Sorting strings based on the integer value they represent in hibernate search - hibernate-search

Question

I have an entity with a string field in it.
Sometimes this string field stores actual words, so sorting based on lexicographical order makes sense. However, there is a use case where this field stores string values like "0%", "10%", "100%", "20%".
The default string sorting generates the following sequence: 0% 10% 100% 20%.
The ideal sequence after sorting would be 0%, 10%, 20%, 100%(determined by the percentage they represent).
It is guaranteed that there is no mixed data, i.e, you won't have "10%" and "word" appear in the same sequence that needs to be sorted.
My question is if there is a way to achieve the string sorting based on the numerical value they represent?

Answer 1

Ideally, you should alter your model to have two fields: one of integer type where you'll hold the percentage, and one of string type where you will hold the string value:
#Entity
#Indexed
public class MyEntity {
#Field
#SortableField
private int percentage;
#Field
#SortableField
private String notPercentage;
// ... other properties, getters and setters ...
}
Then when sorting you'll just sort on both fields. Since you are certain they are mutually exclusive, it's not a problem to sort on both:
QueryBuilder queryBuilder = ...;
FullTextQuery ftQuery = ...;
ftQuery.sort(queryBuilder.sort().byField("percentage").andByField("notPercentage").createSort());
Alternatively, if you really want to keep a single String property in your ORM model (to each his own...), you can use a custom bridge to apply padding to your values, so that they are sorted correctly:
#Entity
#Indexed
public class MyEntity {
#Field(bridge = #FieldBridge(impl = PaddingIfPercentageBridge.class))
#SortableField
private String percentageOrNot;
// ... other properties, getters and setters ...
}
public class PaddingIfPercentageBridge implements TwoWayStringBridge {
private static final Pattern PERCENTAGE = Pattern.compile("[0-9]+%");
#Override
public String objectToString(Object object) {
if ( object == null ) {
return null;
}
String string = (String) object;
if ( !PERCENTAGE.matcher( string ).matches() ) {
return string;
}
StringBuilder paddedPercentage = new StringBuilder();
for ( int padIndex = string.length(); padIndex < 4; padIndex++ ) {
paddedPercentage.append( '0' );
}
return paddedPercentage.append( string ).toString();
}
#Override
public Object stringToObject(String stringValue) {
// Ideally you should remove the padding here...
return stringValue;
}
}
Then you can sort on a single field:
QueryBuilder queryBuilder = ...;
FullTextQuery ftQuery = ...;
ftQuery.sort(queryBuilder.sort().byField("percentageOrNot").createSort());