How to Implement Conditional Filtering in Firestore with Multiple Clauses?

Conditional Filtering in Firestore with Multiple Clauses

Imagine you have a dynamic filtering system for your book collection, allowing users to filter by color, author, and category. To accommodate filters with multiple selections (e.g., "Red, Blue" and "Adventure, Detective"), you need to implement conditional "where" clauses in your Firestore query.

Solution

To conditionally add "where" clauses, you must work with the immutable nature of Query objects in Firestore. Instead of modifying the existing query, create a new Query object for each filter you add:

<code class="javascript">var query = firebase.firestore().collection("book");

// Check for conditions and add filters accordingly
if (colorFilter) {
    query = query.where("color", "==", colorFilter);
}
if (categoryFilter) {
    query = query.where("category", "==", categoryFilter);
}

// Apply sorting if needed
if (orderBy) {
    query = query.orderBy(orderBy.field, orderBy.direction);
}

// Finalize the query and fetch results
query.get().then(...);</code>

By continuously reassigning the query variable with each new filter, you build a chain of conditional queries that dynamically adapt to your filtering criteria.

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