Develop Reference

Set Object null if all its properties are null in C#

I want to write a function which it turns every properies and child properties of an object. And if all properties of one property are null, then I will set that property as null. I will explain with one example.
For example, if both TeacherName and TeacherSurname are null then I want to set Teacher to null. Then, if ExamMark and ExamName and Teacher are null, then Exam will be null.
You can see json version of like my question from this link Json Version
public class Student
{
public string Name { get; set; }
public string Surname { get; set; }
public Address Address { get; set; }
public Exam Exam { get; set; }
}
public class Exam
{
public string ExamMark { get; set; }
public string ExamName { get; set; }
public Teacher Teacher { get; set; }
}
public class Teacher
{
public string TeacherName { get; set; }
public string TeacherSurname { get; set; }
}
public class Address
{
public string Country { get; set; }
public string City { get; set; }
}
I wrote this method. But this doing only first step. But I need recursive for child class. How can I convert this method to recursive?
public static object ConvertToNull(object obj)
{
Type objType = obj.GetType();
PropertyInfo[] properties = objType.GetProperties();
var mainClassProperties = properties.Where(p => p.PropertyType.Assembly == objType.Assembly);
foreach (var mainClassProperty in mainClassProperties)
{
object propValue = mainClassProperty.GetValue(obj, null);
var classAllProperties = propValue.GetType().GetProperties();
if (propValue.GetType().GetProperties().All(propertyInfo => propertyInfo.GetValue(propValue) == null))
{
mainClassProperty.SetValue(obj, null);
}
}
return obj;
}

What you're asking for is actually an anti-pattern. What this does is it propagates the requirement for tons of null checks in your code. Not only do you have to check if all properties are null, you also have to check if your object is null when you want to use it. Also reflection is very slow and if you're doing this often, you'll bog down your application.
You should look into the Null Object Pattern. It basically does what you want it to, and you remove all those pesky null checks:
public class Student
{
public string Name { get; set; }
public string Surname { get; set; }
public Address Address { get; set; }
public Exam Exam { get; set; }
public static Student NullStudent { get; } = new Student
{
Name = null,
Surname = null,
Address = Address.NullAddress,
Exam = Exam.NullExam,
}
}
You can do this for each object in your code that acts this way (you can see that I did it on your nested Address and Exam types as well) and then instead of doing this:
if (Student.EverythingIsNull) { Student = null }
if (Student is null) { //do null stuff }
You can do this:
if (item == Student.NullStudent) { //do null stuff }
This leads to clearer code, your intent stands out more, and you can specifically define in each object what constitutes as null.

using Generics and Reflection.
public T ConvertToNull<T>(T model) where T : class
{
if (model == null) return null;
Type type = model.GetType();
PropertyInfo[] properties = type.GetProperties();
var valueTypes = properties.Where(p => p.PropertyType.Assembly != type.Assembly);
var nonValueTypes = properties.Where(p => p.PropertyType.Assembly == type.Assembly);
foreach (var nonValueType in nonValueTypes)
nonValueType.SetValue(model, ConvertToNull(nonValueType.GetValue(model)));
if (valueTypes.All(z => z.GetValue(model) == null) && nonValueTypes.All(z => z.GetValue(model) == null))
return null;
else
return model;
}
Here you can call it
List<Student> students = new List<Student>();
Student student = new Student() { Name = "StudentName", Surname = "StudentSurname", Address = new Address() { City = "City", Country = "Country" }, Exam = new Exam() { ExamMark = "ExamMark", ExamName = "ExamName", Teacher = new Teacher() { TeacherName = "TeacherName", TeacherSurname = "TeacherSurname" } } };
Student student2 = new Student() { Name = "StudentName", Surname = "StudentSurname", Address = new Address(), Exam = new Exam() { ExamMark = "ExamMark", ExamName = "ExamName", Teacher = new Teacher() } };
students.Add(student);
students.Add(student2);
List<Student> results = new List<Student>();
foreach (var item in students)
{
var result = ConvertToNull(item);
results.Add(result);
}

