How do I go about successfully querying data from a supabase table using a value passed from a previous page?

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01-09-2024

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Successfully Querying Data from a Supabase Table Using Values Passed from a Previous Page in Flutter

This article explores how to seamlessly query data from a Supabase table using values passed from a previous page in a Flutter application. We'll break down the code, analyze potential issues, and provide solutions to ensure successful data retrieval.

Understanding the Problem

The provided code snippet demonstrates a common scenario in mobile app development:

1. Search Page: The user inputs a search term (location in this case) on the SearchSalePage.
2. Results Page: The entered term is passed to the SaleSearchResultScreen to display relevant listings fetched from Supabase.

The challenge lies in effectively querying the Supabase database using the passed search term to retrieve the correct listings.

Analyzing the Code

Let's examine the provided code for potential issues:

search_sale_tab.dart

• Autocomplete: The search field uses a static list of locations (_list) for autocomplete suggestions. This approach is not dynamic and relies on pre-defined data, making it less flexible.
• Navigation: The SaleSearchResultScreen is navigated to using Navigator.push, correctly passing the selected search term (result) as an argument.

search_sale_results.dart

• Supabase Query: The _fetchData function queries the property_for_sale table using the ilike operator, which performs case-insensitive partial matching. This is the core part of the data retrieval. However, there is a key potential issue: the searchTerm is appended to a % symbol on both ends of the string (%searchTerm%) for the ilike query. This approach may not always work as intended.

The Supabase Query Issue

The issue lies in the way the searchTerm is incorporated into the ilike query. Using %searchTerm% might not effectively match against the database column. For example, searching for "Kitwe" might not return results if the database column contains "Kitwe, Zambia" because the % symbols enforce the entire word to be found, not just parts.

Solution: Refining the Supabase Query

The most common way to use the ilike operator effectively is to apply it to a column containing the complete address or a concatenated string of relevant fields, such as city, suburb, and street name. Here's a refined approach:

1. Database Design: Ensure you have a column (or a calculated field) in your property_for_sale table that combines all relevant address information for searching (e.g., a search_address column).

2. Query Modification: Modify the _fetchData function to use the search_address column:

   Future<List<dynamic>> _fetchData(String searchTerm) async {
       final response = await Supabase.instance.client
           .from('property_for_sale')
           .select()
           .ilike('search_address', '%$searchTerm%'); // Querying the correct column
   
       if (response == null) {
           throw Exception('Failed to load data');
       }
   
       return response as List<dynamic>;
   }
   

Additional Enhancements

• Autocomplete Functionality: Instead of using a static list for autocomplete, integrate Supabase into the search page. This can be achieved using Supabase's rpc functions or by fetching data on demand.
• Error Handling: Implement more robust error handling in the _fetchData function to catch potential exceptions gracefully and display informative messages to the user.

Conclusion

By understanding the nuances of Supabase queries and refining the database design, you can ensure successful data retrieval from Supabase using values passed from a previous page. Remember to pay close attention to the column names and query structure. These optimizations will improve the user experience and make your Flutter application more responsive and efficient.

Note: This article provides a basic understanding of the concept. For specific implementation details, refer to Supabase documentation and Flutter documentation. You can also consult Stack Overflow for more detailed examples and solutions tailored to your specific requirements.