private static Expression CreateExpressionForCriteria(ParameterExpression parameter,
SearchCriteriaDomainModel searchCriteria)
{
var isCriteriaCollection = false;
var constants = new List <ConstantExpression>();
var allFieldParts = searchCriteria.FieldName.Split('.').ToList();
//MemberExpression member = null;
var member = Expression.Property(parameter, allFieldParts.First());
allFieldParts.Remove(allFieldParts.First());
Expression expression = null;
if (allFieldParts.Count > 0)
{
foreach (string searchFieldPart in allFieldParts)
{
// is Type a Collection
if (typeof(IEnumerable).IsAssignableFrom(member.Type) && member.Type != typeof(string))
{
isCriteriaCollection = true;
expression = GetCollectionExpression(parameter.Type,
member.Type.GenericTypeArguments.First(), parameter, allFieldParts[allFieldParts.IndexOf(searchFieldPart) - 1],
searchCriteria);
}
else
{
member = Expression.Property(member, searchFieldPart);
}
}
// When no Collection
if (!isCriteriaCollection)
{
// Add values
foreach (var value in searchCriteria.Values)
{
constants.Add(Expression.Constant(value));
}
expression = ExpressionCreator.GetExpression(searchCriteria.OperationType, member, constants);
}
}
else
{
// Add values
foreach (var value in searchCriteria.Values)
{
constants.Add(Expression.Constant(value));
}
expression = ExpressionCreator.GetExpression(searchCriteria.OperationType, member, constants);
}
return(expression);
}
private static Expression GetCollectionExpression(Type mainEntityType, Type subEntityType, ParameterExpression mainType,
string collectionProperty, SearchCriteriaDomainModel searchCriteria)
{
if (mainEntityType == null)
{
throw new NullReferenceException(nameof(mainEntityType));
}
if (subEntityType == null)
{
throw new NullReferenceException(nameof(subEntityType));
}
var fieldName = searchCriteria.FieldName.Split('.').Last();
var constants = new List <ConstantExpression>();
var baseTypeSubEntity = Expression.Parameter(subEntityType, "s");
if (fieldName != null)
{
Expression member = Expression.Property(baseTypeSubEntity, subEntityType.GetProperty(fieldName));
// add Value
foreach (var value in searchCriteria.Values)
{
constants.Add(Expression.Constant(value));
}
// Lambda for Subentities
var innerWhereExpression = ExpressionCreator.GetExpression(searchCriteria.OperationType, member, constants);
var innerWhereFunction = Expression.Lambda(innerWhereExpression, baseTypeSubEntity);
var methodWithAnySelection =
typeof(Enumerable).GetMethods()
.Single(m => m.Name == "Any" && m.GetParameters().Length == 2)
.MakeGenericMethod(subEntityType);
if (collectionProperty != null)
{
var whereExpressionOnCollectionProperty = Expression.Call(methodWithAnySelection,
Expression.Property(mainType, mainEntityType.GetProperty(collectionProperty)), innerWhereFunction);
return(whereExpressionOnCollectionProperty);
}
throw new NullReferenceException(nameof(collectionProperty));
}
throw new NullReferenceException(nameof(fieldName));
}
