如何在QueryDSL中使用按位运算符？

Question

嗨,

public interface RateRepository extends CrudRepository<Rate,RatePK>, QueryDslPredicateExecutor<Rate>, QuerydslBinderCustomizer<QRate> {

@Override
default void customize(QuerydslBindings bindings, QRate qRate) {
    bindings.bind(qRate.rateId).first(
            (path, value) -> {
                return (path & value > 0) //Something like this, or a function like:
                //return (bitwise_AND(path, value) > 0);
            });
}

我还尝试使用com.querydsl.core.types.dsl.expressions和com.querydsl.core.types.predicate，如下所示：

bindings.bind(qRate.rateFlag).first(
            (path, value) -> {
                Expression<Integer> intPath = Expressions.asNumber(path);
                Expression<Integer> rateFlag = Expressions.asNumber(value);
                Expression<Integer> zeroValue = Expressions.asNumber(0);
                Expression<Integer> integerExpression = Expressions.numberOperation(Integer.class, Ops.AND, intPath, rateFlag);
                Predicate predicate  = Expressions.predicate(Ops.GT, integerExpression, zeroValue);
                return predicate;
            });

但我得到了一个无效的运算符和错误。

怎么会这样呢？

Answer 1

首先，您需要扩展hibernate方言以支持位操作，如下所示

public class MySQLDialect extends org.hibernate.dialect.MySQLDialect {

    public MySQLDialect() {
        super();
        registerFunction("bitand", new SQLFunctionTemplate(IntegerType.INSTANCE, "(?1 & ?2)"));
    }
}

然后可以从querydsl或spring存储库中引用此函数

bindings.bind(qRate.rateFlag).first(
            (path, value) -> {
                Expression<Integer> zeroValue = Expressions.asNumber(0);
                NumberTemplate<Integer> numberTemplate = Expressions.numberTemplate(Integer.class, "function('bitand', {0}, {1})", path, value);
                return numberTemplate.gt(0);
            });