Accept empty string for the limit in a reconciliation config

main/src/com/google/refine/model/recon/StandardReconConfig.java

@@ -111,8 +111,13 @@ public class StandardReconConfig extends ReconConfig {
         }
         
         JSONObject t = obj.has("type") && !obj.isNull("type") ? obj.getJSONObject("type") : null;
-        
+
-        int limit = obj.has("limit") && !obj.isNull("limit") ? obj.getInt("limit") : 0;
+        int limit;
+        try {
+            limit = obj.has("limit") && !obj.isNull("limit") ? obj.getInt("limit") : 0;
+        } catch(JSONException e) {
+            limit = 0;
+        }
         
         return new StandardReconConfig(
             obj.getString("service"),

main/tests/server/src/com/google/refine/tests/model/ReconTests.java

@@ -53,7 +53,7 @@ public class ReconTests extends RefineTest {
      * @throws Exception
      */
     @Test
-    public void limitJSONKeyTest() throws Exception {
+    public void limitJSONKeyAsIntTest() throws Exception {
         JSONObject obj = new JSONObject(
                 " {\n" + 
                 "        \"mode\": \"standard-service\",\n" + 
@@ -74,4 +74,35 @@ public class ReconTests extends RefineTest {
         // Assert the object is created
         Assert.assertTrue(config != null);
     }
+    
+    /**
+     * Regression for issue #1526:
+     * the UI used to send an empty limit as an empty string, which
+     * failed to be parsed by the backend.
+     * @throws Exception
+     */
+    @Test
+    public void limitJSONKeyAsEmptyStringTest() throws Exception {
+        JSONObject obj = new JSONObject(
+                " {\n" + 
+                "        \"mode\": \"standard-service\",\n" + 
+                "        \"service\": \"https://tools.wmflabs.org/openrefine-wikidata/en/api\",\n" + 
+                "        \"identifierSpace\": \"http://www.wikidata.org/entity/\",\n" + 
+                "        \"schemaSpace\": \"http://www.wikidata.org/prop/direct/\",\n" + 
+                "        \"type\": {\n" + 
+                "                \"id\": \"Q13442814\",\n" + 
+                "                \"name\": \"scientific article\"\n" + 
+                "        },\n" + 
+                "        \"autoMatch\": true,\n" + 
+                "        \"columnDetails\": [],\n" + 
+                "        \"limit\": \"\"\n" + 
+                " }");
+        
+        ReconConfig config = StandardReconConfig.reconstruct(obj);
+        
+        // Assert the object is created
+        Assert.assertTrue(config != null);
+    }
+    
+
 }