constant.md

title	perex	date	author	proofreading	preferredLang
Constant ordering	There are situations when the order of entities is specified outside evitaDB. The constant order constraints allow to control the order of the selected entities by a caller logic.	17.1.2023	Ing. Jan Novotný	needed	evitaql

The constant ordering constraints are particularly useful when you have a sorted set of unique attributes or directly the entity primary keys provided by an external system that needs to be maintained in the evitaDB output (for example, it represents a relevance of those entities from the full-text engine).

Exact entity primary key order used in filter

entityPrimaryKeyInFilter()

The constraint allows output entities to be sorted by primary key values in the exact order used to filter them. The constraint requires the presence of exactly one entityPrimaryKeyInSet constraint in the filter part of the query. It uses the specified array of entity primary keys to sort the result returned by the query.

Entities sorted by order of the filtered primary keys

The sample query returns exactly 4 products, which maintain the order of the filtered primary keys in the query that was issued.

List of products sorted by order of entity primary keys in filter

Entities sorted by order of the filtered primary keys

Entities sorted by order of the filtered primary keys

Entities sorted by order of the filtered primary keys

Exact entity primary key order

entityPrimaryKeyExact(
    argument:int+
)

argument:int+

a mandatory set of entity primary keys that control the order of the query result

The constraint allows output entities to be sorted by entity primary keys in the exact order specified in the 2nd through Nth arguments of this constraint.

Entities sorted by the specified order of the primary keys

The sample query returns all products whose code starts with the string lenovo, but uses the order of the first three entities in the output as specified by the order constraint entityPrimaryKeyExact. Because the query returns more results than the order constraint has information for, the rest of the result set is sorted traditionally by the entity primary key in ascending order. If there is another order constraint in the chain, it would be used to sort the rest of the query result.

List of products sorted by the exact order of entity primary keys

Entities sorted by the specified order of the primary keys

Entities sorted by the specified order of the primary keys

Entities sorted by the specified order of the primary keys

Exact entity attribute value order used in filter

attributeSetInFilter(
    argument:string!
)

argument:string!

a mandatory name of the [attribute name](../../use/schema.md#attributes) that control the order of the query result

This constraint allows output entities to be sorted by values of the specified attribute in the exact order in which they were filtered. The constraint requires the presence of exactly one attribute-in-set in the filter part of the query, referring to the attribute with the same name as used in the first argument of this constraint. It uses the specified array of attribute values to sort the result returned by the query.

Entities sorted by order code attribute of the filtered entities

The sample query returns exactly 3 products, preserving the order of the entity's code attribute used in the filter constraint of the query that was issued.

List of products sorted by order of attribute code in filter

Entities sorted by order code attribute of the filtered entities

Entities sorted by order code attribute of the filtered entities

Entities sorted by order code attribute of the filtered entities

Exact entity attribute value order

attributeSetExact(
    argument:string!,
    argument:comparable+
)

argument:string!

a mandatory name of the [attribute name](../../use/schema.md#attributes) that control the order of the query result

argument:comparable+

a mandatory set of attribute values whose data type matches [attribute data type](../../use/schema.md#attributes), which define the order of the query result

The constraint allows output entities to be sorted by attribute values in the exact order specified in the 2nd through Nth arguments of this constraint.

Entities sorted by the specified order of the attribute code values

The sample query returns all products whose code starts with the string lenovo, but uses the order of the first three entities in the output as specified by the order constraint attributeSetExact. Because the query returns more results than the order constraint has information for, the rest of the result set is sorted traditionally by the entity primary key in ascending order. If there is another order constraint in the chain, it would be used to sort the rest of the query result.

List of products sorted by the exact order of entity attribute code

Entities sorted by the specified order of the attribute code values

Entities sorted by the specified order of the attribute code values

Entities sorted by the specified order of the attribute code values