Dashboard Requests: multiple codes are not overwritten in the filter

[tanzm]

Example of Issue: Multiple codes

For the 1st request, the filter contains the purpose codes "1", "2", "3" and "4" and this is reflected correctly as:
filter.parameters.row.purposecode.codes.codes = ["1", "2", "3", "4"]

For the 2nd request, the filter now contains only 1 purpose code, let's say "1" and this is reflected incorrectly as:
filter.parameters.row.purposecode.codes.codes = ["1", "2", "3", "4"]

Example of when No Issue arises: Single Code

For the 1st request, the filter contains 1 purpose code, let's say "1" and this is reflected correctly as:
filter.parameters.row.purposecode.codes.codes = ["1"]

For the 2nd request, the filter now contains a different purpose code, let's say "2" and this is reflected correctly as:
filter.parameters.row.purposecode.codes.codes = ["2"]