Add query functionality

Add a method that calls `gerrit query` and returns the results as
a list of Change objects.

Change-Id: Ie58a61e569d457c56109e34041e9db95147de91c

2 files changed, 49 insertions, 0 deletions

diff --git a/pygerrit/__init__.py b/pygerrit/__init__.py
index d9574b6..93e6412 100644
--- a/pygerrit/__init__.py
+++ b/pygerrit/__init__.py
@@ -35,3 +35,18 @@ def from_json(json_data, key):
     if key in json_data:
         return json_data[key]
     return None
+
+
+def escape_string(string):
+    """ Escape a string for use in Gerrit commands.
+
+    Adds necessary escapes and surrounding double quotes to a
+    string so that it can be passed to any of the Gerrit commands
+    that require double-quoted strings.
+
+    """
+
+    result = string
+    result = result.replace('\\', '\\\\')
+    result = result.replace('"', '\\"')
+    return '"' + result + '"'
diff --git a/pygerrit/client.py b/pygerrit/client.py
index b501b92..5b1a24d 100644
--- a/pygerrit/client.py
+++ b/pygerrit/client.py
@@ -24,10 +24,13 @@ THE SOFTWARE.
 
 """
 
+from json import JSONDecoder
 from Queue import Queue, Empty, Full
 
+from pygerrit import escape_string
 from pygerrit.error import GerritError
 from pygerrit.events import GerritEventFactory
+from pygerrit.models import Change
 from pygerrit.ssh import GerritSSHClient
 from pygerrit.stream import GerritStream
 
@@ -42,6 +45,37 @@ class GerritClient(object):
         self._stream = None
         self._ssh_client = GerritSSHClient(host)
 
+    def query(self, term):
+        """ Run `gerrit query` with the given term.
+
+        Return a list of results as `Change` objects.
+
+        """
+        results = []
+        command = ["query", "--current-patch-set", "--all-approvals",
+                   "--format JSON", "--commit-message"]
+        if isinstance(term, list):
+            command += [escape_string(" ".join(term))]
+        else:
+            command += [escape_string(term)]
+        _stdin, stdout, _stderr = self._ssh_client.run_gerrit_command(command)
+        decoder = JSONDecoder()
+        for line in stdout.read().splitlines():
+            # Gerrit's response to the query command contains one or more
+            # lines of JSON-encoded strings.  The last one is a status
+            # dictionary containing the key "type" whose value indicates
+            # whether or not the operation was successful.
+            # According to http://goo.gl/h13HD it should be safe to use the
+            # presence of the "type" key to determine whether the dictionary
+            # represents a change or if it's the query status indicator.
+            data = decoder.decode(line)
+            if "type" in data:
+                if data["type"] == "error":
+                    raise GerritError("Query error: %s" % data["message"])
+            else:
+                results.append(Change(data))
+        return results
+
     def start_event_stream(self):
         """ Start streaming events from `gerrit stream-events`. """
         if not self._stream: