Run the plugin, use WPS server with "application/gml+xml" input.
The plugin can handle "text/xml" mime type or "application/gml+xml", but not both: for one or another case the plugin raises "The process '<...>' does not seem to support GML for the parameter '<...>', which is required by the QGIS WPS client." error. (Details depend on order of mime types in VECTOR_MIMETYPES list).
Function getBaseMimeType returns FIRST mime-type of general DATATYPE (== GML in this example)
Function getDataTypeInfo matches mime type of the input and mime type of the stored format.
So if "application/gml+xml" is the first synonym of GML format stored in VECTOR_MIMETYPES list, function getBaseMimeType returns 'application/gml+xml'. But if WPS server provides "text/xml" synonym for GML format, then getDataTypeInfo function doesn't match "text/xml" and "application/gml+xml". As result it returns None, but not dataType.
General description
Some data formats have synonyms, for example "text/xml" mime type has "application/gml+xml" official synonym.
But if a user add new synonym to format list, the resulting code has side effects. For example
VECTOR_MIMETYPES
list).Cause of the issue
The cause is connected with getBaseMimeType and getDataTypeInfo functions (both functions are called in the line):
getBaseMimeType
returns FIRST mime-type of general DATATYPE (== GML in this example)getDataTypeInfo
matches mime type of the input and mime type of the stored format. So if "application/gml+xml" is the first synonym of GML format stored inVECTOR_MIMETYPES
list, functiongetBaseMimeType
returns 'application/gml+xml'. But if WPS server provides "text/xml" synonym for GML format, thengetDataTypeInfo
function doesn't match "text/xml" and "application/gml+xml". As result it returns None, but not dataType.