How to map Json object to JPA specification for Search query - jpa

Question

I have a RequestMaping that get a Search json class as body params.
I want to create proper Specification from this search json object so that pass to my Repository like this:
pagesResult = myRepository.findAll(mySpec)
I have problme with parsing and Dynamically add items to specification. I want to achieve something like this:
#Override
public Phones searchPhones(int pageNumber, Map<String, String> searchObject) {
List<PhoneSpecification> specificationslist = new ArrayList<>();
generateSpecifications(searchObject, specificationslist); //fill specificationList
Specification<Phone> specificationOfPhone;
for (PhoneSpecification spec :
specificationslist) {
//this is my problem , I had to dynamically increase my Specification like this:
specificationOfPhone = specificationOfPhone + Specifications.and(spec);
}
mobileRepository.findAll(specificationOfPhone);

Answer 1

I finally achieve this by adding where to first specification and handle all by adding like this:
if(specificationslist.size()>0){
finalSpecification = Specifications.where(specificationslist.get(0)) ;
}
for (int i=1 ; i<specificationslist.size(); i++) {
finalSpecification = Specifications.where(finalSpecification).and(specificationslist.get(i));
}

Answer 2

You can change your code to this:
Specifications<Phone> specificationOfPhone = Specifications.where(null);
for (PhoneSpecification spec : specificationslist) {
specificationOfPhone = specificationOfPhone.and(spec);
}
I assumed that PhoneSpecification is extending/implements Specification<T>.
Specifications.where(null); will return empty specification which can be chained with others.
Because Specifications<T> extends Specification<T> you can use it with your findAll method.