline that automatically takes the tag value from <+trigger.payload.tag> if pipeline is executed from a webhook trigger, or else it takes the tag from from <+pipeline.variables.tag> if the pipeline is executed manually.

Because you can ternary operators with Harness expressions, you can create a condition like:

<+condition?IF_TRUE:IF_FALSE>

For the true condition, <+pipeline.triggerType> should be WEHOOK_CUSTOM, and for the false condition you can use a runtime input (<+input>) or a pipeline variable.

The resulting ternary operator condition could be something like:

<+<+pipeline.triggerType>=="MANUAL"?<+pipeline.variables.tag>:<+trigger.payload.tag>>

Example: Get a default value from the trigger payload​

Suppose you have a trigger that provides runtime input for a pipeline from the trigger payload.

You could configure the trigger as follows, if the value is always available from the payload:

myVariable: <+trigger.payload.myVariable>

However, if you want to provide a default value for myVariable when the value is missing from the trigger payload, you can use a ternary operator with Harness expressions, such as:

<+<+trigger.payload>.contains("myVariable")?<+trigger.payload.myVariable>:"DEFAULT_VALUE">

This ensures that myVariable takes a default value of "DEFAULT_VALUE" if the variable is not present in the payload.