Implement blob re-initialization

include/private/soci-trivial-blob-backend.h

@@ -2,6 +2,7 @@
 #define SOCI_PRIVATE_SOCI_TRIVIAL_BLOB_BACKEND_H_INCLUDED
 
 #include "soci/soci-backend.h"
+#include "soci/session.h"
 
 #include <vector>
 #include <cstring>
@@ -22,6 +23,8 @@ namespace details
 class trivial_blob_backend : public details::blob_backend
 {
 public:
+    trivial_blob_backend(details::session_backend &backend) : session_(backend) {}
+
     std::size_t get_len() override { return buffer_.size(); }
 
     std::size_t read_from_start(void* buf, std::size_t toRead,
@@ -71,7 +74,10 @@ class trivial_blob_backend : public details::blob_backend
 
     const std::uint8_t *get_buffer() const { return buffer_.data(); }
 
+    details::session_backend &get_session_backend() override { return session_; }
+
 protected:
+    details::session_backend &session_;
     std::vector< std::uint8_t > buffer_;
 };
 

include/soci/blob.h

@@ -40,6 +40,7 @@ class SOCI_DECL blob
 
     // (Re)initializes this blob
     void initialize(session &s);
+    void initialize(details::blob_backend *backend);
 
     std::size_t get_len();
 

include/soci/db2/soci-db2.h

@@ -233,6 +233,7 @@ struct db2_blob_backend : details::blob_backend
     std::size_t write_from_start(const void* buf, std::size_t toWrite, std::size_t offset = 0) override;
     std::size_t append(const void* buf, std::size_t toWrite) override;
     void trim(std::size_t newLen) override;
+    details::session_backend &get_session_backend() override;
 
     db2_session_backend& session_;
 };

include/soci/empty/soci-empty.h

@@ -146,6 +146,8 @@ struct empty_blob_backend : details::blob_backend
     std::size_t append(const void* buf, std::size_t toWrite) override;
     void trim(std::size_t newLen) override;
 
+    details::session_backend &get_session_backend() override;
+
     empty_session_backend& session_;
 };
 

include/soci/firebird/soci-firebird.h

@@ -266,6 +266,8 @@ struct firebird_blob_backend : details::blob_backend
     std::size_t append(const void *buf, std::size_t toWrite) override;
     void trim(std::size_t newLen) override;
 
+    details::session_backend &get_session_backend() override;
+
     // Writes the current data into the database by allocating a new BLOB
     // object for it.
     //

include/soci/odbc/soci-odbc.h

@@ -306,6 +306,7 @@ struct odbc_blob_backend : details::blob_backend
     std::size_t write_from_start(const void *buf, std::size_t toWrite, std::size_t offset = 0) override;
     std::size_t append(const void *buf, std::size_t toWrite) override;
     void trim(std::size_t newLen) override;
+    details::session_backend &get_session_backend() override;
 
     odbc_session_backend &session_;
 };

include/soci/oracle/soci-oracle.h

@@ -285,6 +285,8 @@ struct oracle_blob_backend : details::blob_backend
 
     void ensure_initialized();
 
+    oracle_session_backend &get_session_backend() override;
+
 private:
     std::size_t do_deprecated_read(std::size_t offset, void *buf, std::size_t toRead) override
     {

include/soci/postgresql/soci-postgresql.h

@@ -370,6 +370,8 @@ class postgresql_blob_backend : public details::blob_backend
 
     void reset();
 
+    details::session_backend &get_session_backend() override;
+
 private:
     postgresql_session_backend & session_;
     blob_details details_;

include/soci/soci-backend.h

@@ -294,6 +294,8 @@ class rowid_backend
     virtual ~rowid_backend() {}
 };
 
+class session_backend;
+
 // polymorphic blob backend
 
 class blob_backend
@@ -312,6 +314,8 @@ class blob_backend
 
     virtual void trim(std::size_t newLen) = 0;
 
