How to check null and apply filter in JPA Querydsl?

Question

I have a scenario like below and i am using JPA Query DSL:

List<Student> allStudents(String inputDob){
     List<Student> resultList = jpaQuery.from(student)
                    .where(student.dob.eq(inputDob) //how to skip this condition in case inputdob is null
                    .and(student.age.eq(25)))    
                    .fetch(); 
}
//My question is suppose : inputDob is null then how to skip the where clause if parameter is comming as null?

Answer 1

An if/else statement might work for you.

List<Student> allStudents(String inputDob){
    List<Student> resultList = null;
    if (inputDob == null || inputDob.isEmpty()) {
         resultList = jpaQuery.from(student)
                .where(student.age.eq(25))
                .fetch();
    } else {
        resultList = jpaQuery.from(student)
                .where(student.dob.eq(inputDob)
                        .and(student.age.eq(25)))
                .fetch();
    }
}

You initialize the resultList before the if/else statement, so you can avoid compilation errors later. Then you run the appropriate query, depending on the input.

Please let me know if this was helpful for your case.