Basic Filtering

Filter data using conditions with addCondition(). The foundation of dcupl queries - add conditions to narrow down results based on field values, types, and boolean logic.

Syntax

Parameters

Parameter	Type	Required	Description
`attribute`	`string`	Yes	The property to filter on (supports dot notation for deep queries)
`operator`	`Operator`	Yes	Comparison operator: eq, typeof, isTruthy, size (see other pages for find, gt/gte/lt/lte)
`value`	`any`	Yes	Value to compare against. Type depends on operator.
`options.transform`	`('lowercase' \| 'trim' \| 'removeWhitespace')[]`	No	Transform both attribute and search value before comparison
`options.invert`	`boolean`	No	Negate the operator result (NOT logic)
`options.arrayValueHandling`	`'some' \| 'every'`	No	For array attributes: 'some' matches any element (default), 'every' requires all match

Return Type

Returns void. Query state is updated internally. Call items() to get results.

Usage Notes

Queries are chainable - call addCondition() multiple times
Default behavior: multiple conditions use AND logic
Use eq for exact matches, isTruthy for boolean-like checks
typeof is useful for data validation (finding missing/invalid data)
Use options.invert to negate any operator (eq + invert = 'not equal')
Transform option applies to BOTH the data value and your search value
For text search, see Query Search. For ranges, see Query Range.

Related Methods

Query Search - Text search with find operator
Query Range - Numeric/date range filtering
Query Logic - AND/OR combinations
Query Results - Get results with sort/pagination

Examples

Filter by Category

Find all products in a specific category using exact match.

Filter Active Products

Find products that are currently active using boolean filter.

Check In-Stock Items

Use isTruthy to find items with truthy stock values (> 0, true, etc.).

Validate Data Types

Find products where price is actually a number (data validation).

Find Missing Data

Find products without a description (data quality check).

Exclude Values with Invert

Find all products except discontinued ones using invert option.

Case-Insensitive Match

Match brand name regardless of case using transform option.

Filter Array Values

Find products tagged with "featured" using array value handling.

Multiple Conditions (AND)

Combine multiple filters - all must match (AND logic).

Array of Conditions

Pass multiple conditions as an array for cleaner code.