Liquid Templating - Slate Documentation

What is Liquid Templating?

Liquid is a template language that lets you combine static text with dynamic data. In Slate workflows, you can use Liquid templating in:

Text blocks - Format and combine data from previous steps
LLM blocks - Build dynamic prompts with workflow data

Think of Liquid as a way to write templates with placeholders that get replaced with actual data when the workflow runs.

Where Can I Use Liquid?

Text Block

Use Liquid to format workflow data into readable text, reports, or structured output. Example:

# Keyword Report

Keyword: {{step_1.output.Keyword}}
Volume: {{step_1.output.Search_Volume}}

LLM Block

Use Liquid in prompts to include dynamic data from previous workflow steps. Example:

Write a blog post about {{step_1.output.topic}}.

Target these keywords: {{step_2.output | map: "Keyword" | join: ", "}}

The post should be {{step_3.output.word_count}} words long.

Basic Syntax

Output Tags

Use {{...}} to output data. Basic output:

{{step_1.output}}

Access object properties:

{{step_2.output.title}}
{{step_2.output.keyword}}
{{step_2.output.search_volume}}

Access array items:

{{step_3.output[0]}}
{{step_3.output[1].keyword}}

Logic Tags

Use {%...%} for control flow and logic. Examples:

{% if condition %}
  Show this
{% endif %}

{% for item in array %}
  {{item}}
{% endfor %}

Filters

Filters modify output values. Use the pipe | symbol to chain filters.

String Filters

Uppercase:

{{step_1.output | upcase}}

Input: "hello world" → Output: "HELLO WORLD" Lowercase:

{{step_1.output | downcase}}

Input: "HELLO WORLD" → Output: "hello world" Capitalize:

{{step_1.output | capitalize}}

Input: "hello world" → Output: "Hello world" Strip whitespace:

{{step_1.output | strip}}

Input: " hello " → Output: "hello" Replace:

{{step_1.output | replace: "old", "new"}}

Input: "old text" → Output: "new text" Remove:

{{step_1.output | remove: "word"}}

Input: "remove word here" → Output: "remove here" Truncate:

{{step_1.output | truncate: 20}}

Input: "This is a long sentence" → Output: "This is a long se..." Split into array:

{{step_1.output | split: ","}}

Input: "a,b,c" → Output: ["a", "b", "c"] Join array:

{{step_1.output | join: ", "}}

Input: ["a", "b", "c"] → Output: "a, b, c" Append:

{{step_1.output | append: " - suffix"}}

Input: "text" → Output: "text - suffix" Prepend:

{{step_1.output | prepend: "prefix - "}}

Input: "text" → Output: "prefix - text" Slice (substring):

{{step_1.output | slice: 0, 5}}

Input: "hello world" → Output: "hello" Strip HTML:

{{step_1.output | strip_html}}

Input: "<p>text</p>" → Output: "text" URL encode:

{{step_1.output | url_encode}}

Input: "hello world" → Output: "hello%20world" Escape:

{{step_1.output | escape}}

Input: "<html>" → Output: "<html>"

Number Filters

Plus:

{{step_1.output | plus: 10}}

Input: 5 → Output: 15 Minus:

{{step_1.output | minus: 3}}

Input: 10 → Output: 7 Times:

{{step_1.output | times: 2}}

Input: 5 → Output: 10 Divided by:

{{step_1.output | divided_by: 2}}

Input: 10 → Output: 5 Modulo:

{{step_1.output | modulo: 3}}

Input: 10 → Output: 1 Round:

{{step_1.output | round: 2}}

Input: 3.14159 → Output: 3.14 Ceil:

{{step_1.output | ceil}}

Input: 3.2 → Output: 4 Floor:

{{step_1.output | floor}}

Input: 3.9 → Output: 3

Array Filters

Size (length):

{{step_1.output | size}}

Input: ["a", "b", "c"] → Output: 3 First:

{{step_1.output | first}}

Input: ["a", "b", "c"] → Output: "a" Last:

{{step_1.output | last}}

Input: ["a", "b", "c"] → Output: "c" Join:

{{step_1.output | join: " | "}}

Input: ["a", "b", "c"] → Output: "a | b | c" Reverse:

{{step_1.output | reverse}}

Input: ["a", "b", "c"] → Output: ["c", "b", "a"] Sort:

{{step_1.output | sort}}

Input: ["c", "a", "b"] → Output: ["a", "b", "c"] Uniq (unique):

