Shopify Liquid MCP Server

# Liquid Basics - Complete Guide ## Overview Liquid is a template language that enables developers to interact with data through tags, filters, and objects. This guide covers fundamental concepts necessary for effective Liquid implementation. ## Object Handles Objects representing store resources (products, collections, articles, blogs) use handles for identification and URL construction. ### Handle Generation Rules Handles follow standardized formatting: - Always lowercase - Whitespace and special characters convert to hyphens - Multiple consecutive special characters become a single hyphen - Leading whitespace or special characters are removed - Duplicate titles auto-increment (e.g., `potion` and `potion-1`) **Important:** Changing a resource title after creation does not update its handle. Individual links within `linklists` have handles based on titles but cannot be modified directly. ### Referencing Handles Objects with handles expose a `handle` property. Access methods include: **Square Bracket Notation:** `pages['about-us'].url` - Accepts quoted handles, variables, or object references **Dot Notation:** `settings.predictive_search_enabled` - Accepts unquoted handles ## Logical and Comparison Operators | Operator | Function | |----------|----------| | `==` | Equals | | `!=` | Does not equal | | `>` | Greater than | | `<` | Less than | | `>=` | Greater than or equal to | | `<=` | Less than or equal to | | `or` | Condition A or Condition B | | `and` | Condition A and Condition B | | `contains` | String/array presence check | ### The `contains` Operator The `contains` operator checks for string presence within strings or arrays. It cannot validate object existence in object arrays. ### Order of Operations Operators evaluate right-to-left without changeable precedence. "Parentheses are invalid characters within Liquid tags and will prevent rendering." ## Data Types Liquid supports six data types: ### String Any character series wrapped in single or double quotes. Use the `blank` object to check for empty strings. ### Number Numeric values including floats and integers. ### Boolean Binary values: `true` or `false`. ### Nil Undefined values that print nothing and evaluate as `false`. A string containing "nil" differs from the `nil` type. ### Array Variable lists accessible through loops or index notation starting at zero. Arrays cannot be initialized in Liquid alone but can be created using the split filter. ### Empty An `empty` object returns when accessing undefined objects (deleted pages, products, or valueless settings). Compare objects with `empty` before accessing attributes. ## Truthy and Falsy Values Understanding truthiness is critical for conditional logic: **Falsy Values:** - `false` - `nil` **Truthy Values:** - `true` - Empty strings - `0` (zero) - Integers and floats - Arrays (including empty arrays) - Pages and objects **Key Consideration:** Empty strings are truthy—use `blank` for validation. `EmptyDrop` objects are also truthy—compare with `empty` for proper checking. ## Whitespace Control Liquid tags generate output lines regardless of text content. Include hyphens in tag syntax to strip surrounding whitespace. **Syntax Examples:** - `{%- tag -%}` removes whitespace on both sides - `{%- tag %}` removes left-side whitespace only - `{% tag -%}` removes right-side whitespace only This technique prevents unwanted blank lines in rendered output while maintaining code readability.