Optional parameters in PointSymbolizer href

Question

I am trying to build a dynamic url for a PointSymbolizer:

/api/icons?foo=${strUrlEncode("foo")}&bar=${strUrlEncode("bar")}

The problem I am running into is that the strUrlEncode will return null if the "foo" property is null. When that happens I get the following exception:

DEBUG [function.string] - Failed to concatenate string in Concatenate function
java.lang.NullPointerException
    at java.net.URLEncoder.encode(URLEncoder.java:204)
    at org.geotools.filter.function.string.URLEncodeFunction.evaluate(URLEncodeFunction.java:87)
    at org.geotools.filter.expression.ExpressionAbstract.evaluate(ExpressionAbstract.java:45)
    at org.geotools.filter.function.string.ConcatenateFunction.evaluate(ConcatenateFunction.java:66)
    at org.geotools.filter.expression.ExpressionAbstract.evaluate(ExpressionAbstract.java:45)

I imagine that is happening because the result of my first strUrlEncode (which is null) is being concatenated to the second parameter.

Is there any way I can provide a default non-null value in a case where foo is null to avoid the NPE?

Answer 1

The problem is that the java function URLEncoder.encode() doesn't handle null arguments and the GeoTools function is not checking if the argument is null. You need to add a check before line 87 and return an empty string or "null" if the argument is null.

As always pull requests with a test case are welcome.