Detect and throw when object/view with long data is re-loaded from query result

7 files changed, 46 insertions, 7 deletions

diff --git a/odb/mssql/exceptions.cxx b/odb/mssql/exceptions.cxx
index 1b415a7..f14fc59 100644
--- a/odb/mssql/exceptions.cxx
+++ b/odb/mssql/exceptions.cxx
@@ -78,5 +78,16 @@ namespace odb
     {
       return what_.c_str ();
     }
+
+    //
+    // long_data_reload
+    //
+
+    const char* long_data_reload::
+    what () const throw ()
+    {
+      return "attempt to re-load object or view with long data "
+        "from query result";
+    }
   }
 }
diff --git a/odb/mssql/exceptions.hxx b/odb/mssql/exceptions.hxx
index 3e7a845..b31a83d 100644
--- a/odb/mssql/exceptions.hxx
+++ b/odb/mssql/exceptions.hxx
@@ -108,6 +108,12 @@ namespace odb
     private:
       std::string what_;
     };
+
+    struct LIBODB_MSSQL_EXPORT long_data_reload: odb::exception
+    {
+      virtual const char*
+      what () const throw ();
+    };
   }
 }
 
diff --git a/odb/mssql/object-result.hxx b/odb/mssql/object-result.hxx
index 9eaa4f5..6380993 100644
--- a/odb/mssql/object-result.hxx
+++ b/odb/mssql/object-result.hxx
@@ -67,6 +67,7 @@ namespace odb
     private:
       details::shared_ptr<select_statement> statement_;
       object_statements<object_type>& statements_;
+      bool can_load_;
       bool use_copy_;
       typename object_traits::image_type* image_copy_;
     };
@@ -113,6 +114,7 @@ namespace odb
     private:
       details::shared_ptr<select_statement> statement_;
       object_statements_no_id<object_type>& statements_;
+      bool can_load_;
       bool use_copy_;
       typename object_traits::image_type* image_copy_;
     };
diff --git a/odb/mssql/object-result.txx b/odb/mssql/object-result.txx
index 338f78a..161978e 100644
--- a/odb/mssql/object-result.txx
+++ b/odb/mssql/object-result.txx
@@ -6,8 +6,9 @@
 #include <cassert>
 
 #include <odb/callback.hxx>
-#include <odb/exceptions.hxx>
+#include <odb/exceptions.hxx> // result_not_cached
 
+#include <odb/mssql/exceptions.hxx> // long_data_reload
 #include <odb/mssql/object-statements.hxx>
 
 namespace odb
@@ -50,6 +51,9 @@ namespace odb
     void object_result_impl<T>::
     load (object_type& obj, bool)
     {
+      if (!can_load_)
+        throw long_data_reload ();
+
       // This is a top-level call so the statements cannot be locked.
       //
       assert (!statements_.locked ());
@@ -66,7 +70,7 @@ namespace odb
       // If we are using a copy, make sure the callback information for
       // long data also comes from the copy.
       //
-      statement_->stream_result (
+      can_load_ = !statement_->stream_result (
         use_copy_ ? &statements_.image () : 0,
         use_copy_ ? image_copy_ : 0);
 
@@ -103,6 +107,7 @@ namespace odb
     void object_result_impl<T>::
     next ()
     {
+      can_load_ = true;
       this->current (pointer_type ());
 
       typename object_traits::image_type& im (statements_.image ());
@@ -200,6 +205,9 @@ namespace odb
     void object_result_impl_no_id<T>::
     load (object_type& obj)
     {
+      if (!can_load_)
+        throw long_data_reload ();
+
       odb::database& db (this->database ());
 
       object_traits::callback (db, obj, callback_event::pre_load);
@@ -211,7 +219,7 @@ namespace odb
       // If we are using a copy, make sure the callback information for
       // long data also comes from the copy.
       //
-      statement_->stream_result (
+      can_load_ = !statement_->stream_result (
         use_copy_ ? &statements_.image () : 0,
         use_copy_ ? image_copy_ : 0);
 
@@ -222,6 +230,7 @@ namespace odb
     void object_result_impl_no_id<T>::
     next ()
     {
+      can_load_ = true;
       this->current (pointer_type ());
 
       typename object_traits::image_type& im (statements_.image ());
diff --git a/odb/mssql/statement.hxx b/odb/mssql/statement.hxx
index 3bea55f..6eacec6 100644
--- a/odb/mssql/statement.hxx
+++ b/odb/mssql/statement.hxx
@@ -122,15 +122,20 @@ namespace odb
       result
       fetch ();
 
-      void
+      // Return true if any long data was streamed.
+      //
+      bool
       stream_result (void* old_base = 0, void* new_base = 0)
       {
-        if (first_long_ != result_.count)
+        bool ld (first_long_ != result_.count);
+
+        if (ld)
           statement::stream_result (result_.bind,
                                     first_long_,
                                     result_.count,
                                     old_base,
                                     new_base);
+        return ld;
       }
 
       void
diff --git a/odb/mssql/view-result.hxx b/odb/mssql/view-result.hxx
index e4a523a..cf3dde1 100644
--- a/odb/mssql/view-result.hxx
+++ b/odb/mssql/view-result.hxx
@@ -63,6 +63,7 @@ namespace odb
     private:
       details::shared_ptr<select_statement> statement_;
       view_statements<view_type>& statements_;
+      bool can_load_;
       bool use_copy_;
       typename view_traits::image_type* image_copy_;
     };
diff --git a/odb/mssql/view-result.txx b/odb/mssql/view-result.txx
index 4b5053d..3d86206 100644
--- a/odb/mssql/view-result.txx
+++ b/odb/mssql/view-result.txx
@@ -4,8 +4,9 @@
 // license   : ODB NCUEL; see accompanying LICENSE file
 
 #include <odb/callback.hxx>
-#include <odb/exceptions.hxx>
+#include <odb/exceptions.hxx> // result_not_cached
 
+#include <odb/mssql/exceptions.hxx> // long_data_reload
 #include <odb/mssql/view-statements.hxx>
 
 namespace odb
@@ -44,6 +45,9 @@ namespace odb
     void view_result_impl<T>::
     load (view_type& view)
     {
+      if (!can_load_)
+        throw long_data_reload ();
+
       odb::database& db (this->database ());
 
       view_traits::callback (db, view, callback_event::pre_load);
@@ -55,7 +59,7 @@ namespace odb
       // If we are using a copy, make sure the callback information for
       // long data also comes from the copy.
       //
-      statement_->stream_result (
+      can_load_ = !statement_->stream_result (
         use_copy_ ? &statements_.image () : 0,
         use_copy_ ? image_copy_ : 0);
 
@@ -66,6 +70,7 @@ namespace odb
     void view_result_impl<T>::
     next ()
     {
+      can_load_ = true;
       this->current (pointer_type ());
 
       typename view_traits::image_type& im (statements_.image ());