Currently front-end not generating the search combination ( (title = "United States" or isbn = "2345371242192") and author ="Jhon" ) just i am thinking, if i could achieve this way, so that i could ask fron-end person to send this way.
If your frontend is JavaScript-based, it may be easier and cleaner to create a JSON object that contains the search fields. Something like:
{ "AND": { "OR": { "isbn" : "2345371242192", "title": "United States" }, "author": "Jhon" } }
If you POST this snippet as 'application/json' to a RESTXQ backend, the resulting XML structure will be:
<json type="object"> <AND type="object"> <OR type="object"> <isbn>2345371242192</isbn> <title>United States</title> </OR> <author>Jhon</author> </AND> </json>
You can then parse this XML fragment with XQuery to either:
a) recursively build a query string, which will be evaluated via xquery:eval (as proposed on StackOverflow), or b) process the query tree recursively for each element of your document.
The first variant will probably be more efficient.
You’ll probably need to invest some time to get this realized (I don’t think there’s a solution that can be used out of the box).
Best, Christian