How to Implement Case-Insensitive Sorting in Cloud Firestore?

Cloud Firestore: Achieving Case-Insensitive Sorting Using Query

In Cloud Firestore, sorting data using the OrderBy() function is case-sensitive, resulting in the order of strings based on their case, as demonstrated in the example provided. However, there may be scenarios where case-insensitive sorting is preferred.

Limitations of Case-insensitive Sorting

Firestore does not provide a direct solution for case-insensitive sorting using queries. This is because the sorting and filtering operations are conducted internally by the database, which operates on the actual data stored.

Workaround: Storing Duplicate Fields

The recommended approach to achieve case-insensitive sorting is to store the data twice:

• Original Case: Store the data in its original case, ensuring data integrity and precision.
• Case-insensitive: Store an additional field with the same data converted to a case-insensitive format, such as lowercase.

For instance, consider a field named "myData" with values "AAA" and "aaa". To achieve case-insensitive sorting, create an additional field "myData_insensitive" and store values as "AAA" for both.

Querying and Displaying Data

When performing queries and sorting, specify the "myData_insensitive" field. This ensures that the order will be based on the case-insensitive version of the data. However, when displaying the results, refer to the original "myData" field to maintain data accuracy.

Unicode Considerations

Case normalization is essential when implementing case-insensitive sorting to handle Unicode characters correctly. This involves converting characters to a normalized format, ensuring consistent sorting for strings containing accents and special characters. Different approaches can be used for normalization, such as case folding.

Implementation Example

The following JavaScript code demonstrates how to achieve case-insensitive sorting using duplicate fields:

<code class="javascript">firestore.collection("cities").where("myData_insensitive", ">=", "AAA").where("myData_insensitive", "<=", "aaa").orderBy("myData_insensitive")</code>

This query will return "AAA" and "aaa" in case-insensitive order.

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