private static DTOLambdaAndType GenerateSelector <TEntity>(String propertyName) where TEntity : class
{
DTOLambdaAndType resultset = new DTOLambdaAndType();
var parameter = Expression.Parameter(typeof(TEntity), "Entity");
PropertyInfo property;
Expression propertyAccess;
if (propertyName.Contains('.'))
{
String[] childProperties = propertyName.Split('.');
property = typeof(TEntity).GetProperty(childProperties[0], BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
propertyAccess = Expression.MakeMemberAccess(parameter, property);
for (int i = 1; i < childProperties.Length; i++)
{
property = property.PropertyType.GetProperty(childProperties[i], BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
propertyAccess = Expression.MakeMemberAccess(propertyAccess, property);
}
}
else
{
property = typeof(TEntity).GetProperty(propertyName, BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
propertyAccess = Expression.MakeMemberAccess(parameter, property);
}
resultset.resultType = property.PropertyType;
resultset.lambdaExpression = Expression.Lambda(propertyAccess, parameter);
return(resultset);
}
private static MethodCallExpression GenerateMethodCall <TEntity>(IQueryable <TEntity> source, string methodName, String fieldName) where TEntity : class
{
MethodCallExpression resultExp = null;
Type type = typeof(TEntity);
Type selectorResultType;
DTOLambdaAndType result = new DTOLambdaAndType();
result = GenerateSelector <TEntity>(fieldName);
LambdaExpression selector = result.lambdaExpression;
selectorResultType = result.resultType;
resultExp = Expression.Call(typeof(Queryable), methodName,
new Type[] { type, selectorResultType },
source.Expression, Expression.Quote(selector));
return(resultExp);
}