[chronojump] Simplifies code when error checking and avoids a possible crash.

[Carles Pina i Estany <carlespina src gnome org>]

commit 7959883dc32ba290134e316327eb244d097952f5
Author: Carles Pina i Estany <carles pina cat>
Date:   Wed Oct 26 00:04:03 2016 +0200

    Simplifies code when error checking and avoids a possible crash.
    
    (the crash would have happened if the chronojump_importer.py didn't
    return the databaseVersion)

 src/chronojumpImporter.cs |   11 +++++++----
 src/json.cs               |   15 +++++++++++++++
 2 files changed, 22 insertions(+), 4 deletions(-)
---
diff --git a/src/chronojumpImporter.cs b/src/chronojumpImporter.cs
index 8bd4683..7cad699 100644
--- a/src/chronojumpImporter.cs
+++ b/src/chronojumpImporter.cs
@@ -234,11 +234,14 @@ class ChronojumpImporter
                } else {
                        JsonValue json = JsonValue.Parse (information.output);
 
+                       if (!json.ContainsKey ("sessions")) {
+                               LogB.Information ("Trying to import a session but sessions doesn't exist. 
Output:" + information.output);
+                               return "UNKNOWN";
+                       }
+
                        foreach(JsonValue session in json["sessions"])
                        {
-                               if (session ["uniqueID"] == sessionId) {
-                                       return session ["name"];
-                               }
+                               return JsonUtils.valueOrDefault (session, "name", "UNKNOWN");
                        }
                        LogB.Information ("Trying to import a session that we can't find the name. Output:" + 
information.output);
                        return "UNKNOWN";
@@ -251,7 +254,7 @@ class ChronojumpImporter
 
                if (information.success) {
                        JsonValue json = JsonValue.Parse (information.output);
-                       return new Result (true, json ["databaseVersion"]);
+                       return new Result (true, JsonUtils.valueOrDefault(json, "databaseVersion", "0"));
                } else {
                        return information;
                }
diff --git a/src/json.cs b/src/json.cs
index bb930ce..4814f26 100644
--- a/src/json.cs
+++ b/src/json.cs
@@ -244,3 +244,18 @@ public class Json
 
        ~Json() {}
 }
+
+class JsonUtils
+{
+       public static JsonValue valueOrDefault(JsonValue jsonObject, string key, string defaultValue)
+       {
+               // Returns jsonObject[key] if it exists. If the key doesn't exist returns defaultValue and
+               // logs the anomaly into the Chronojump log.
+               if (jsonObject.ContainsKey (key)) {
+                       return jsonObject ["key"];
+               } else {
+                       LogB.Information ("JsonUtils::valueOrDefault: returning default (" + defaultValue + 
") from JSON: " + jsonObject.ToString ());
+                       return defaultValue;
+               }
+       }
+}
\ No newline at end of file