Auto-Categorize WordPress Posts with OpenAI

This workflow automates the process of categorizing WordPress blog posts using OpenAI's language model. It fetches all existing posts, analyzes each title to determine the most relevant category from a predefined list, and updates the post with the assigned category ID. This saves hours of manual effort and ensures consistent taxonomy across your content library.

Step-by-Step Workflow

1. When clicking ‘Test workflow’ (Manual Trigger) — No auth required. Starts the workflow on demand. Replace with a Schedule Trigger for automated runs.
2. Get All Wordpress Posts (WordPress API) — Uses WordPress credentials (Basic Auth or Application Password). Retrieves all posts from your WordPress site with returnAll: true.
3. OpenAI Chat Model (OpenAI API Key) — Configures the OpenAI language model. Requires a valid OpenAI API key stored in your n8n credentials.
4. AI Agent (No auth) — Processes each post's title using a custom prompt. The prompt defines a fixed category map (e.g., 13 = Content Creation) and instructs the AI to output only the single most relevant category ID. It references $json.title.rendered from the previous node.
5. Wordpress (WordPress API) — Updates the post (operation: update) using the post ID from the 'Get All Wordpress Posts' node and sets the categories field to the output of the AI Agent ($json.output).

Setup Instructions

• WordPress: You need a WordPress site with the REST API enabled. Create an application password or use your username/password for Basic Auth. Store these as a WordPress credential in n8n.
• OpenAI: Sign up for OpenAI and obtain an API key from platform.openai.com/api-keys. Save it as an OpenAI credential in n8n.
• Categories: First ensure the category IDs in the AI prompt match the actual category IDs in your WordPress installation. The workflow uses hardcoded IDs (e.g., 13, 14, 15...). Adjust these as needed.

Use Cases & Customization

• Scheduled categorization: Replace the manual trigger with a Cron or Schedule trigger to run daily/weekly.
• Adapt categories: Modify the prompt to use different category names/IDs, or add more categories.
• Extend analysis: Include post content or excerpt in the prompt for more accurate categorization.
• Export results: Add a node (e.g., Google Sheets) to log which categories were assigned for auditing.
• Bulk re-categorization: Run once to categorize hundreds of existing posts in minutes.

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          "categories": "={{ $json.output }}"
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