How to validate substring using regex [closed] - regex

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I am trying to validate whether my API header is in PascalCase or not, for this, I am using the following regex:
^([A-Z][a-z]*)(-[A-Z0-9][a-z0-9]*)*$
I have a use case where the API contains some keywords that are not in PascalCase and I have to ignore this while validating the header, for example:
X-CUSAPI-Trace-Id While using the above regex I want to ignore the X-CUSAPI- part and then apply the validation on Trace-Id.
I am trying with the following regex but it is not working.
^(?!.*X-CUSAPI-).([A-Z][a-z]*)(-[A-Z0-9][a-z0-9]*)*$
Adding example of API specification:
{
"in": "header",
"name": "X-CUSAPI-Trace-Id",
"description": "TraceID",
"required": false,
"schema": {
"type": "string"
}
}
Spotlight spectral tool which help to parse the JSON and find the name for me to apply the regex to validate either it is PascalCase or not:
header-should-pascal-case:
message: "Request and Response HTTP Header should be pascal-case, separated by hyphens Example: PascalCase-Header"
description: SHOULD prefer hyphenated-pascal-case for HTTP header fields
severity: error
given: $.paths.*.*.parameters[?(#.in=='header')].name
then:
function: pattern
functionOptions:
match: ^.*?(?:X-CUSAPI-)?((?:[A-Z][a-z]+)+(?:-(?:[A-Z0-9][a-z0-9]+)+))\b

Answer 1

The issue with the regex you are using is that the negative lookahead assertion is not correctly placed. You can modify your regex to achieve the desired result by placing the negative lookahead assertion before the beginning of the string anchor (^), like this:
^(?!.X-CUSAPI-)([A-Z][a-z])(-[A-Z0-9][a-z0-9])$
This will ignore any string that contains "X-CUSAPI-" anywhere in it, and then match the remaining string using the PascalCase validation pattern.