Have a look at this The GetValueOrNull should work and do what you need, not tested with all possible use cases but it oculd be tweaked a little if doesn't work in all cases
public static bool IsSimpleType(Type type)
{
return
type.IsPrimitive ||
new Type[] {
typeof(Enum),
typeof(String),
typeof(Decimal),
typeof(DateTime),
typeof(DateTimeOffset),
typeof(TimeSpan),
typeof(Guid)
}.Contains(type) ||
Convert.GetTypeCode(type) != TypeCode.Object ||
(type.IsGenericType && type.GetGenericTypeDefinition() == typeof(Nullable<>) && IsSimpleType(type.GetGenericArguments()[0]))
;
}
public object GetValueOrNull(object obj)
{
if (obj == null) return null;
Type objType = obj.GetType();
PropertyInfo[] properties = objType.GetProperties();
var simpleTypes = properties.Where(t => IsSimpleType(t.PropertyType));
var nonValueTypes = properties.Where(p => !simpleTypes.Contains(p));
foreach (var child in nonValueTypes)
{
child.SetValue(obj, GetValueOrNull(child.GetValue(obj)));
}
return simpleTypes.All(z => z.GetValue(obj) == null) && nonValueTypes.All(z => z.GetValue(obj) == null) ? null : obj;
}
call it as follows
var student = new Student { Address = new Address { }, Exam = new Exam { Teacher = new Teacher() } };
var test = GetValueOrNull(student);
hope it helps :)

Nested List — Get list item of parent list

i want to write a C# function which returns "alamaba" when i pass "Montgomery".
2nd example: Sitka --> Alaska
here is the list of the example:
List<PopulationUSA> result = new List<PopulationUSA>();
PopulationUSA usa = new PopulationUSA("Population in USA", 316128839, new List<PopulationUSA>());
result.Add(usa);
PopulationUSA alabama = new PopulationUSA("Alabama", 4833722, new List<PopulationUSA>());
usa.Items.Add(alabama);
alabama.Items.Add(new PopulationUSA("Birmingham", 212113, null));
alabama.Items.Add(new PopulationUSA("Montgomery", 201332, null));
alabama.Items.Add(new PopulationUSA("Mobile", 194899, null));
PopulationUSA alaska = new PopulationUSA("Alaska", 735132, new List<PopulationUSA>());
usa.Items.Add(alaska);
alaska.Items.Add(new PopulationUSA("Juneau", 32660, null));
alaska.Items.Add(new PopulationUSA("Ketchikan", 8214, null));
alaska.Items.Add(new PopulationUSA("Sitka", 9020, null));
here is the class:
public class PopulationUSA
{
public PopulationUSA(string name, int value, List<PopulationUSA> items)
{
Name = name;
Value = value;
Items = items;
}
public string Name { get; set; }
public int Value { get; set; }
public List<PopulationUSA> Items { get; set; }
}
How can i do that?
Thanks

you can add this method to the PopulationUSA class
public string FindParentsOfGrandChildren(string _name)
{
List<PopulationUSA> parents = Items.Where(s => s.Items.Any(c => c.Name == _name)).ToList();
if (parents != null)
{
string listparents = string.Empty;
for (int i = 0; i < parents.Count; i++)
{
if (i == 0)
{
listparents += parents[i].Name;
}
else
{
listparents += ", " + parents[i].Name;
}
}
return listparents;
}
else
{
return "Not found";
}
}
then use it like this in your example:
string WhereDoIBelong = usa.FindParentsOfGrandChildren("Montgomery")
it would be much better as a recursive method, finding parents of any type (not just "grandchildren") but that is your work!

Cartesian Product of Anonymous type

I am working on code which will give Cartesian product of two anonymous types. These 2 anonymous types are generated from database.
Code for 1st anonymous type:
private IEnumerable<object> GetItem()
{
return _unitOfWork.GetRepository<Item>()
.ListAll()
.Select(x => new
{
itemId = x.Id,
itemName = x.Name
})
}
Code for 2nd anonymous type:
private IEnumerable<object> GetVenue()
{
return _unitOfWork.GetRepository<Venue>()
.ListAll()
.Select(x => new
{
locationName = x.Address.City,
venueId = x.VenueId,
venueName = x.Name
})
}
I have following method to get the data and perform Cartesian product and return the data.
public object GetRestrictLookupInfo(IEnumerable<int> lookupCombinations)
{
IEnumerable<object> restrictList = new List<object>();
if (lookupCombinations.Contains(1))
{
var tempProductProfileList = GetItem();
restrictList = tempProductProfileList.AsEnumerable();
}
if (lookupCombinations.Contains(2))
{
var tempProductGroupList = GetVenue();
restrictList = (from a in restrictList.AsEnumerable()
from b in tempProductGroupList.AsEnumerable()
select new { a, b });
}
return restrictList;
}
I have controller which calls this method and return data in json format.
Controller Code
public HttpResponseMessage GetData(IEnumerable<int> lookupCombinations)
{
var lookupRestrictInfo = _sellerService.GetRestrictLookupInfo(lookupCombinations);
return Request.CreateResponse(HttpStatusCode.OK, lookupRestrictInfo);
}
Response expected is:-
[ {
"itemId": 1,
"itemName": "Music",
"locationName": "Paris",
"venueId": 99,
"venueName": "Royal Festival Hall"
} ]
Response which I receive is
[ {
"a": {
"itemId": 1,
"itemName": "Music"
},
"b": {
"locationName": "Paris",
"venueId": 99,
"venueName": "Royal Festival Hall" } }]
I am not able to get the expected JSON string.

