Is there any XPath expression for String Padding in wso2 ESB?

Question

I have enabled XPath 2.0 configuration synapse.xpath.dom.failover.enabled=true in synapse.properties but still unable to get string padding done. Is there any expression to achieve it?

Edit :

The length of a particular string needs to be 10 chars, if it is lesser than it, we have to pad it with the special character '%'.

Eg., Input = 'WSO2', after padding it should be 'WSO2%%%%%%'

Thanks in advance

Answer 1

This can be achieved using XPath 1.0 like so, assuming that "WSO2" will be replaced by dynamic input string in the actual implementation :

substring(concat('WSO2', '%%%%%%%%%%'), 1, 10)

The above XPath basically works by concatenating string of 10 specific for-padding characters to the original input string, and then substring the result to get only the first 10 characters. Found this trick in the following XSL question : XSL left-right justification with Padding

To put this in a more generic formula :

substring(concat('input_string', '%%%%....'), 1, n)

• input_string : string to which padding operation will applied
• % : character used for padding, repeated n times
• n : fixed number of characters expected in the output string

Answer 2

The solution from @har07 is fine if you have a reasonable upper bound on the value of n, but if you don't, you can create a string containing '%' repeated $n times using

XPath 3.0: string-join((1 to $n)!"%")

XPath 2.0: string-join(for $x in 1 to $n return "%", "")