allow passed ZipWriter objectd to write_jsonld, supports USEPA/LCIAfo…

…rmatter#103

fedelemflowlist/__init__.py

@@ -66,7 +66,7 @@ def get_flowmapping(source=None):
     return flowmappings
 
 
-def write_jsonld(flows, path: Path, mappings=None):
+def write_jsonld(flows, path: Path, mappings=None, **kwargs):
     """ Writes a standard openLCA JSON-LD zip archive with elementary flows and optionally
      flowmappings
 
@@ -76,7 +76,7 @@ def write_jsonld(flows, path: Path, mappings=None):
     :return: writes out .zip file
     """
     writer = jsonld.Writer(flow_list=flows, flow_mapping=mappings)
-    writer.write_to(path)
+    writer.write_to(path, zw=kwargs.get('zw'))
 
 def get_alt_conversion():
     """returns a dataframe of all flowables with altunits and alt conversion factors

fedelemflowlist/jsonld.py

@@ -130,20 +130,26 @@ def __init__(self, flow_list: pd.DataFrame,
         self.flow_mapping = flow_mapping
         self._context_uids = {}
 
-    def write_to(self, path: Path):
+    def write_to(self, path: Path, zw: zipio.ZipWriter = None):
         """
         Writes json dictionaries to files
         :param path: string path to file
+        :param zw: optional zipio.ZipWriter
         :return: None
         """
-        if path.exists():
+        if (path and path.exists()):
             log.warning(f'File {path} already exists and will be overwritten')
             path.unlink()
-        zw = zipio.ZipWriter(path)
+        if not zw:
+            passed_zw = False
+            zw = zipio.ZipWriter(path)
+        else:
+            passed_zw = True
         self._write_flows(zw)
         if self.flow_mapping is not None:
             self._write_mappings(zw)
-        zw.close()
+        if not passed_zw:
+            zw.close()
 
     def _write_flows(self, zw: zipio.ZipWriter):
         altflowlist=fedelemflowlist.get_alt_conversion()