allow regex comparison operator. Included test cases.

[Yashesh123]

Hi,

This is my first PR to this repository.

This PR will add support for regular expression based filtering. For that I have added a field operator using "matches" provided by neo4j-cypher-dsl. Which will convert to its equivalent cypher regexp operator (~=).

So for this schema:

enum Gender { female, male }
type Person {
id : ID!
name: String
age: Int
height: Float
fun: Boolean
gender: Gender
company: Company @relation(name:"WORKS_AT")
location: _Neo4jPoint
}
type Company {
_id: ID
name: String
employees: [Person] @relation(name:"WORKS_AT", direction: IN)
}
type Query {
person : [Person]
}

This graphql query example will work:

{
person(filter: { name_matches: "Ja.*" }) {
name
}
}

This can be example output:

{
"person" : [ {
"name" : "Jane"
} ]
}

This can also solves requirement for case-insensitiveness as cypher queries are already supporting it using a same (~=) regexp operator.

[Andy2003]

I would suggest to call it MATCHES, since its only usage is for the Cypher parameters. This would make the code more readable.

[Yashesh123]

Done. Thanks, @Andy2003