You should start with the simplest possible code that shows your problem; your code above has a lot of complexities that may (or may not) have anything to do with your problem. Is this about manipulating anonymous types? Doing a Cartesian product with LINQ? Converting an object to JSON?
Here's one possible answer to what you might be looking for; notice that you can pass around anonymous types using generics instead of object.
namespace AnonymousTypes
{
class Program
{
static string Serialize(object o)
{
var d = (dynamic)o;
return d.ItemId.ToString() + d.ItemName + d.VenueId.ToString() + d.LocationName + d.VenueName;
}
static string GetData<T>(IEnumerable<T> result)
{
var retval = new StringBuilder();
foreach (var r in result)
retval.Append(Serialize(r));
return retval.ToString();
}
static string GetRestrictLookupInfo()
{
var restrictList = new[] { new { Id = 1, Name = "Music" }, new { Id = 2, Name = "TV" } };
var tempProductGroupList = new[] { new { LocationName = "Paris", Id = 99, Name = "Royal Festival Hall" } };
var result = from item in restrictList
from venue in tempProductGroupList
select new
{
ItemId = item.Id,
ItemName = item.Name,
LocationName = venue.LocationName,
VenueId = venue.Id,
VenueName = venue.Name
};
return GetData(result);
}
public static string GetData()
{
return GetRestrictLookupInfo();
}
static void Main(string[] args)
{
var result = GetData();
}
}
}
If that's not what you're looking for, you might start with code that doesn't use anonymous types, such as
namespace AnonymousTypes
{
sealed class Item
{
public int Id { get; set; }
public string Name { get; set; }
}
sealed class Venue
{
public string LocationName { get; set; }
public int Id { get; set; }
public string Name { get; set; }
}
sealed class ItemAndVenue
{
public int ItemId { get; set; }
public string ItemName { get; set; }
public string LocationName { get; set; }
public int VenueId { get; set; }
public string VenueName { get; set; }
}
class Program
{
static IEnumerable<Item> GetItem()
{
return new[] { new Item { Id = 1, Name = "Music" } };
}
static IEnumerable<Venue> GetVenue()
{
return new[] { new Venue { LocationName = "Paris", Id = 99, Name = "Royal Festival Hall" } };
}
static IEnumerable<ItemAndVenue> GetRestrictLookupInfo()
{
var restrictList = GetItem();
var tempProductGroupList = GetVenue();
var result = from item in restrictList
from venue in tempProductGroupList
select new ItemAndVenue
{
ItemId = item.Id,
ItemName = item.Name,
LocationName = venue.LocationName,
VenueId = venue.Id,
VenueName = venue.Name
};
return result;
}
static string GetData()
{
var v = GetRestrictLookupInfo().First();
return v.ItemId.ToString() + v.ItemName + v.VenueId.ToString() + v.LocationName + v.VenueName;
}
static void Main(string[] args)
{
var result = GetData();
}
}
}

In order to produce a single item in the output you need to create a new type, named or anonymous. Since you are using objects rather than actual types, the quickest approach is to cast them to dynamic:
var tempProductGroupList = GetVenue();
restrictList = (from a in restrictList.Cast<dynamic>()
from b in tempProductGroupList.Cast<dynamic>()
select new {
itemId = (int)a.itemId,
itemName = (string)a.itemName,
locationName = (string)b.locationName,
venueId = (int)b.venueId,
venueName = (string)b.venueName
});
This code is tightly coupled to the code producing both lists, because it assumes the knowledge of the field names of types passed into it dynamically. Any change in the structure of source data must be followed by a change in the code making combinations. In addition, it defeats run-time checking, so you need to be very careful with this code.

