Filter over Nested Map value's in Spring data mongo query-dsl - mongodb

Question

I am integrating the Spring-Data-mongo with query-dsl, so i need to Generate Q-files for query-dsl queries
Here is my Order POJO:
public class Order {
private List<Map<String,Object>> items;
}
My Q file of Order.java
public class QOrder extends EntityPathBase<Order> {
private static final long serialVersionUID = -682690651L;
public static final QOrder order = new QOrder("order");
public final ListPath<java.util.Map<String, Object>, SimplePath<java.util.Map<String, Object>>> items = this.<java.util.Map<String, Object>, SimplePath<java.util.Map<String, Object>>>createList("items", java.util.Map.class, SimplePath.class, PathInits.DIRECT2);
public QOrder(String variable) {
super(Order.class, forVariable(variable));
}
public QOrder(Path<? extends Order> path) {
super(path.getType(), path.getMetadata());
}
public QOrder(PathMetadata metadata) {
super(Order.class, metadata);
}
}
and sample json's of order is
{
"items": [{
"itemName": "phone",
"quantity": <Integer-Number>
}
]
}
Now i want to retrieve all the order's from mongo for which any Item exist with qunatity 1.
Now i am generating my predicate like below.
"QSensorData.sensorData.data.any().eq(Some-QueryDSL-Expression)".
I am unable to identify what need to pass in eq method for filtering nested map values.

Answer 1

Change Order class to include List attribute where Item contains itemName and quantity fields. Something like
public class Order {
private List<Item> items;
}
public class Item {
private String itemName;
private Integer quantity;
}
Generate Q classes.
Use below query to return all items where there is atleast one item with quantity with 1.
BooleanExpression expression = QOrder.order.items.any().quantity.eq(1);
List<Order> results = repository.findAll(expression);
As noted in the comment to return all filtered items with value 1 you have to use aggregation query.
Something like
Static Imports
import static org.springframework.data.mongodb.core.aggregation.Aggregation.*;
import static org.springframework.data.mongodb.core.aggregation.ArrayOperators.Filter.filter;
import static org.springframework.data.mongodb.core.aggregation.ComparisonOperators.Eq.valueOf;
Aggregation Query
Aggregation aggregation = newAggregation(
project().and(filter("items")
.as("item")
.by(valueOf(
"item.quantity")
.equalToValue(
1)))
.as("items");
);
List<Order> results = mongoTemplate.aggregate(aggregation, Order.class, Order.class)