Variable Resolution in Postmate Client

Understand how Postmate resolves {{variableName}} at send time.

Resolution Order

When a request is sent, Postmate resolves variables in this priority order:

1. Runtime variables — set by pm.setVariable() during the current run (highest priority)
2. Active environment — key-value pairs in the currently selected environment
3. Unresolved — if no match is found, the literal {{variableName}} string is sent as-is

Variable Syntax

{{variableName}}

Variables are case-sensitive. {{authToken}} and {{AuthToken}} are different variables.

Use them anywhere in a request:

# URL
{{baseUrl}}/api/v1/users/{{userId}}

# Header value
Authorization: Bearer {{authToken}}

# Header name (rare but supported)
{{customHeaderName}}: {{customHeaderValue}}

# Body (JSON)
{ "tenantId": "{{tenantId}}", "name": "{{userName}}" }

# Body (Form)
email={{email}}&password={{password}}

Nested Variable References

Variables can reference other variables in their values:

# Environment variable: endpoint = /api/v1/users
# Environment variable: baseUrl  = https://api.myapp.com
# Result: https://api.myapp.com/api/v1/users
{{baseUrl}}{{endpoint}}

Debugging Unresolved Variables

If a variable isn't resolving as expected:

1. Check the active environment — confirm the variable name exists in the selected environment.
2. Check spelling and case — {{AuthToken}} ≠ {{authToken}}.
3. Check script execution order — if set in a pre-request script, ensure the script runs before the URL is resolved.
4. Use pm.log() — add pm.log(pm.getVariable('varName')) to your pre-request script to inspect the value.
5. Enable "Log as cURL" in settings — the logged cURL command shows the fully resolved request with all variable values substituted.