Try to create a simple object instead of nesting:
select new { a.itemId, a.itemName, b.locationName }

Like an option:
public object GetRestrictLookupInfo(IEnumerable<int> lookupCombinations)
{
List<Dictionary<string, object>> result = new List<Dictionary<string, object>>();
if (lookupCombinations.Contains(1))
{
var tmp = _unitOfWork.GetRepository<Item>()
.ListAll()
.Select(x => new
{
itemId = x.Id,
itemName = x.Name
})
.Select(x =>
{
var dic = new Dictionary<string, object>();
dic.Add(nameof(x.itemId), x.itemId);
dic.Add(nameof(x.itemName), x.itemName);
return dic;
});
result.AddRange(tmp);
}
if (lookupCombinations.Contains(2))
{
var tmp = _unitOfWork.GetRepository<Venue>()
.ListAll()
.Select(x => new
{
locationName = x.Address.City,
venueId = x.VenueId,
venueName = x.Name
})
.Select(x =>
{
var dic = new Dictionary<string, object>();
dic.Add(nameof(x.locationName), x.locationName);
dic.Add(nameof(x.venueId), x.venueId);
dic.Add(nameof(x.venueName), x.venueName);
return dic;
});
result = result.SelectMany(r => tmp.Select(t => r.Concat(t)));
}
return result;
}
It looks like some magic. I uses dictionary instead of object. It can be make in more clear way (extract few methods), but the idea should be clear.
Then, during serialization it will be presented as you need.

Dynamically build an object from a strongly typed class using C#?

Currently, am adding the properties and values to the object manually like this example and sending to Dapper.SimpleCRUD to fetch data from Dapper Orm. This is the desired output I would like to achieve.
object whereCriteria = null;
whereCriteria = new
{
CountryId = 2,
CountryName = "Anywhere on Earth",
CountryCode = "AOE",
IsActive = true
};
The following class should build the object in the above mentioned format and return the ready-made object.
public static class WhereClauseBuilder
{
public static object BuildWhereClause(object model)
{
object whereObject = null;
var properties = GetProperties(model);
foreach (var property in properties)
{
var value = GetValue(property, model);
//Want to whereObject according to the property and value. Need help in this part!!!
}
return whereObject;
}
private static object GetValue(PropertyInfo property, object model)
{
return property.GetValue(model);
}
private static IEnumerable<PropertyInfo> GetProperties(object model)
{
return model.GetType().GetProperties();
}
}
This function WhereClauseBuilder.BuildWhereClause(object model) should return the object in expected format (mentiond above). Here is the implementation of how I would like to use.
public sealed class CountryModel
{
public int CountryId { get; set; }
public string CountryName { get; set; }
public string CountryCode { get; set; }
public bool IsActive { get; set; }
}
public class WhereClauseClass
{
public WhereClauseClass()
{
var model = new CountryModel()
{
CountryCode = "AOE",
CountryId = 2,
CountryName = "Anywhere on Earth",
IsActive = true
};
//Currently, won't return the correct object because the implementation is missing.
var whereClauseObject = WhereClauseBuilder.BuildWhereClause(model);
}
}

Maybe something like that:
private const string CodeTemplate = #"
namespace XXXX
{
public class Surrogate
{
##code##
}
}";
public static Type CreateSurrogate(IEnumerable<PropertyInfo> properties)
{
var compiler = new CSharpCodeProvider();
var compilerParameters = new CompilerParameters { GenerateInMemory = true };
foreach (var item in AppDomain.CurrentDomain.GetAssemblies().Where(x => !x.IsDynamic))
{
compilerParameters.ReferencedAssemblies.Add(item.Location);
}
var propertiesCode =
string.join("\n\n", from pi in properties
select "public " + pi.PropertyType.Name + " " + pi.Name + " { get; set; }");
var source = CodeTemplate.Replace("##code##", propertiesCode);
var compilerResult = compiler.CompileAssemblyFromSource(compilerParameters, source);
if (compilerResult.Errors.HasErrors)
{
throw new InvalidOperationException(string.Format("Surrogate compilation error: {0}", string.Join("\n", compilerResult.Errors.Cast<CompilerError>())));
}
return compilerResult.CompiledAssembly.GetTypes().First(x => x.Name == "Surrogate");
}
And now use it:
public static object BuildWhereClause(object model)
{
var properties = GetProperties(model);
var surrogateType = CreateSurrogate(properties);
var result = Activator.CreateInstance(surrogateType);
foreach (var property in properties)
{
var value = GetValue(property, model);
var targetProperty = surrogateType.GetProperty(property.Name);
targetProperty.SetValue(result, value, null);
}
return result;
}
I didn't compile that. It's only written here. Maybe there are some errors. :-)
EDIT:
To use ExpandoObject you can try this:
public static object BuildWhereClause(object model)
{
var properties = GetProperties(model);
var result = (IDictionary<string, object>)new ExpandoObject();
foreach (var property in properties)
{
var value = GetValue(property, model);
result.Add(property.Name, value);
}
return result;
}
But I don't know whether this will work for you.

