TL;DR: Load your data once and use GroupBy to organize it in memory for dependent filters, avoiding repeated data-source queries.
💡 Challenge
Reloading the same data source repeatedly for different dependent filters, like categories and subcategories in dropdowns or combo boxes, hurts your app’s performance.
✅ Solution
Use the GroupBy function to load all your data once, then organize it for each dependent filter in memory instead of querying the source again.
🔧 How It’s Done
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Load all your data, categories, subcategories, and so on, in a single operation.
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Use GroupBy to organize that data according to your filtering needs, so each dependent filter reads from the grouped collection.
🎉 Result
Your app responds faster: less repeated data loading means quicker responses and smoother interactions.
🌟 Key Advantages
🔸 No repeated loads: Load once, reuse for every dependent filter.
🔸 Simpler dependent filters: Managing dependent dropdowns becomes straightforward.
🔸 Cleaner data structure: Your app’s data handling stays streamlined and organized.
ℹ️ Note: GroupBy doesn’t delegate to most data sources, so plan for delegation limits when working with very large datasets.
🎥 Video Tutorial
🛠️ FAQ
1. Can GroupBy handle large datasets efficiently?
Yes, GroupBy is designed to handle large datasets efficiently, but consider data source limitations and delegation when working with very large collections.
2. What happens if my grouping field has null or empty values?
Items with null or empty grouping values will be grouped together under a single group, typically shown as a blank group.
3. Can I group by multiple fields simultaneously?
You can concatenate multiple fields or use nested GroupBy operations, though single-field grouping is more performant and easier to manage.
Marcel Lehmann
Microsoft MVP