sql: return BatchResult from Statement.executeBatch()

src/sql/doc.md

@@ -203,5 +203,5 @@ For postgres, setup the fantest database and user account via:
 In addition, both JDBC drivers must be installed, and "etc/sql/config.props"
 must have a reference to the classpath of both drivers, e.g.
 
-    java.drivers=java.drivers=com.mysql.cj.jdbc.Driver,org.postgresql.Driver
+    java.drivers=com.mysql.cj.jdbc.Driver,org.postgresql.Driver
 

src/sql/fan/BatchExecutor.fan

@@ -28,21 +28,25 @@ class BatchExecutor
     queued.add(params)
     if (queued.size > maxChunkSize)
     {
-      results.addAll(stmt.executeBatch(queued))
+      r := stmt.executeBatch(queued)
+      result.updateCounts.addAll(r.updateCounts)
+      result.keys.addAll(r.keys)
       queued.clear
     }
   }
 
-  ** Finish execution, and return the concatenated results from each
-  ** call to Statement.executeBatch().
-  Int?[] finish()
+  ** Finish execution, and return the collated results from each call
+  ** to Statement.executeBatch().
+  BatchResult finish()
   {
     if (queued.size > 0)
     {
-      results.addAll(stmt.executeBatch(queued))
+      r := stmt.executeBatch(queued)
+      result.updateCounts.addAll(r.updateCounts)
+      result.keys.addAll(r.keys)
       queued.clear
     }
-    return results
+    return result
   }
 
 //////////////////////////////////////////////////////////////////////////
@@ -53,6 +57,6 @@ class BatchExecutor
   private Int maxChunkSize
 
   private [Str:Obj][] queued := [Str:Obj][,]
-  private Int?[] results := [,]
+  private BatchResult result := BatchResult(Int?[,], Obj?[,])
 }
 

src/sql/fan/Statement.fan

@@ -66,22 +66,31 @@ class Statement
 
   **
   ** Execute a batch of commands on a prepared Statement. If all commands
-  ** execute successfully, returns an array of update counts.
+  ** execute successfully, return a BatchResult containing an array of update
+  ** counts, and an array of auto-generated keys.
   **
-  ** For each element in the array, if the element is non-null, then it
-  ** represents an update count giving the number of rows in the database that
-  ** were affected by the command's execution.
+  ** For each element in the update counts array, if the element is non-null,
+  ** then it represents an update count giving the number of rows in the
+  ** database that were affected by the command's execution. If a given array
+  ** element is null, it indicates that the command was processed successfully
+  ** but that the number of rows affected is unknown.
   **
-  ** If a given array element is null, it indicates that the command was
-  ** processed successfully but that the number of rows affected is unknown.
+  ** The keys array contains the auto-generated keys, if any, for each command.
+  ** An element is null if the driver did not return a key for that command.
+  ** Note that some drivers return the keys even if they were not
+  ** auto-generated.
+  **
+  ** If the driver returns auto-generated keys for some but not all of the
+  ** commands, throw SqlErr since the keys cannot be correlated to their
+  ** commands.
   **
   ** If one of the commands in a batch update fails to execute properly, this
   ** method throws a SqlErr that wraps a java.sql.BatchUpdateException, and a
   ** JDBC driver may or may not continue to process the remaining commands in
   ** the batch, consistent with the underlying DBMS -- either always continuing
   ** to process commands or never continuing to process commands.
   **
-  native Int?[] executeBatch([Str:Obj]?[] paramsList)
+  native BatchResult executeBatch([Str:Obj]?[] paramsList)
 
   **
   ** If the last execute has more results from a multi-result stored
@@ -118,3 +127,23 @@ class Statement
 
 }
 
+**************************************************************************
+** BatchResult
+**************************************************************************
+
+** BatchResult contains the result of a call to Statement.executeBatch().
+class BatchResult
+{
+  new make(Int?[] updateCounts, Obj?[] keys)
+  {
+    this.updateCounts = updateCounts
+    this.keys = keys
+  }
+
+  ** The number of rows that were affected by each command's execution.
+  Int?[] updateCounts
+
+  ** The keys that were auto-generated by each command.
+  Obj?[] keys
+}
+

src/sql/java/StatementPeer.java

@@ -305,10 +305,7 @@ private Object executeResult(Statement self, boolean isResultSet)
         List keys = null;
         while (rs.next())
         {
-          // get key as Long or String
-          Object key;
-          try { key = rs.getLong(1); }
-          catch (Exception e) { key = rs.getString(1); }
+          Object key = readGenKey(rs);
 
           // lazily create keys list with proper type
           if (keys == null)
@@ -330,12 +327,60 @@ private Object executeResult(Statement self, boolean isResultSet)
     return Long.valueOf(-1);
   }
 
-  public List executeBatch(Statement self, List paramsList)
+  /**
+   * Read the auto-generated key for the current row as a Long, or as a
+   * String for databases like Oracle which do not allow access as an Int.
+   */
+  private static Object readGenKey(ResultSet rs)
+    throws SQLException
+  {
+    try { return rs.getLong(1); }
+    catch (Exception e) { return rs.getString(1); }
+  }
+
+  /**
+   * Auto-generated keys for the batch just executed, with one entry per
+   * command.  Entries are null if the driver returned no keys at all.  If
+   * the driver returns keys for some but not all of the commands they cannot
+   * be correlated to their commands, so that case is an error.
+   */
+  private List readBatchGenKeys(PreparedStatement pstmt, int numCommands)
+    throws SQLException
+  {
+    List keys = List.make(Sys.ObjType.toNullable(), numCommands);
+
+    if (isAutoKeys)
+    {
+      ResultSet rs = pstmt.getGeneratedKeys();
+      try
+      {
+        while (rs.next()) keys.add(readGenKey(rs));
+      }
+      finally
+      {
+        rs.close();
+      }
+
+      if (keys.size() == numCommands) return keys;
+
+      if (keys.size() != 0)
+        throw SqlErr.make("Driver returned " + keys.size() +
+          " auto-generated keys for " + numCommands + " batch commands");
+    }
+
+    // no keys returned: one null per command
+    for (int i = 0; i < numCommands; i++) keys.add(null);
+    return keys;
+  }
+
+  public BatchResult executeBatch(Statement self, List paramsList)
   {
     if (!prepared)
       throw SqlErr.make("Statement has not been prepared.");
     PreparedStatement pstmt = (PreparedStatement)stmt;
 
+    List genKeys = List.make(Sys.ObjType.toNullable(), 0);
+
     try
     {
       // add batch
@@ -348,8 +393,11 @@ public List executeBatch(Statement self, List paramsList)
       // execute batch
       int[] exec = pstmt.executeBatch();
 
+      // gather auto-generated keys before the statement is reused
+      genKeys = readBatchGenKeys(pstmt, (int)paramsList.size());
+
       // process result
-      List result = List.make(Sys.IntType, exec.length);
+      List updateCounts = List.make(Sys.IntType, exec.length);
       for (int i = 0; i < exec.length; i++)
       {
         int n = exec[i];
@@ -358,9 +406,10 @@ public List executeBatch(Statement self, List paramsList)
         // java.sql.Statement.SUCCESS_NO_INFO. We treat that as a null,
         // indicating that the command was processed successfully but that the
         // number of rows affected is unknown.
-        result.add(n < 0 ? null : (long)n);
+        updateCounts.add(n < 0 ? null : (long)n);
       }
-      return result;
+
+      return BatchResult.make(updateCounts, genKeys);
     }
     catch (SQLException ex)
     {