Create distinct expando object list

I have created a method which will create dynamic object list from an object list according to property list. In this case I have completed such task using Expandoobject. But I have failed to create distinct list of such expando object list. Please visit the following fidder and see my code.
public class Program
{
public static void Main()
{
var _dynamicObjectList = new List<Student>();
for (int i = 0; i < 5; i++)
{
_dynamicObjectList.Add(new Student { ID = i, Name = "stu" + i, Address = "address" + i, AdmissionDate = DateTime.Now.AddDays(i) , Age=15, FatherName="Jamal"+i, MotherName = "Jamila"+i});
}
//create again for checking distinct list
for (int i = 0; i < 5; i++)
{
_dynamicObjectList.Add(new Student { ID = i, Name = "stu" + i, Address = "address" + i, AdmissionDate = DateTime.Now.AddDays(i), Age = 15, FatherName = "Jamal" + i, MotherName = "Jamila" + i });
}
// var returnList = test2.GetDdlData<Object>(_dynamicObjectList, "ID,Name,Address");
// var returnList = test2.GetDdlData<Object>(_dynamicObjectList, "ID,FatherName,Address");
var returnList = test2.GetDdlData<Object>(_dynamicObjectList, "ID,Name,FatherName,MotherName,Age");
string strSerializeData = JsonConvert.SerializeObject(returnList);
Console.WriteLine(strSerializeData);
Console.ReadLine();
}
}
public class Student
{
public int? ID { get; set; }
public string Name { get; set; }
public string Address { get; set; }
public DateTime AdmissionDate { get; set; }
public string FatherName { get; set; }
public string MotherName { get; set; }
public int Age { get; set; }
}
public static class test2
{
public static IList GetDdlData<T>(this IEnumerable<T> source, string userParams)
{
try
{
List<string> otherProperties = userParams.Split(',').ToList();
Dictionary<string, PropertyInfo> parentPropertyInfo = new Dictionary<string, PropertyInfo>();
Dictionary<string, Type> parentType = new Dictionary<string, Type>();
var dynamicObjectList = (from k in source select k).ToList();
if (dynamicObjectList.Count() > 0)
{
//if parentField exists then system will handle parent property
if (otherProperties.Count > 0)
{
foreach (string otherProperty in otherProperties)
{
//get parent field property info
PropertyInfo _info = dynamicObjectList[0].GetType().GetProperty(otherProperty);
parentPropertyInfo.Add(otherProperty, _info);
//get parent field propertyType
Type pType = Nullable.GetUnderlyingType(_info.PropertyType) ?? _info.PropertyType;
parentType.Add(otherProperty, pType);
}
}
}
//return List
IList<object> objList = new List<object>();
foreach (T obj in source)
{
var dynamicObj = new ExpandoObject() as IDictionary<string, Object>;
foreach (string otherProperty in otherProperties)
{
PropertyInfo objPropertyInfo = parentPropertyInfo.FirstOrDefault(m => m.Key == otherProperty).Value;
Type objPropertyType = parentType.FirstOrDefault(m => m.Key == otherProperty).Value;
Object data = (objPropertyInfo.GetValue(obj, null) == null) ? null : Convert.ChangeType(objPropertyInfo.GetValue(obj, null), objPropertyType, null);
dynamicObj.Add(otherProperty, data);
}
objList.Add(dynamicObj);
}
var returnUniqList = objList.Distinct().ToList();
return returnUniqList;
}
catch (Exception ex)
{
throw ex;
}
}
}
https://dotnetfiddle.net/hCuJwD

Just add the following code in the code block.
foreach(var objTemp in objList) {
bool isNotSimilar = true;
foreach(string property in otherProperties) {
//get sending object property data
object tempFValue = (objTemp as IDictionary < string, Object > )[property];
//get current object property data
object tempCValue = (dynamicObj as IDictionary < string, Object > )[property];
if (!tempFValue.Equals(tempCValue)) {
isNotSimilar = false;
break;
}
}
if (isNotSimilar) {
isDuplicate = true;
break;
}
}
DOTNETFIDDLE