Implement support for handling file objects as

input to the freeze function, fixes #79.

dataset/freeze/app.py

@@ -20,9 +20,9 @@ parser.add_argument('--db', default=None,
                     help='Override the freezefile database URI')
 
 
-def freeze(result, format='csv', filename='freeze.csv',
-           prefix='.', meta={}, indent=2, mode='list',
-           wrap=True, callback=None, **kw):
+def freeze(result, format='csv', filename='freeze.csv', fileobj=None,
+           prefix='.', meta={}, indent=2, mode='list', wrap=True,
+           callback=None, **kw):
     """
     Perform a data export of a given result set. This is a very
     flexible exporter, allowing for various output formats, metadata
@@ -34,6 +34,15 @@ def freeze(result, format='csv', filename='freeze.csv',
         result = db['person'].all()
         dataset.freeze(result, format='json', filename='all-persons.json')
 
+    Instead of passing in the file name, you can also pass a file object::
+
+        result = db['person'].all()
+        fh = open('/dev/null', 'wb')
+        dataset.freeze(result, format='json', fileobj=fh)
+
+    Be aware that this will disable file name templating and store all
+    results to the same file.
+
     If ``result`` is a table (rather than a result set), all records in
     the table are exported (as if ``result.all()`` had been called).
 
@@ -50,7 +59,8 @@ def freeze(result, format='csv', filename='freeze.csv',
     is set to *item* the function would generate one file per row. In
     that case you can  use values as placeholders in filenames::
 
-            dataset.freeze(res, mode='item', format='json', filename='item-{{id}}.json')
+            dataset.freeze(res, mode='item', format='json',
+                           filename='item-{{id}}.json')
 
     The following output ``format`` s are supported:
 
@@ -70,6 +80,7 @@ def freeze(result, format='csv', filename='freeze.csv',
     kw.update({
         'format': format,
         'filename': filename,
+        'fileobj': fileobj,
         'prefix': prefix,
         'meta': meta,
         'indent': indent,

dataset/freeze/format/common.py

@@ -1,5 +1,6 @@
 import os
 import re
+import sys
 import locale
 
 try:
@@ -28,8 +29,12 @@ class Serializer(object):
         self._paths = []
         self._get_basepath()
 
+        if export.get('filename') == '-':
+            export['fileobj'] = sys.stdout
+        self.fileobj = export.get('fileobj')
+
     def _get_basepath(self):
-        prefix = self.export.get('prefix')
+        prefix = self.export.get('prefix', '')
         prefix = os.path.abspath(prefix)
         prefix = os.path.realpath(prefix)
         self._prefix = prefix
@@ -49,6 +54,10 @@ class Serializer(object):
         return os.path.realpath(path.encode(enc, 'replace'))
 
     def file_name(self, row):
+        # signal that there is a fileobj available:
+        if self.fileobj is not None:
+            return None
+
         path = self._tmpl(row)
         if path not in self._paths:
             if not path.startswith(self._prefix):
@@ -79,4 +88,5 @@ class Serializer(object):
                 row[field] = OPERATIONS.get(operation)(row.get(field))
 
             self.write(self.file_name(row), row)
+
         self.close()

dataset/freeze/format/fcsv.py

@@ -22,7 +22,13 @@ class CSVSerializer(Serializer):
     def write(self, path, result):
         keys = list(result.keys())
         if path not in self.handles:
-            fh = open(path, 'wb')
+
+            # handle fileobj that has been passed in:
+            if path is not None:
+                fh = open(path, 'wb')
+            else:
+                fh = self.fileobj
+
             writer = csv.writer(fh)
             writer.writerow([k.encode('utf-8') for k in keys])
             self.handles[path] = (writer, fh)

dataset/freeze/format/fjson.py

@@ -36,13 +36,15 @@ class JSONSerializer(Serializer):
     def close(self):
         for path, result in self.buckets.items():
             result = self.wrap(result)
-            fh = open(path, 'wb')
+
+            fh = open(path, 'wb') if self.fileobj is None else self.fileobj
+            
             data = json.dumps(result,
-                    cls=JSONEncoder,
-                    indent=self.export.get_int('indent'))
+                              cls=JSONEncoder,
+                              indent=self.export.get_int('indent'))
             if self.export.get('callback'):
                 data = "%s && %s(%s);" % (self.export.get('callback'),
-                                         self.export.get('callback'),
-                                         data)
+                                          self.export.get('callback'),
+                                          data)
             fh.write(data)
             fh.close()