HI all, I’ve had an interesting problem trying to perform an UPDATE based on the results of processing an xpath against a field of type xml. Specifically, my query would fail with:
I thought this strange, since the xml type is (I believe) supposed to guarantee that the value is well formed (wether it’s a document or content). After some amount of digging to locate the rogue entry, it turns out the field value is actually a single whitespace character – which apparently is well formed.. Thus I’m left with the following situation… clone=# select xml_is_well_formed(' '); xml_is_well_formed -------------------- t (1 row) clone=# select xpath_exists (‘//test', ' '); ERROR: could not parse XML document DETAIL: line 1: Start tag expected, '<' not found clone=# create temp table xml_test (document xml); CREATE TABLE clone=# insert into xml_test values (' '); INSERT 0 1 clone=# select xml_is_well_formed(document::text) from xml_test; xml_is_well_formed -------------------- t (1 row) clone=# select xpath_exists ('test', document) from xml_test; ERROR: could not parse XML document DETAIL: line 1: Start tag expected, '<' not found This is confusing, since… if the xml is well formed – it probably shouldn’t cause the parser to error. And if it isn’t well formed, then the instantiation of the value as an xml type should fail. |
