How to transform PageRequest object to query string? - rest

Question

I'm writing an RESTful API which consumes another RESTful Data API, and I'm using Spring Data.
The client side send the page request using query params like:
http://api.mysite.com/products?page=1&size=20&sort=id,asc&sort=name,desc
And I transform the params to PageRequest object and transfer it to the Service Layer.
In the service, I would like to use TestTemplate to interact with the Data API which use a URL, and How can I transform the PageRequest object to a query string like
page=1&size=20&sort=id,asc&sort=name,desc
then I can request data like:
restTemplate.getForEntity("http://data.mysite.com/products?page=1&size=20&sort=id,asc&sort=name,desc",String.class)

Answer 1

I know I am a bit late on this answer, but I too was not able to found an already implemented way to do this. I ended up developing my own routine for doing this:
public static String encodeURLComponent(String component){
try {
return URLEncoder.encode(component, "UTF-8");
} catch (UnsupportedEncodingException e) {
throw new RuntimeException("You are dumm enough that you cannot spell UTF-8, are you?");
}
}
public static String queryStringFromPageable(Pageable p){
StringBuilder ans = new StringBuilder();
ans.append("page=");
ans.append(encodeURLComponent(p.getPageNumber() + ""));
// No sorting
if (p.getSort() == null)
return ans.toString();
// Sorting is specified
for(Sort.Order o : p.getSort()){
ans.append("&sort=");
ans.append(encodeURLComponent(o.getProperty()));
ans.append(",");
ans.append(encodeURLComponent(o.getDirection().name()));
}
return ans.toString();
}
It is not complete, there probably are a couple of details that I am missing, but for my user case (and I think for most of them) this works.

Answer 2

you can pass as new :
new PageRequest(int page,int size)
And in repository layer you can write as:
Page<User> findByName(String name,Pageable page)
in place of Pageable page you have to pass new PageRequest(int page,int size)
For ascending order you can refer this:
List<Todo> findByTitleOrderByTitleAsc(String title);

Answer 3

I think you just need to iterate through the request parameters from your other API request, and then pass all the parameters values into the new Url for a new API request.
sudo code could be:
//all query params can be found in Request.QueryString
var queryParams = Request.QueryString;
private string ParseIntoQuery(NameValueCollection values)
{
//parse the identified parameters into a query string format
// (i.e. return "?paramName=paramValue&paramName2=paramValue2" etc.)
}
in your code, you will then do this:
restTemplate.getForEntity(urlAuthority + ParseIntoQuery(Request.QueryString));
simple as that. Hope that answers?

Answer 4

UriComponentsBuilder uriComponentsBuilder = UriComponentsBuilder.fromHttpUrl("http://data.mysite.com/products");
addRequestParam(uriComponentsBuilder, "page", pageable.getPageNumber());
addRequestParam(uriComponentsBuilder, "size", pageable.getPageSize());
String uri = uriComponentsBuilder.toUriString() + sortToString(pageable.getSort());
addRequestParam method:
private static void addRequestParam(UriComponentsBuilder uriBuilder, String parameterName, Object parameter) {
if (parameter != null) {
uriBuilder.queryParam(parameterName, parameter);
}
}
implement sortToString(Sort sort) method as #Shalen. You have to obtain something like this: &sort=name,asc&sort=name2,desc. Return "" if Sort is null;