Conditional Value Assignment

Learn how to assign different values to a variable based on row conditions or JEXL ternary expressions.

Scenario

In some cases, the value of a variable depends on the content of the incoming request. There are two approaches to conditional value assignment:

1. Row Condition: Execute the row only when a specific condition is met.
2. JEXL Ternary Expression: Decide which value to assign within a single row.

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Approach 1: Conditional Row Execution

Row conditions allow you to execute a row only when a specific condition is true. For the “false” case, set the default value as the fallback.

Example: Different Label Based on Status

Assign ACTIVE if the status field in the request body is active, otherwise assign PASSIVE.

Row 1 — Default value (always runs):

Field	Value
Build Mode	Template
Template	PASSIVE
Target	Custom Variable → statusLabel

Row 2 — Override when condition is met:

Field	Value
Row Condition	request.body.$.status == 'active'
Build Mode	Template
Template	ACTIVE
Target	Custom Variable → statusLabel

Result

Request Body	statusLabel Value
{"status": "active"}	ACTIVE
{"status": "passive"}	PASSIVE
{"status": "pending"}	PASSIVE

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Approach 2: JEXL Ternary Expression

A ternary expression makes the decision within a single row using the condition ? trueValue : falseValue syntax.

Example: Operation Type Based on HTTP Method

#{context.request.httpMethod == 'POST' ? 'create' : context.request.httpMethod == 'PUT' ? 'update' : context.request.httpMethod == 'DELETE' ? 'delete' : 'read'}

Result

HTTP Method	operationType Value
POST	create
PUT	update
DELETE	delete
GET	read

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Approach 3: Conditional JSON Part Generation

Generating an optional JSON object conditionally is one of the most powerful use cases. This is achieved by combining row conditions with custom variables.

Scenario

Include a metadata object in the body only if the type field in the request body is premium.

Row 1 — Default: empty JSON string:

Field	Value
Build Mode	Template
Template	null
Target	Custom Variable → metadataBlock

Row 2 — Override with row condition:

Field	Value
Row Condition	request.body.$.type == 'premium'
Build Mode	Template
Template	{"tier":"gold","features":["analytics","support"]}
Target	Custom Variable → metadataBlock

Row 3 — Final body template:

{"id":"#{body.$.id}","type":"#{body.$.type}","metadata":#{metadataBlock}}

Do not wrap #{metadataBlock} in quotes in the final template. Since the variable already contains valid JSON, adding quotes would turn it into a string, breaking the JSON structure.

Result

Request Body	metadata Value
{"id":1,"type":"premium"}	{"tier":"gold","features":["analytics","support"]}
{"id":2,"type":"basic"}	null

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When using row conditions with custom variables, define the default value in the first row (without a condition). This way, if no condition matches, the variable will still have a safe default value.