How to Format Jinja Templates

This guide describes the fundamental of Jinja templating and how to format it within your agents. Learn more about:

Benefits of Using Jinja Templates Variables Confirm Variable Existence Conditional Statements

Loops Filters Comments

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Overview

Jinja is a powerful templating language that allows you to create dynamic content by embedding logic and variables directly into your Block Agent. Instead of writing static, one-size-fits-all configurations, you can create intelligent, context-aware instructions that adapt based on run-time data.

 

Benefits of Using Jinja Templates

• Dynamic personalization:

  • Adapt agent personality based on brand guidelines.

  • Customize greetings based on customer history.

  • Tailor responses to patient status (new vs. returning).

• Conditional logic:

  • Show different content based on data availability.

  • Handle multiple scenarios within a single turn.

  • Create branching conversational flows.

• Data-Driven Instructions:

  • Access appointment data from external systems.

  • Display available time slots dynamically.

  • Reference customer information in prompts.

• Maintainability:

  • A single template supports multiple scenarios.

  • Centralized logic reduces duplication.

  • Policy-driven behavior changes without code updates.

• Reusability

  • Create reusable agent components.

  • Share templates across multiple implementations.

  • Standardize patterns across your AI platform.

 

Jinja Concepts

You can include Jinja templating in a variety of ways within your agent. It can be as simple as a variable for a company name, or as complex as filters that indicate a caller has an appointment coming up today so we should greet them differently.

 

Variables

Variables are enclosed in double curly braces and are replaced with their actual values at run-time.

Syntax

{{ variable_name }}

 

Sample Jinja Variable

Welcome to {{ arg_brand_name }}! Today's date is {{ arg_context_date_time }}.

The output from this variable might look like this:

Welcome to Dr. Teeth and Associates Dentistry! Today's date is 2025-12-11.

 

Confirm Variable Existence

Note: We recommend always checking if a variable exists before using it to avoid errors.

Syntax

{% if variable is defined %}
	{{ variable }}
{% endif %}

 

Sample Jinja Variable Existence Confirmation

{% if arg_existing_appointments is defined and arg_existing_appointments.matches is defined %}
	You have {{ arg_existing_appointments.matches|length }} upcoming appointments.
{% else %}
	I don't see any upcoming appointments in our system.
{% endif %}

 

Conditional Statements

Control what content appears based on conditions using if, elif (else if), and else.

Syntax

{% if condition %}
	content when true
{% else %}
	content when false
{% endif %}

 

Sample Jinja Conditional Statement

{% if arg_ani_match %}
	Welcome back! I see you've been here before.
{% else %}
	Welcome! Is this your first time calling?
{% endif %}

 

Loops

Iterate over collections of data like appointment lists or insurance providers.

Syntax

{% for item in collection %}
	Process {{ item }}
{% endfor %}

 

Sample Jinja Loop

Here are your upcoming appointments:
{% for appointment in arg_existing_appointments.matches %}
	- Appointment on {{ appointment.appointment_date }}
{% endfor %}

 

Filters

Transform data using pipe operators.

Commonly used filters include:

• |length: Get collection size

• |upper: Convert to uppercase

• |lower: Convert to lowercase

• |join(', '): Join list with delimiter

• |int: Convert to integer

• |format(): String format

 

Sample Jinja Filter

{% if arg_existing_appointments.matches|length > 0 %}
	You have {{ arg_existing_appointments.matches|length }} appointments.
{% endif %}

 

Comments

Induce non-rendered notes for documentation or your teammates.

Syntax

{# This is a comment and won't appear in output #}

 

 

Now that you've learn about how to format Jinja concepts, check out this page for how to integrate Jinja templating within a Block Agent.