Building a Robust Blog Listing in HubSpot: From Common Pitfalls to Best Practices

Creating a dynamic and user-friendly blog listing page is a cornerstone of any effective content strategy. For HubSpot users, this often involves a blend of HubL for data retrieval and JavaScript for interactive filtering and pagination. While powerful, this combination can introduce challenges, from frustrating syntax errors to performance bottlenecks.

This article delves into the evolution of a HubSpot blog listing module, illustrating how to overcome common hurdles and adopt best practices for a stable, efficient, and maintainable solution.

The Initial Challenge: A Promising Start, But Room for Improvement

Let's consider a common scenario: a developer starts with a HubSpot module designed to pull recent blog posts, categorize them by custom "content types" (often defined in a separate data source), and allow users to filter by these types and standard blog tags. Pagination is also a key requirement for managing large volumes of content.¹

An early iteration of such a module might look something like the starting point of our discussion:

• HubL for Data Fetching: blog_recent_posts is used to retrieve posts.² Custom content types are linked via a field likecontent.widgets.Custom_Blog_filter.body.Type_Group, which references another data source (e.g., a HubDB table or a custom module field).

• JavaScript for Interactivity: The postInfo array, populated by HubL, is passed to JavaScript. This script then handles rendering the posts, applying filters based on checkbox selections, and managing pagination.

• HTML <template> for Structure: A <template> tag provides the blueprint for each blog post item, which JavaScript clones and populates.

While functional, this initial setup often leads to a few common issues:

1. HubL Syntax Errors: Misplaced {% endfor %} tags, especially within complex HTML structures, are notorious for causing "Missing end tag" errors.

2. "Cannot Resolve Property" Errors: These often point to data inconsistencies. A blog post might be missing a custom field, or the referenced data (e.g., a HubDB row) simply doesn't exist for a given ID, leading to null values where properties are expected.

3. Performance Warnings: The hubdb_table_row Trap: Using hubdb_table_row inside a for loop is a major performance anti-pattern. Each call is a separate database query, quickly consuming resource limits and slowing down page load times, particularly with many blog posts or custom types.

4. Inefficient JavaScript Templating: Relying on string replacement ($(placeholder)) in JavaScript to populate templates can be brittle, harder to debug, and potentially introduce Cross-Site Scripting (XSS) vulnerabilities if not handled carefully.

5. localStorage Synchronization Issues: Using localStorage to cache postInfo can lead to stale data if the blog content changes on the backend but the localStorage isn't appropriately invalidated or refreshed.

Towards a Robust Solution: Refinements and Best Practices

Addressing these issues systematically leads to a more resilient and efficient blog listing.

1. HubL: Data Preparation and Efficiency

The core principle here is to prepare all necessary data in HubL and pass it to JavaScript as a single, clean JSON object.

• Fixed endfor Placement: Meticulous attention to closing tags ensures HubL parses correctly. Always double-check nesting and ensure every {% for %} has a matching {% endfor %}.

• Pre-fetching Content Type Data (Crucial Optimization):

  • If module.content_type_db IS HubDB: Instead of hubdb_table_row in a loop, collect all unique content type IDs first. Then, use the batched hubdb_table_rows(table_id, "id__in=" ~ all_ids|join(",")) function to fetch all relevant rows in one go. Store these in a HubL dictionary (map) for quick lookups within your main blog post loop. This dramatically reduces database calls.

  • If module.content_type_db IS NOT HubDB (e.g., a Repeater Field): Directly iterate over module.content_type_db (if it's an array of objects) and create a map (content_type_map) where keys are IDs and values are names. This allows for content_type_map[id] lookups within the blog post loop, avoiding repeated searches through the array.

• Robust Property Access with |default(''): For any property that might be null or missing (content.name, content.absolute_url, image URLs), always use the |default('') filter. This ensures that even if data is missing, the corresponding JavaScript properties receive an empty string rather than null or undefined, preventing "Cannot resolve property" errors.

• Estimating Reading Time: A simple (initialPostWords / 200)|round(0, "ceil") provides a reasonable estimate, improving user experience.

• Direct JSON Injection: Instead of relying on localStorage for the primary data, directly inject the all_posts_data HubL variable as a JSON object into a JavaScript constant: const ALL_BLOG_POSTS = {{ all_posts_data|tojson }};. This eliminates synchronization concerns and provides a consistent data source on every page load.

2. JavaScript: Dynamic Rendering and Filtering

With a clean data source, JavaScript can focus purely on presentation and interaction.

• DOM-Centric Templating with <template> and data-js-* attributes:

  • Instead of $(placeholder) string replacement, use data-js-* attributes in your <template> HTML.

  • In JavaScript, clone the template's content using document.importNode(template.content, true).

  • Then, use querySelector('[data-js-attribute]') to target specific elements within the cloned fragment and set their properties (textContent, src, href, innerHTML for dynamic HTML like tags/types).

  • Benefits: This approach is more robust, less prone to errors from string manipulation, and significantly reduces the risk of XSS vulnerabilities by using textContent for safe text insertion.

• Clear Filter Logic:

  • Handle the "All" checkbox explicitly: when "All" is checked, uncheck others in its group; when another is checked, uncheck "All."

  • Centralize the getFilteredPosts() function, which reads the current state of checkboxes and returns the subset of posts.

• Dynamic Filter Tag Display: Show selected filters with a "remove" option, providing clear feedback to the user and an easy way to clear individual filters.

• Efficient Pagination:

  • The renderPagination function dynamically creates buttons, including "Previous," "Next," and ellipses, ensuring a clean and functional pagination interface.

  • Crucially, currentPage is reset to 1 Whenever filters change, it prevents users from landing on an empty page after applying a filter that reduces the total post count.

• Loader Experience: The subtle loader animation provides visual feedback while the posts are being dynamically rendered, improving perceived performance.

Conclusion

Building a sophisticated blog listing in HubSpot requires careful attention to both HubL data preparation and JavaScript rendering. By moving away from older, less efficient patterns and embracing practices like batch data fetching (or efficient in-module lookups), direct JSON injection, and DOM-centric templating, developers can create blog listing experiences that are not only highly functional and user-friendly but also stable, performant, and easy to maintain in the long run. These best practices transform a potentially error-prone process into a robust and reliable feature for any HubSpot website.