/// <summary>
/// Executes the projection.
/// </summary>
/// <param name="projection">The projection.</param>
/// <param name="okayToDefer">if set to <c>true</c> [okay to defer].</param>
/// <param name="command">The command.</param>
/// <param name="values">The values.</param>
/// <returns></returns>
private Expression ExecuteProjection(ProjectionExpression projection, bool okayToDefer, QueryCommand command, Expression[] values)
{
okayToDefer &= (this.receivingMember != null && this.policy.IsDeferLoaded(this.receivingMember));
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);
string methExecute = okayToDefer ? "ExecuteDeferred" : "Execute";
// call low-level execute directly on supplied DbQueryProvider
Expression result = Expression.Call(this.executor, methExecute, new Type[] { projector.Body.Type }, Expression.Constant(command), projector, Expression.Constant(entity, typeof(MappingEntity)), Expression.NewArrayInit(typeof(object), values));
if (projection.Aggregator != null)
{
// apply aggregator
result = DbExpressionReplacer.Replace(projection.Aggregator.Body, projection.Aggregator.Parameters[0], result);
}
return(result);
}
/// <summary>
/// Builds the execute batch.
/// </summary>
/// <param name="batch">The batch.</param>
/// <returns></returns>
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)));
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);
}