src/main/java/org/embulk/output/SalesforceOutputPlugin.java in embulk-output-salesforce-0.1.0 vs src/main/java/org/embulk/output/SalesforceOutputPlugin.java in embulk-output-salesforce-0.1.1

@@ -8,10 +8,11 @@
 import com.sforce.soap.partner.SaveResult;
 import com.sforce.soap.partner.UpsertResult;
 import com.sforce.soap.partner.sobject.SObject;
 import com.sforce.ws.ConnectionException;
 import com.sforce.ws.ConnectorConfig;
+import java.io.File;
 import java.io.FileWriter;
 import java.io.IOException;
 import java.text.SimpleDateFormat;
 import java.util.ArrayList;
 import java.util.Calendar;
@@ -53,11 +54,11 @@
 
         @Config("password")
         public String getPassword();
 
         @Config("login_endpoint")
-        @ConfigDefault("https://login.salesforce.com")
+        @ConfigDefault("\"https://login.salesforce.com\"")
         public Optional<String> getLoginEndpoint();
         
         @Config("sobject")
         public String getSObject();
         
@@ -76,21 +77,30 @@
         @Config("version")
         @ConfigDefault("34.0")
         public Optional<String> getVersion();
         
         @Config("result_dir")
-        @ConfigDefault("\"./target\"")
+        @ConfigDefault("null")
         public Optional<String> getResultDir();
     }
 
     @Override
     public ConfigDiff transaction(ConfigSource config,
             Schema schema, int taskCount,
             OutputPlugin.Control control)
     {
         PluginTask task = config.loadConfig(PluginTask.class);
         logger = Exec.getLogger(getClass());
+        
+        if (task.getResultDir().isPresent() && task.getResultDir().get() != null) {
+            File resultDir = new File(task.getResultDir().get());
+            if (!resultDir.exists() || !resultDir.isDirectory()) {
+                logger.error("{} is not exist or is not directory.", task.getResultDir().get());
+                throw new RuntimeException(task.getResultDir().get() + " is not exist or is not directory.");
+            }
+        }
+        
         final String username = task.getUsername();
         final String password = task.getPassword();
         final String loginEndpoint = task.getLoginEndpoint().get();
         try {
             if (client == null) {
@@ -143,11 +153,11 @@
     }
 
     public class SalesforcePageOutput
             implements TransactionalPageOutput
     {
-        private final String datePostFix = new SimpleDateFormat("yyyyMMddhhmmssSSS").format(new Date());
+        private final String dateSuffix = new SimpleDateFormat("yyyyMMddhhmmssSSS").format(new Date());
     
         private final PageReader pageReader;
         private final PartnerConnection client;
         private final int batchSize;
         private List<SObject> records;
@@ -346,19 +356,25 @@
 
         private void createResultsFiles(List<SObject> records, ResultWrapper resultWrapper) throws IOException{
             ICsvListWriter successListWriter = null;
             ICsvListWriter errorListWriter = null;
             try {
-                String successFileName = this.resultDir + "/success_" + datePostFix + ".csv";
+                String successFileName = this.resultDir + "/success_" + dateSuffix + ".csv";
+                Boolean isExistSuccessFile = new File(successFileName).exists();
                 successListWriter = new CsvListWriter(new FileWriter(successFileName, true), 
                         CsvPreference.STANDARD_PREFERENCE);
-                //successListWriter.write(createSuccessHeader());
+                if (!isExistSuccessFile) {
+                    successListWriter.write(createSuccessHeader());
+                }
                 
-                String errorFileName = this.resultDir + "/error_" + datePostFix + ".csv";
+                String errorFileName = this.resultDir + "/error_" + dateSuffix + ".csv";
+                Boolean isExistErrorFile = new File(errorFileName).exists();
                 errorListWriter = new CsvListWriter(new FileWriter(errorFileName, true), 
                         CsvPreference.STANDARD_PREFERENCE);
-                //errorListWriter.write(createErrorHeader());
-
+                if (!isExistErrorFile) {
+                    errorListWriter.write(createErrorHeader());
+                }
+                    
                 CellProcessor[] processors = new CellProcessor[pageReader.getSchema().getColumns().size() + 1];
                 ArrayList<ArrayList<String>> errorValues = new ArrayList<>();
                 for (Integer i = 0, imax = records.size(); i < imax; i++) {
                     SObject record = records.get(i);