{{step_1.output | uniq}}

Input: ["a", "b", "a", "c"] → Output: ["a", "b", "c"] Map (extract property):

{{step_1.output | map: "keyword"}}

Input: [{"keyword": "crm"}, {"keyword": "sales"}] → Output: ["crm", "sales"] Where (filter by property):

{{step_1.output | where: "status", "active"}}

Input: [{"name": "a", "status": "active"}, {"name": "b", "status": "inactive"}] → Output: [{"name": "a", "status": "active"}]

Chaining Filters

You can chain multiple filters together:

{{step_1.output | downcase | replace: " ", "-" | truncate: 20}}

{{step_2.output | split: "," | sort | join: " | "}}

{{step_3.output | map: "keyword" | join: ", " | upcase}}

Control Flow

If Statements

Basic if:

{% if step_1.output == "approved" %}
Content is approved
{% endif %}

Input: step_1.output = "approved" Output:

Content is approved

Input: step_1.output = "rejected" Output: (empty)

If-else:

{% if step_1.output.volume > 10000 %}
High volume keyword
{% else %}
Low volume keyword
{% endif %}

Input: step_1.output.volume = 15000 Output:

High volume keyword

Input: step_1.output.volume = 5000 Output:

Low volume keyword

If-elsif-else:

{% if step_1.output.volume > 50000 %}
Very high volume
{% elsif step_1.output.volume > 10000 %}
High volume
{% else %}
Low volume
{% endif %}

Input: step_1.output.volume = 75000 Output:

Very high volume

Input: step_1.output.volume = 25000 Output:

High volume

Input: step_1.output.volume = 5000 Output:

Low volume

Multiple conditions with and:

{% if step_1.output.volume > 1000 and step_1.output.difficulty < 50 %}
Good opportunity
{% endif %}

Input: step_1.output.volume = 5000 and step_1.output.difficulty = 30 Output:

Good opportunity

Input: step_1.output.volume = 500 or step_1.output.difficulty = 60 Output: (empty)

Multiple conditions with or:

{% if step_1.output.status == "active" or step_1.output.status == "pending" %}
Show this content
{% endif %}

Input: step_1.output.status = "active" Output:

Show this content

Input: step_1.output.status = "pending" Output:

Show this content

Input: step_1.output.status = "inactive" Output: (empty)

For Loops

Basic loop:

{% for item in step_1.output %}
- {{item}}
{% endfor %}

Input: step_1.output = ["crm", "sales", "marketing"] Output:

- crm
- sales
- marketing

Loop with index:

{% for item in step_1.output %}
{{forloop.index}}. {{item}}
{% endfor %}

Input: step_1.output = ["crm", "sales", "marketing"] Output:

crm
sales
marketing

Access object properties in loop:

{% for keyword in step_1.output %}
Keyword: {{keyword.Keyword}}
Volume: {{keyword.Search_Volume}}
---
{% endfor %}

Input:

[
  {"Keyword": "crm", "Search_Volume": "165000"},
  {"Keyword": "sales", "Search_Volume": "74000"}
]

Output:

Keyword: crm
Volume: 165000
---
Keyword: sales
Volume: 74000
---

Loop with conditions:

{% for keyword in step_1.output %}
  {% if keyword.Search_Volume > 10000 %}
- {{keyword.Keyword}} ({{keyword.Search_Volume}} searches)
  {% endif %}
{% endfor %}

Input:

[
  {"Keyword": "crm", "Search_Volume": "165000"},
  {"Keyword": "email", "Search_Volume": "5400"},
  {"Keyword": "marketing", "Search_Volume": "74000"}
]

Output:

- crm (165000 searches)
- marketing (74000 searches)

Loop variables:

forloop.index - Current iteration (1-indexed)
forloop.index0 - Current iteration (0-indexed)
forloop.first - True if first iteration
forloop.last - True if last iteration
forloop.length - Total number of iterations

Example with loop variables:

{% for item in step_1.output %}
  {% if forloop.first %}
=== Top Results ===
  {% endif %}

{{forloop.index}}. {{item.title}}

  {% if forloop.last %}
=== End of Results ===
  {% endif %}
{% endfor %}

Input:

[
  {"title": "Article 1"},
  {"title": "Article 2"},
  {"title": "Article 3"}
]

Output:

=== Top Results ===

1. Article 1

2. Article 2

3. Article 3

=== End of Results ===

Limit iterations:

