How to make one condition in filter optional?

[koote]

I have a query structure defined like this:

type queryAccounts struct {
	Accounts []struct {
            ID string        graphql.String `graphql:"id"`   
            Type string    graphql.String `graphql:"type"`    
            Region string  graphql.String `graphql:"region"`
            Owners string  []graphql.String `graphql:"owners"`
        }`graphql:"allAccountsList(filter:{region: {equalTo: $region}, types:{in: $types}})"`
}

The problem is, the filter [types](types:{in: $types}}) is not always needed. Sometimes i want to query with filter like region=west, types=["test","production","preproduction"], sometimes i just want to query with filter region=east.
How to make the filter types optional? thanks.

[koote]

Or, is there a way to pass in a full filter string when query?