public DbDataReader ExecuteDataReader(ActionContext context)
{
FieldDescription[] returningFields = DbCommandActionHelper.GetReturningFields(this.commandTree.Returning);
IList<IDictionary<string, object>> returningEntities = new List<IDictionary<string, object>>();
ITable table = null;
Expression expr = DbCommandActionHelper.GetEnumeratorExpression(this.commandTree.Predicate, this.commandTree, context.DbContainer, out table);
IQueryable entitiesToUpdate = DatabaseReflectionHelper.CreateTableQuery(expr, context.DbContainer.Internal);
Type type = TypeHelper.GetElementType(table.GetType());
// Collect the SetClause DbExpressions into a dictionary
IDictionary<string, DbExpression> setClauses = DbCommandActionHelper.GetSetClauseExpressions(this.commandTree.SetClauses);
// Collection for collection member bindings
IList<MemberBinding> memberBindings = new List<MemberBinding>();
TransformVisitor transform = new TransformVisitor(context.DbContainer.TypeConverter);
// Setup context for the predicate
ParameterExpression param = Expression.Parameter(type, "context");
using (transform.CreateVariable(param, this.commandTree.Target.VariableName))
{
// Initialize member bindings
foreach (PropertyInfo property in type.GetProperties())
{
Expression setter = null;
// Check if member has set clause
if (setClauses.ContainsKey(property.Name))
{
setter = transform.Visit(setClauses[property.Name]);
}
// If setter was found, insert it
if (setter != null)
{
// Type correction
setter = ExpressionHelper.CorrectType(setter, property.PropertyType);
memberBindings.Add(Expression.Bind(property, setter));
}
}
}
Expression updater =
Expression.Lambda(
Expression.MemberInit(Expression.New(type), memberBindings),
param);
IEnumerable<object> updatedEntities = DatabaseReflectionHelper.UpdateEntities(entitiesToUpdate, updater, context.Transaction);
int affectedRecords = 0;
foreach (object entity in updatedEntities)
{
affectedRecords++;
Dictionary<string, object> returningEntity =
DbCommandActionHelper.CreateReturningEntity(context, returningFields, entity);
returningEntities.Add(returningEntity);
}
return new EffortDataReader(
returningEntities,
affectedRecords,
returningFields,
context.DbContainer);
}
public static Expression GetEnumeratorExpression(
DbExpression predicate,
DbModificationCommandTree commandTree,
DbContainer container,
out ITable table)
{
TransformVisitor visitor = new TransformVisitor(container.TypeConverter);
visitor.TableProvider = container;
// Get the source expression
ConstantExpression source =
visitor.Visit(commandTree.Target.Expression) as ConstantExpression;
// This should be a constant expression
if (source == null)
{
throw new InvalidOperationException();
}
table = source.Value as ITable;
// Get the the type of the elements of the table
Type elementType = TypeHelper.GetElementType(source.Type);
// Create context
ParameterExpression context = Expression.Parameter(elementType, "context");
using (visitor.CreateVariable(context, commandTree.Target.VariableName))
{
// Create the predicate expression
LambdaExpression predicateExpression =
Expression.Lambda(
visitor.Visit(predicate),
context);
// Create Where expression
LinqMethodExpressionBuilder queryMethodBuilder =
new LinqMethodExpressionBuilder();
return queryMethodBuilder.Where(source, predicateExpression);
}
}