{% for item in step_1.output limit:5 %}
{{item}}
{% endfor %}

Input: step_1.output = ["item1", "item2", "item3", "item4", "item5", "item6", "item7", "item8"] Output:

item1
item2
item3
item4
item5

Skip items (offset):

{% for item in step_1.output offset:3 %}
{{item}}
{% endfor %}

Input: step_1.output = ["item1", "item2", "item3", "item4", "item5"] Output:

item4
item5

Unless (Negative If)

{% unless step_1.output.status == "error" %}
Processing successful
{% endunless %}

Input: step_1.output.status = "success" Output:

Processing successful

Input: step_1.output.status = "error" Output: (empty)

Case/When (Switch Statement)

{% case step_1.output.status %}
  {% when "approved" %}
    Approved
  {% when "pending" %}
    Pending Review
  {% when "rejected" %}
    Rejected
  {% else %}
    Unknown Status
{% endcase %}

Input: step_1.output.status = "approved" Output:

Approved

Input: step_1.output.status = "pending" Output:

Pending Review

Input: step_1.output.status = "rejected" Output:

Rejected

Input: step_1.output.status = "unknown" Output:

Unknown Status

Variables

Assign

Create variables to reuse values:

{% assign keyword_count = step_1.output | size %}
{% assign first_keyword = step_1.output | first %}

Total keywords: {{keyword_count}}
First keyword: {{first_keyword}}

Use case:

{% assign volume = step_1.output.Search_Volume | plus: 0 %}
{% if volume > 10000 %}
High volume: {{volume}}
{% endif %}

Capture

Capture multi-line content into a variable:

{% capture summary %}
Keywords analyzed: {{step_1.output | size}}
Top keyword: {{step_1.output[0].Keyword}}
Average volume: {{step_1.output | map: "Search_Volume" | avg}}
{% endcapture %}

{{summary}}

Comments

Single line comment:

{% comment %}This is a comment{% endcomment %}

Multi-line comment:

{% comment %}
This is a longer comment
that spans multiple lines
{% endcomment %}

Whitespace Control

Remove whitespace before:

{%- if condition -%}

Remove whitespace after:

{% for item in array -%}
{{item}}
{% endfor %}

Example:

{% for item in step_1.output -%}
{{item}},
{% endfor %}

Without -: "a, b, c, " With -: "a,b,c,"

Common Patterns

Extract Keywords from Array

{% assign keywords = step_1.output | map: "Keyword" | join: ", " %}

Target keywords: {{keywords}}

Format Numbers

{% assign volume = step_1.output.Search_Volume | plus: 0 %}
{% assign formatted_volume = volume | divided_by: 1000 %}

Search volume: {{formatted_volume}}K searches/month

Conditional Formatting

{% assign difficulty = step_1.output.Keyword_Difficulty_Index | plus: 0 %}

Difficulty: {{difficulty}}/100
{% if difficulty > 70 %}
Status: Very Difficult
{% elsif difficulty > 50 %}
Status: Moderate
{% else %}
Status: Easy
{% endif %}

Build Lists

{% for keyword in step_1.output %}
  {% if forloop.index <= 5 %}
{{forloop.index}}. {{keyword.Keyword}} ({{keyword.Search_Volume}} searches)
  {% endif %}
{% endfor %}

Combine Multiple Steps

# Analysis Report

## Keywords
{% for kw in step_1.output limit:3 %}
- {{kw.Keyword}}: {{kw.Search_Volume}} searches
{% endfor %}

## Domain
Domain: {{step_2.output.Domain}}
Traffic: {{step_2.output.Organic_Traffic}}

## Summary
{{step_3.output}}

Use Cases

Use Case 1: Dynamic LLM Prompts

In LLM block prompt:

Write a blog post about {{step_1.output.topic}}.

Target these keywords:
{% for kw in step_2.output limit:5 %}
- {{kw.Keyword}} ({{kw.Search_Volume}} searches)
{% endfor %}

The post should:
- Be {{step_3.output.word_count}} words long
- Target audience: {{step_3.output.audience}}
- Tone: {{step_3.output.tone}}

{% if step_1.output.include_examples %}
Include at least 3 real-world examples.
{% endif %}

Use Case 2: Format Data for Reports

In Text block:

# SEO Keyword Report

Generated: {{step_1.output.date}}

## Top Keywords

{% for keyword in step_2.output %}
### {{forloop.index}}. {{keyword.Keyword}}

- Search Volume: {{keyword.Search_Volume}}
- Difficulty: {{keyword.Keyword_Difficulty_Index}}/100
- CPC: ${{keyword.CPC}}
- Opportunity: {% if keyword.Keyword_Difficulty_Index < 50 %}High{% else %}Medium{% endif %}

