1 files changed, 23 insertions, 1 deletions
diff --git a/model-integration/src/main/java/ai/vespa/rankingexpression/importer/xgboost/XGBoostImporter.java b/model-integration/src/main/java/ai/vespa/rankingexpression/importer/xgboost/XGBoostImporter.java
index ac462cc39eb..686cf6cd2df 100644
--- a/model-integration/src/main/java/ai/vespa/rankingexpression/importer/xgboost/XGBoostImporter.java
+++ b/model-integration/src/main/java/ai/vespa/rankingexpression/importer/xgboost/XGBoostImporter.java
@@ -1,11 +1,13 @@
 // Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package ai.vespa.rankingexpression.importer.xgboost;
 
+import com.yahoo.io.IOUtils;
 import com.yahoo.searchlib.rankingexpression.RankingExpression;
 import ai.vespa.rankingexpression.importer.ImportedModel;
 import ai.vespa.rankingexpression.importer.ModelImporter;
 import com.yahoo.searchlib.rankingexpression.parser.ParseException;
 
+import java.io.BufferedReader;
 import java.io.File;
 import java.io.IOException;
 
@@ -22,7 +24,27 @@ public class XGBoostImporter extends ModelImporter {
         File modelFile = new File(modelPath);
         if ( ! modelFile.isFile()) return false;
 
-        return modelFile.toString().endsWith(".json"); // No other models ends by json yet
+        return modelFile.toString().endsWith(".json") && probe(modelFile);
+    }
+
+    /**
+     * Returns true if the give file looks like an XGBoost json file.
+     * Currently, we just check if the file has an array on the top level.
+     */
+    private boolean probe(File modelFile) {
+        try {
+            BufferedReader reader = IOUtils.createReader(modelFile.getAbsolutePath());
+            String line;
+            while ((line = reader.readLine()) != null) {
+                line = line.trim();
+                if (line.startsWith("[")) return true;
+                if ( ! line.isEmpty()) return false;
+            }
+            return false;
+        }
+        catch (IOException e) {
+            throw new IllegalArgumentException("Could not read '" + modelFile + "'", e);
+        }
     }
 
     @Override