public Expression GetFilterExpression(ParameterExpression itemPram, FilterComparisonOperator comparisonOperator, string valueString)
{
var getterMemberExpr = _reader.GetSelectExpression(itemPram);
if (getterMemberExpr == null)
{
throw new InvalidCastException("Getter expression returned from IFieldReader is not of type MemberExpression.");
}
object valueObj = ConversionUtility.ConvertString(valueString, _reader.FieldType);
ConstantExpression variableExpression = Expression.Constant(valueObj, _reader.FieldType); // TODO variable not constant?
var operatorMethod = GetOperatorExpressionMethod(comparisonOperator);
Expression predicateExpression = operatorMethod.Invoke(getterMemberExpr, variableExpression);
return(predicateExpression);
}
public MemberInitExpression Build <TItem>(ParameterExpression itemPram, IFieldProvider <TItem> fieldProvider)
where TItem : class
{
return(Build(delegate(FieldInfo fi)
{
IFieldReader <TItem> reader = fieldProvider.GetReader(fi.Name);
Debug.Assert(reader != null, "Reader should definitely not be null here.");
return Expression.Bind(fi, reader.GetSelectExpression(itemPram));
}));
}
public MemberInitExpression Build <TItem>(ParameterExpression itemPram, IDictionary <string, IFieldReader <TItem> > fieldReaders)
where TItem : class
{
return(Build(delegate(FieldInfo fi)
{
Debug.Assert(fieldReaders.ContainsKey(fi.Name));
IFieldReader <TItem> reader = fieldReaders[fi.Name];
return Expression.Bind(fi, reader.GetSelectExpression(itemPram));
}));
}
/// <summary>
/// Loads a single scalar field reader from a single <see cref="itemQuery"/>.
/// </summary>
public static async Task <object> LoadScalarValueAsync <TItem>([NotNull] IFieldReader <TItem> reader, IQueryableSingle <TItem> itemQuery, ForEachAsyncDelegate <object> forEachAsync)
{
if (reader == null)
{
throw new ArgumentNullException(nameof(reader));
}
ParameterExpression itemPram = Expression.Parameter(typeof(TItem), "itm");
Expression selectExpression = reader.GetSelectExpression(itemPram);
IQueryable selectScalarOnlyQuery = ExpressionTreeHelpers.GetSelectExpressionQuery(itemQuery, itemPram, selectExpression);
object loadedValue = await ItemQueryHelper.SingleOrCreateAsync(selectScalarOnlyQuery, forEachAsync, () => throw new ParentItemNotFoundException());
if (reader.Replacer != null)
{
await reader.Replacer.LoadAsync(itemQuery);
return(reader.Replacer.GetReplacement(loadedValue));
}
return(loadedValue);
}
public Expression GetSelectExpression(ParameterExpression itemPram)
{
return(_fieldReaderImplementation.GetSelectExpression(itemPram));
}
