Template System Overview
Learn about moclojer's powerful template system that allows you to create dynamic responses based on request data, making your mocks more realistic and flexible.
moclojer's template system is what makes your mock APIs dynamic and realistic. Instead of returning the same static response every time, templates let you create responses that change based on the incoming request data.
What are templates?
Templates are special placeholders in your response configuration that get replaced with actual values when a request is processed. They use a simple {{variable}} syntax that's easy to read and write.
Example:
- endpoint:
method: GET
path: /users/:id
response:
body: >
{
"id": "{{path-params.id}}",
"name": "User {{path-params.id}}",
"timestamp": "{{now}}"
}When someone requests /users/123, the response becomes:
{
"id": "123",
"name": "User 123",
"timestamp": "2024-01-15T10:30:00Z"
}Why use templates?
🎯 Realistic Testing
Simulate how real APIs behave by returning different data based on the request:
- endpoint:
method: GET
path: /products/:category
response:
body: >
{
"category": "{{path-params.category}}",
"products": [
{"id": 1, "name": "{{path-params.category}} Product 1"},
{"id": 2, "name": "{{path-params.category}} Product 2"}
]
}🔄 Dynamic Responses
Create responses that reflect the input data:
- endpoint:
method: POST
path: /orders
response:
body: >
{
"order_id": "ORD-{{json-params.user_id}}-{{now}}",
"user_id": {{json-params.user_id}},
"total": {{json-params.total}},
"status": "confirmed"
}🧪 Flexible Testing
Test different scenarios without creating multiple endpoint configurations:
- endpoint:
method: GET
path: /api/status
response:
body: >
{
"environment": "{{query-params.env}}",
"debug": {{query-params.debug}},
"timestamp": "{{now}}"
}Template Variables
moclojer provides several types of template variables:
Path Parameters
Extract values from URL paths:
path: /users/:id/posts/:postId
body: >
{
"user_id": "{{path-params.id}}",
"post_id": "{{path-params.postId}}"
}Query Parameters
Use URL query string values:
# For request: /search?q=javascript&limit=10
body: >
{
"query": "{{query-params.q}}",
"limit": {{query-params.limit}},
"results": []
}JSON Body Parameters
Access data from JSON request bodies:
# For POST with body: {"name": "John", "email": "[email protected]"}
body: >
{
"id": 123,
"name": "{{json-params.name}}",
"email": "{{json-params.email}}",
"created_at": "{{now}}"
}Request Headers
Use values from HTTP headers:
body: >
{
"user_agent": "{{header-params.User-Agent}}",
"authorization": "{{header-params.Authorization}}",
"content_type": "{{header-params.Content-Type}}"
}Built-in Functions
Special functions for common needs:
body: >
{
"timestamp": "{{now}}",
"random_id": "{{uuid}}",
"server_time": "{{now}}"
}Common Patterns
Echo Responses
Return the same data that was sent:
- endpoint:
method: POST
path: /echo
response:
body: >
{
"received": {
"name": "{{json-params.name}}",
"email": "{{json-params.email}}"
},
"processed_at": "{{now}}"
}Personalized Responses
Create user-specific responses:
- endpoint:
method: GET
path: /profile/:username
response:
body: >
{
"username": "{{path-params.username}}",
"welcome_message": "Hello, {{path-params.username}}!",
"last_login": "{{now}}"
}Search Results
Dynamic search responses:
- endpoint:
method: GET
path: /search
response:
body: >
{
"query": "{{query-params.q}}",
"page": {{query-params.page}},
"results": [
{"title": "Result 1 for {{query-params.q}}"},
{"title": "Result 2 for {{query-params.q}}"}
]
}API Keys and Authentication
Handle authentication scenarios:
- endpoint:
method: GET
path: /protected
response:
body: >
{
"user": "authenticated",
"api_key": "{{query-params.api_key}}",
"access_level": "full"
}Template Best Practices
1. Use Meaningful Names
# Good
path: /users/:userId/orders/:orderId
# Less clear
path: /users/:id1/orders/:id22. Handle Missing Values
Provide defaults for optional parameters:
body: >
{
"page": {{query-params.page}},
"limit": {{query-params.limit}},
"default_message": "Page {{query-params.page}} with {{query-params.limit}} items"
}3. Keep Templates Readable
Break complex templates into logical sections:
body: >
{
"user": {
"id": "{{path-params.id}}",
"name": "{{json-params.name}}"
},
"metadata": {
"created_at": "{{now}}",
"source": "{{header-params.User-Agent}}"
}
}4. Use Consistent Formatting
Follow JSON formatting rules:
# Strings need quotes
"name": "{{json-params.name}}"
# Numbers don't need quotes
"count": {{query-params.count}}
# Booleans don't need quotes
"active": {{json-params.active}}Advanced Template Features
Nested Object Access
Access nested properties from JSON:
# For body: {"user": {"profile": {"name": "John"}}}
body: >
{
"welcome": "Hello, {{json-params.user.profile.name}}!"
}Conditional Content
Simple conditional logic:
body: >
{
"message": "{{#if query-params.admin}}Admin access granted{{else}}Regular user{{/if}}"
}Array Handling
Work with array data:
# For body: {"tags": ["javascript", "tutorial"]}
body: >
{
"first_tag": "{{json-params.tags.0}}",
"tag_count": {{json-params.tags.length}}
}Error Handling
Templates gracefully handle missing data:
- endpoint:
method: GET
path: /user-info
response:
body: >
{
"user_id": "{{query-params.id}}",
"note": "If id parameter is missing, it shows as empty string"
}What's Next?
Now that you understand the template system basics, dive deeper into specific areas:
Template Variables - Complete reference of all available variables
Dynamic Content - Advanced techniques for dynamic responses
Advanced Templating - Complex templating patterns and best practices
Examples in Action
See templates in real-world scenarios:
REST API Example - Complete API with templates
E-commerce API - Product catalog with dynamic data
User Management - User CRUD operations
Need Help?
Template Variables Reference - All available template variables
FAQ - Common template questions
GitHub Discussions - Community help
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