How to convert a list of enity object to page object in Spring MVC (JPA)?
Solution 1:
There is a Page
implementation for that:
final Page<Something> page = new PageImpl<>(theListOfSomething);
Solution 2:
There is one more Constructor :
Page<Something> page = new PageImpl<>(listOfsomething, pageable, listOfsomething.size());
Solution 3:
I think you will need to fetch the correct page content as well.
PageRequest pageRequest = PageRequest.of(offset, limit);
List<Product> products = getProducts();
int total = products.size();
int start = toIntExact(pageRequest.getOffset());
int end = Math.min((start + pageRequest.getPageSize()), total);
List<Product> output = new ArrayList<>();
if (start <= end) {
output = products.subList(start, end);
}
return new PageImpl<>(
output,
pageRequest,
total
);
Solution 4:
You can pass a list to the function to make it a pageable object. If the start value of the sublist is less than the list size, it returns the empty content.
public Page<?> toPage(List<?> list, Pageable pageable) {
int start = (int) pageable.getOffset();
int end = Math.min((start + pageable.getPageSize()), list.size());
if(start > list.size())
return new PageImpl<>(new ArrayList<>(), pageable, list.size());
return new PageImpl<>(list.subList(start, end), pageable, list.size());
}
Solution 5:
The above answers all assume the list is what you wish to return. Here is what you can do to perform pagination on a list containing total records.
//pageNum starts with 1
//size: page size
//totalRecords, total records
Page<Record> myMethod(int pageNum, int size, List<MyRecord> totalRecords){
if(pageNum<1){
pageNum = 1;
}
if(size < 1){
size = 10;
}
//spring page starts with 0
Pageable pageable = new PageRequest(pageNum-1, size);
//when pageNum * size is too big(bigger than list.size()), totalRecords.subList() will throw a exception, we need to fix this
if(pageable.getOffset() > list.size()){
pageable = new PageRequest(0, size);
}
List<MyRecord> pageRecords = totalRecords.subList(pageable.getOffset(), Math.min(pageable.getOffset() + pageable.getPageSize(), totalRecords.size()));
Page springPage = new PageImpl<>(pageRecords, pageable, totalRecords.size());
return springPage;
}