{% endfor %}

Total keywords analyzed: {{step_2.output | size}}

Use Case 3: Build Structured Output

In Text block:

{% assign keywords = step_1.output | map: "Keyword" | join: ", " %}
{% assign total_volume = step_1.output | map: "Search_Volume" | sum %}
{% assign avg_difficulty = step_1.output | map: "Keyword_Difficulty_Index" | avg %}

Summary:
- Keywords: {{keywords}}
- Total Search Volume: {{total_volume}}
- Average Difficulty: {{avg_difficulty | round: 1}}

Best Practices

Template Design

Keep it readable: Use line breaks and indentation
Test incrementally: Build complex templates step by step
Comment complex logic: Use {% comment %} for clarity
Handle missing data: Use conditionals to check for data

Filter Usage

Chain wisely: Too many filters can be hard to debug
Convert types: Use | plus: 0 to convert strings to numbers
Extract early: Use map before join for cleaner code
Filter before loop: Process data before iteration when possible

Control Flow

Avoid deep nesting: Keep if/for logic simple
Use elsif: Better than multiple nested ifs
Check array length: Use {% if array.size > 0 %} before looping
Limit iterations: Use limit: for large arrays

Troubleshooting

Output is Blank

Problem: Template shows no output. Solution:

Check step references: {{step_X.output}}
Verify previous steps completed successfully
Test with simple output: {{step_1.output}}

Filter Not Working

Problem: Filter produces unexpected results. Solution:

Check filter syntax: {{value | filter: "param"}}
Ensure data type matches filter (string/number/array)
Chain filters one at a time to debug

Property Access Error

Problem: {{step_1.output.keyword}} shows blank. Solution:

Check exact property name (case-sensitive)
Verify object structure: {{step_1.output}}
Use array index if needed: {{step_1.output[0].keyword}}

Loop Not Working

Problem: For loop doesn’t produce output. Solution:

Verify input is an array
Check array isn’t empty: {{step_1.output | size}}
Ensure correct loop syntax: {% for item in step_1.output %}

Condition Not Working

Problem: If statement doesn’t behave as expected. Solution:

Check comparison operators: ==, >, <, >=, <=, !=
Convert strings to numbers: {% assign num = value | plus: 0 %}
Use and/or for multiple conditions

What’s Next

Now that you understand Liquid templating:

Format data with Text Block
Build dynamic prompts in LLM Block
Learn about Placeholder Referencing
Run workflows in bulk with Sheets

​What is Liquid Templating?

​Where Can I Use Liquid?

​Text Block

​LLM Block

​Basic Syntax

​Output Tags

​Logic Tags

​Filters

​String Filters

​Number Filters

​Array Filters

​Chaining Filters

​Control Flow

​If Statements

​For Loops

​Unless (Negative If)

​Case/When (Switch Statement)

​Variables

​Assign

​Capture

​Comments

​Whitespace Control

​Common Patterns

​Extract Keywords from Array

​Format Numbers

​Conditional Formatting

​Build Lists

​Combine Multiple Steps

​Use Cases

​Use Case 1: Dynamic LLM Prompts

​Use Case 2: Format Data for Reports

​Use Case 3: Build Structured Output

​Best Practices

​Template Design

​Filter Usage

​Control Flow

​Troubleshooting

​Output is Blank

​Filter Not Working

​Property Access Error

​Loop Not Working

​Condition Not Working

​What’s Next

What is Liquid Templating?

Where Can I Use Liquid?

Text Block

LLM Block

Basic Syntax

Output Tags

Logic Tags

Filters

String Filters

Number Filters

Array Filters

Chaining Filters

Control Flow

If Statements

For Loops

Unless (Negative If)

Case/When (Switch Statement)

Variables

Assign

Capture

Comments

Whitespace Control

Common Patterns

Extract Keywords from Array

Format Numbers

Conditional Formatting

Build Lists

Combine Multiple Steps

Use Cases

Use Case 1: Dynamic LLM Prompts

Use Case 2: Format Data for Reports

Use Case 3: Build Structured Output

Best Practices

Template Design

Filter Usage

Control Flow

Troubleshooting

Output is Blank

Filter Not Working

Property Access Error

Loop Not Working

Condition Not Working

What’s Next