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# Query Building & Filters
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Comprehensive query building utilities for creating MongoDB queries, filters, sorts, projections, and updates with type safety and fluent APIs.
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## Capabilities
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### Filters Utility Class
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Factory methods for creating query filters with type-safe field matching.
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```java { .api }
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public final class Filters {
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    // Equality operations
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    public static Bson eq(String fieldName, Object value);
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    public static Bson ne(String fieldName, Object value);
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    // Comparison operations
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    public static Bson gt(String fieldName, Object value);
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    public static Bson gte(String fieldName, Object value);
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    public static Bson lt(String fieldName, Object value);
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    public static Bson lte(String fieldName, Object value);
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    // Array operations
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    public static Bson in(String fieldName, Object... values);
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    public static Bson nin(String fieldName, Object... values);
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    // Logical operations
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    public static Bson and(Bson... filters);
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    public static Bson or(Bson... filters);
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    public static Bson not(Bson filter);
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    public static Bson nor(Bson... filters);
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    // Pattern matching
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    public static Bson regex(String fieldName, String pattern);
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    public static Bson regex(String fieldName, Pattern pattern);
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    // Field existence
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    public static Bson exists(String fieldName);
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    public static Bson exists(String fieldName, boolean exists);
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    // Type checking
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    public static Bson type(String fieldName, BsonType type);
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    public static Bson type(String fieldName, String type);
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}
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```
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### Updates Utility Class
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Factory methods for creating update operations with type safety.
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```java { .api }
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public final class Updates {
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    // Field updates
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    public static Bson set(String fieldName, Object value);
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    public static Bson unset(String fieldName);
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    public static Bson rename(String fieldName, String newFieldName);
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    public static Bson setOnInsert(String fieldName, Object value);
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    // Numeric updates
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    public static Bson inc(String fieldName, Number amount);
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    public static Bson mul(String fieldName, Number amount);
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    public static Bson min(String fieldName, Object value);
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    public static Bson max(String fieldName, Object value);
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    // Array updates
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    public static Bson push(String fieldName, Object value);
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    public static Bson pushEach(String fieldName, List<?> values);
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    public static Bson pull(String fieldName, Object value);
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    public static Bson pullAll(String fieldName, List<?> values);
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    public static Bson addToSet(String fieldName, Object value);
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    public static Bson popFirst(String fieldName);
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    public static Bson popLast(String fieldName);
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    // Combined updates
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    public static Bson combine(Bson... updates);
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}
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```
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### Projections Utility Class
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Factory methods for creating field projections.
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```java { .api }
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public final class Projections {
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    public static Bson include(String... fieldNames);
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    public static Bson exclude(String... fieldNames);
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    public static Bson excludeId();
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    public static Bson elemMatch(String fieldName, Bson filter);
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    public static Bson slice(String fieldName, int limit);
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    public static Bson slice(String fieldName, int skip, int limit);
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    public static Bson textScore(String fieldName);
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    public static Bson meta(String fieldName, String metaFieldName);
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    public static Bson fields(Bson... projections);
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}
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```
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### Sorts Utility Class
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Factory methods for creating sort specifications.
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```java { .api }
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public final class Sorts {
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    public static Bson ascending(String... fieldNames);
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    public static Bson descending(String... fieldNames);
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    public static Bson orderBy(Bson... sorts);
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    public static Bson textScore(String fieldName);
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    public static Bson metaTextScore();
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}
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```
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**Usage Examples:**
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```java
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import com.mongodb.client.model.Filters;
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import com.mongodb.client.model.Updates;
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import com.mongodb.client.model.Projections;
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import com.mongodb.client.model.Sorts;
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// Complex query with filters
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FindIterable<Document> results = collection.find(
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    Filters.and(
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        Filters.gte("age", 18),
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        Filters.lt("age", 65),
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        Filters.in("status", "active", "pending"),
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        Filters.regex("name", "^A.*", "i")
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    )
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);
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// Update operations
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UpdateResult result = collection.updateMany(
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    Filters.eq("department", "Engineering"),
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    Updates.combine(
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        Updates.inc("salary", 5000),
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        Updates.set("lastUpdated", new Date()),
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        Updates.addToSet("skills", "MongoDB")
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    )
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);
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// Projection and sorting
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FindIterable<Document> projected = collection.find()
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    .projection(Projections.fields(
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        Projections.include("name", "email", "department"),
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        Projections.excludeId()
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    ))
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    .sort(Sorts.orderBy(
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        Sorts.ascending("department"),
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        Sorts.descending("salary")
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    ));
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```