protected virtual Expression BuildExecuteBatch(BatchExpression batch)
{
// parameterize query
Expression operation = this.Parameterize(batch.Operation.Body);
string commandText = this.linguist.Format(operation);
var namedValues = NamedValueGatherer.Gather(operation);
QueryCommand command = new QueryCommand(commandText, namedValues.Select(v => new QueryParameter(v.Name, v.Type, v.QueryType)));
Expression[] values = namedValues.Select(v => Expression.Convert(this.Visit(v.Value), typeof(object))).ToArray();
Expression paramSets = Expression.Call(typeof(Enumerable), "Select", new Type[] { batch.Operation.Parameters[1].Type, typeof(object[]) },
batch.Input,
Expression.Lambda(Expression.NewArrayInit(typeof(object), values), new[] { batch.Operation.Parameters[1] })
);
Expression plan = null;
ProjectionExpression projection = ProjectionFinder.FindProjection(operation);
if (projection != null)
{
var saveScope = this.scope;
ParameterExpression reader = Expression.Parameter(typeof(FieldReader), "r" + nReaders++);
this.scope = new Scope(this.scope, reader, projection.Select.Alias, projection.Select.Columns);
LambdaExpression projector = Expression.Lambda(this.Visit(projection.Projector), reader);
this.scope = saveScope;
var entity = EntityFinder.Find(projection.Projector);
command = new QueryCommand(command.CommandText, command.Parameters);
plan = Expression.Call(this.executor, "ExecuteBatch", new Type[] { projector.Body.Type },
Expression.Constant(command),
paramSets,
projector,
Expression.Constant(entity, typeof(MappingEntity)),
batch.BatchSize,
batch.Stream
);
}
else
{
plan = Expression.Call(this.executor, "ExecuteBatch", null,
Expression.Constant(command),
paramSets,
batch.BatchSize,
batch.Stream
);
}
return(plan);
}
protected override Expression VisitBatch(BatchExpression batch)
{
if (this.linguist.Language.AllowsMultipleCommands || !IsMultipleCommands(batch.Operation.Body as CommandExpression))
{
return(this.BuildExecuteBatch(batch));
}
else
{
var source = this.Visit(batch.Input);
var op = this.Visit(batch.Operation.Body);
var fn = Expression.Lambda(op, batch.Operation.Parameters[1]);
return(Expression.Call(this.GetType(), "Batch", new Type[] { TypeHelper.GetElementType(source.Type), batch.Operation.Body.Type }, source, fn, batch.Stream));
}
}
