How Can I Achieve Case-Insensitive Sorting in Cloud Firestore?

Cloud Firestore Case-Insensitive Sorting with Query

Cloud Firestore requires both queries and filters to be case-sensitive, leaving developers to seek alternative approaches for case-insensitive sorting. To address this, a popular technique involves creating duplicate fields while maintaining case-insensitive copies of the data.

Creating a Case-Insensitive Field

By creating a secondary field with a lowercase version of the original data, sorting and filtering can be performed based on this case-insensitive field. For example, a field called myData could have a corresponding myData_insensitive field with all values converted to lowercase.

DocA:
-> myData = 'AAA'
-> myData_insensitive = 'aaa'

DocB:
-> myData = 'aaa'
-> myData_insensitive = 'aaa'

DocC:
-> myData = 'BBB'
-> myData_insensitive = 'bbb'

DocD:
-> myData = 'bbb'
-> myData_insensitive = 'bbb'

Case-Folding for Unicode

Case-folding is recommended for Unicode support, as it handles complex character normalization and case-insensitive sorting. The following JavaScript snippet provides an example of how to implement case-folding:

<code class="javascript">caseFoldNormalize = function (s){
  return s.normalize('NFKC').toLowerCase().toUpperCase().toLowerCase()
};</code>

Sample Code

This code snippet demonstrates how to create a Firestore document with case-insensitive fields:

<code class="javascript">var raw_document = {
  name: "Los Angeles",
  state: "CA",
  country: "USA",
  structure: 'Waſſerſchloß',
  message: 'quıt quit' // Notice the different i's
};

var field_options = {
  name: 'case_fold',
  country: 'case_fold',
  structure: 'case_fold',
  message: 'case_fold'
}

var firestore_document = caseFoldDoc(raw_document, field_options);

db.collection("cities").doc("LA").set(firestore_document).then(function() {
  console.log("Document successfully written!");
}).catch(function(error) {
  console.error("Error writing document: ", error);
});</code>

This will result in a document with both case-sensitive and case-insensitive fields:

<code class="javascript">{ 
 "name": "Los Angeles", 
 "state": "CA", 
 "country": "USA", 
 "structure": "Waſſerſchloß", 
 "message": "quıt quit", 
 "name_casefold": "los angeles", 
 "country_casefold": "usa", 
 "structure_casefold": "wasserschloss", 
 "message_casefold": "quit quit"
}</code>

Remember, while this technique offers a solution for case-insensitive sorting in Firestore, it requires extra storage space and incurs processing costs for every document update. As with any solution, consider the trade-offs and choose the approach that best aligns with your application requirements.

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