+    virtual session_backend &get_session_backend() = 0;
+
     // Deprecated functions with backend-specific semantics preserved only for
     // compatibility.
     [[deprecated("Use read_from_start instead")]]

src/backends/db2/blob.cpp

@@ -53,6 +53,11 @@ void db2_blob_backend::trim(std::size_t /* newLen */)
     throw soci_error("BLOBs are not supported.");
 }
 
+details::session_backend &db2_blob_backend::get_session_backend()
+{
+    return session_;
+}
+
 #ifdef _MSC_VER
 # pragma warning(pop)
 #endif

src/backends/empty/blob.cpp

@@ -53,6 +53,11 @@ void empty_blob_backend::trim(std::size_t /* newLen */)
     throw soci_error("BLOBs are not supported.");
 }
 
+details::session_backend &empty_blob_backend::get_session_backend()
+{
+    return session_;
+}
+
 #ifdef _MSC_VER
 # pragma warning(pop)
 #endif

src/backends/firebird/blob.cpp

@@ -325,3 +325,8 @@ long firebird_blob_backend::getBLOBInfo()
 
     return total_length;
 }
+
+details::session_backend &firebird_blob_backend::get_session_backend()
+{
+    return session_;
+}

src/backends/mysql/blob.cpp

@@ -20,8 +20,8 @@
 using namespace soci;
 using namespace soci::details;
 
-mysql_blob_backend::mysql_blob_backend(mysql_session_backend &)
-    : details::trivial_blob_backend()
+mysql_blob_backend::mysql_blob_backend(mysql_session_backend &backend)
+    : details::trivial_blob_backend(backend)
 {
 }
 

src/backends/odbc/blob.cpp

@@ -53,6 +53,11 @@ void odbc_blob_backend::trim(std::size_t /* newLen */)
     throw soci_error("BLOBs are not supported.");
 }
 
+details::session_backend &odbc_blob_backend::get_session_backend()
+{
+    return session_;
+}
+
 #ifdef _MSC_VER
 # pragma warning(pop)
 #endif

src/backends/oracle/blob.cpp

@@ -239,3 +239,8 @@ void oracle_blob_backend::ensure_initialized()
         initialized_ = true;
     }
 }
+
+details::session_backend &oracle_blob_backend::get_session_backend()
+{
+    return session_;
+}

src/backends/postgresql/blob.cpp

@@ -320,3 +320,8 @@ void postgresql_blob_backend::clone()
         lo_close(session_.conn_, old_details.fd);
     }
 }
+
+details::session_backend &postgresql_blob_backend::get_session_backend()
+{
+    return session_;
+}

src/backends/sqlite3/blob.cpp

@@ -13,8 +13,8 @@
 
 using namespace soci;
 
-sqlite3_blob_backend::sqlite3_blob_backend(sqlite3_session_backend &)
-    : details::trivial_blob_backend()
+sqlite3_blob_backend::sqlite3_blob_backend(sqlite3_session_backend &backend)
+    : details::trivial_blob_backend(backend)
 {
 }
 

src/core/blob.cpp

@@ -28,7 +28,12 @@ bool blob::is_valid() const
 
 void blob::initialize(session &session)
 {
-    backEnd_.reset(session.make_blob_backend());
+    initialize(session.make_blob_backend());
+}
+
+void blob::initialize(details::blob_backend *backend)
+{
+    backEnd_.reset(backend);
 }
 
 std::size_t blob::get_len()

src/core/row.cpp

@@ -121,7 +121,7 @@ blob row::move_as<blob>(std::size_t pos) const
     type_conversion<blob>::move_from_base(baseVal, *indicators_.at(pos), ret);
 
     // Re-initialize blob object so it can be used in further queries
-    baseVal.initialize(session);
+    baseVal.initialize(ret.get_backend()->get_session_backend().make_blob_backend());
 
     return ret;
 }