Question

I have a list of objects which contain one XML String field. I have to execute an SQL like query for that field, and get a sub list that satisfies the values. I am trying to use XPath.

Firstly, I can’t figure out the XPath string to achieve this. Secondly, there might be a better way of doing this. I tried searching through SO but the answers don’t really address this problem

Details

I have a list of books:

List <Books> allBooks;

The Book class can have an id and details fields. The details is XML.

class Book
{
    String id;
    String details; //XML
}

Here is a sample of the details xml String:

<book>
   <name>Harry Potter and the sorcerer's stone</name>
   <author>J K Rowling</author>
   <genre>fantasy</genre>
   <keyword>wizard</keyword>
   <keyword>british</keyword>
   <keyword>hogwarts</keyword>
   <price>25</price>
</book>

So, uptil here it is all set in stone. It is part of existing code and I cannot change that design.

My work is to take the list allBooks & run a query through it, the logic of which is:

   WHERE author = "J K Rowling" AND
     genre = "fantasy" AND
     (keyword = "wizard" OR keyword="hogwarts")

I considered throwing this data in a DB to run an actual query, but since the list will only contain a couple of hundred records, the overhead of connection, loading data etc is not worth it.

Anyone know how to do this through XPath? Any better way of doing this?

Answer 1

We need book records

//book

with author “J K Rowling”

//book[author = "J K Rowling"]

and genre is “fantasy”

//book[author = "J K Rowling" and genre = "fantasy"]

and keyword is “wizard” or “hogwarts”

//book[author = "J K Rowling" and genre = "fantasy" and (keyword = "wizard" or keyword = "hogwarts")]