Refactor to set up columns in a const way by calling execute() early, before fetch()

2 files changed, 9 insertions, 11 deletions

diff --git a/project2/sql/sqlRows.cpp b/project2/sql/sqlRows.cpp
index f723269..6570a60 100644
--- a/project2/sql/sqlRows.cpp
+++ b/project2/sql/sqlRows.cpp
@@ -34,16 +34,16 @@ SqlRows::loadComplete(const CommonObjects * co)
 SqlRows::SqlState::SqlState(SelectPtr s) :
 	query(s)
 {
+	query->execute();
+	fields.resize(query->columnCount());
+	for (unsigned int c = 0; c < query->columnCount(); c++) {
+		columns.insert(new Column(c, (*query)[c].name));
+	}
 }
 
 const Columns &
 SqlRows::SqlState::getColumns() const
 {
-	if (columns.empty()) {
-		for (unsigned int c = 0; c < query->columnCount(); c++) {
-			columns.insert(new Column(c, (*query)[c].name));
-		}
-	}
 	return columns;
 }
 
@@ -51,13 +51,11 @@ void
 SqlRows::execute(const Glib::ustring & filter, const RowProcessorCallback & rp, ExecContext * ec) const
 {
 	unsigned int offset = 0;
-	SqlState ss(SelectPtr(db->getReadonly().newSelectCommand(sqlCommand.getSqlFor(filter))));
-	sqlCommand.bindParams(ec, ss.query.get(), offset);
+	auto select = SelectPtr(db->getReadonly().newSelectCommand(sqlCommand.getSqlFor(filter)));
+	sqlCommand.bindParams(ec, select.get(), offset);
+	SqlState ss(select);
 	while (ss.query->fetch()) {
 		HandleAsVariableType h;
-		if (ss.fields.empty()) {
-			ss.fields.resize(ss.query->columnCount());
-		}
 		for (unsigned int c = 0; c < ss.query->columnCount(); c++) {
 			const DB::Column & col = (*ss.query)[c];
 			col.apply(h);
diff --git a/project2/sql/sqlRows.h b/project2/sql/sqlRows.h
index 6f78dcd..46f3972 100644
--- a/project2/sql/sqlRows.h
+++ b/project2/sql/sqlRows.h
@@ -29,7 +29,7 @@ class SqlRows : public RowSet {
 				SqlState(SelectPtr query);
 				const Columns & getColumns() const;
 				SelectPtr query;
-				mutable Columns columns;
+				Columns columns;
 				friend class SqlRows;
 		};
 		const RdbmsDataSource * db;