Reports admin filter URL encoding issue

[mfendeksilverstripe]

Reports admin URL encoding issue

Affected version: 4.5.1

Reports have the capability to add form filters via the parameterFields() method. These fields will be shown via the Reports admin UI. The values of the filter fields are collected via JavaScript and appended to URL as GET params. This process applies url encoding. The form gets populated by these encoded values which has side effects.

Test scenario

This causes a problem with some characters. Example below shows what happens if string A B is used to filter.

After clicking filter

Expected result

A B filter value is retained

Actual result

A B gets transformed into A+B

Possible solution

Applying urldecode to Form population seems to do the trick.

[emteknetnz]

I made an attempt (now closed) in #134

PR has a useful comment from Max about a more correct way to solve this