> For the complete documentation index, see [llms.txt](https://developer.harness.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.harness.io/continuous-delivery/troubleshooting-and-resources/knowledge-base-article/ternary-operator.md).

# 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 <a href="#example-use-a-ternary-operator-to-populate-a-tag-based-on-how-a-pipeline-started" id="example-use-a-ternary-operator-to-populate-a-tag-based-on-how-a-pipeline-started"></a>

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](/harness-ai/use-harness-platform/variables-and-expressions/harness-variables.md), 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 <a href="#example-get-a-default-value-from-the-trigger-payload" id="example-get-a-default-value-from-the-trigger-payload"></a>

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.

### Using isResolved and isUnresolved evaluation instead of null <a href="#using-isresolved-and-isunresolved-evaluation-instead-of-null" id="using-isresolved-and-isunresolved-evaluation-instead-of-null"></a>

Customers may be considering using a ternary evaluation that `== null` or `!= null` as the condition should consider using the `isResolved` and `isUnresolved` operators. In a null evaluation, this may not evaluate properly because the condition of a variable existing versus having a null value is slightly different.

For more information, please visit [the following Harness Article about utilizing the evaluations](/harness-ai/use-harness-platform/variables-and-expressions/harness-expressions-reference.md#check-expression-isresolved-isunresolved-null-replacement).