Step 1: Set Up Your Environment and API Access. Ensure your Google Apps Script project is linked to a Google Sheet. If using Gemini, enable the Vertex AI Advanced Service (as covered in Chapter 3) or ensure your OpenAI API key is securely stored in Script Properties (Chapter 2).
Step 2: Create a Core LLM Interaction Function. Write a generic Apps Script function (e.g., callLLM(promptText)) that sends a request to your chosen LLM (Gemini or OpenAI) and returns its response. This function will encapsulate the UrlFetchApp logic and API key handling.
Step 3: Design Specific Prompt Templates for Extraction. Craft precise prompts that instruct the LLM on what to extract and in what format. For example: "Extract the customer name, email address, and product purchased from the following text, and return the data as a JSON object: [text]."
Step 4: Design Specific Prompt Templates for Summarization/Categorization. Create prompts like: "Summarize the following customer review in one concise sentence: [text]" or "Categorize the following support ticket into one of: 'Billing', 'Technical Support', 'Feature Request', 'General Inquiry': [text]."
Step 5: Develop Custom Google Sheet Functions. Create Apps Script functions that can be called directly from your spreadsheet, e.g., =AI_EXTRACT(cellReference, 'json'), =AI_SUMMARIZE(cellReference). These functions will take a cell's content, pass it to your callLLM function with the appropriate prompt, and return the processed result.
Step 6: Implement Response Parsing and Error Handling. For extraction tasks returning JSON, use JSON.parse() to convert the string into a JavaScript object. Implement try-catch blocks to gracefully handle API errors, rate limits, or malformed LLM responses.
Step 7: Apply the Custom Functions in Google Sheets. In your Google Sheet, use your newly created custom functions across relevant columns. For example, if column A contains unstructured text, you might put =AI_EXTRACT(A2, "name") in B2, =AI_EXTRACT(A2, "email") in C2, and drag down.
Step 8: Review and Refine. Manually review a sample of the AI-processed data for accuracy. Adjust your prompt templates as needed to improve extraction quality and consistency.