Content Filtered Topic based on a dynamic parameter string

[ConstantTilt]

I am trying to set up a Content Filtered Topic in such a way that my filter expression is defined as something like expression = "id_string match %0 and through use of set_expression_parameters() I'm able to adjust the %0 parameter to a string resembling "'sys-a, sys-b, sys-c'" or any variation thereof.

For context: I previously had this exact set up working withing RTI's Connext DDS architecture, which also uses and SQL-like filtering mechanism, but I haven't been able to find a way to make it work within FastDDS. As far as I can tell, the "match" operator does not play well (if at all) with a parameter. Maybe I'm wrong or I just haven't concocted the proper expression to make it work in the same way.

I am aware that I can set the filter expression to a series of id_string match %0 or id_string match %1 or .... id_string match %n with a corresponding vector of {"'sys-a'","'sys-b'", "'sys-c'", .... "'sys-n'"} but that's not really feasible for the scale I'm looking to develop for.

Any help/guidance is appreciated, thanks in advance.

[MiguelCompany]

The match operator is not part of the DDS standard filters. Being a non-standard extension, each vendor might implement it differently.

As stated in the documentation, Fast DDS expects the second operand to be a Basic Regular Expression.

For your specific use case, a parameter value like "'^sys-[abc]'" would do the trick.