I want to get the names of all properties that changed for matching objects. I have these (simplified) classes:
public enum PersonType { Student, Professor, Employee }
class Person {
public string Name { get; set; }
public PersonType Type { get; set; }
}
class Student : Person {
public string MatriculationNumber { get; set; }
}
class Subject {
public string Name { get; set; }
public int WeeklyHours { get; set; }
}
class Professor : Person {
public List<Subject> Subjects { get; set; }
}
Now I want to get the objects where the Property values differ:
List<Person> oldPersonList = ...
List<Person> newPersonList = ...
List<Difference> = GetDifferences(oldPersonList, newPersonList);
public List<Difference> GetDifferences(List<Person> oldP, List<Person> newP) {
//how to check the properties without casting and checking
//for each type and individual property??
//can this be done with Reflection even in Lists??
}
In the end I would like to have a list of Differences like this:
class Difference {
public List<string> ChangedProperties { get; set; }
public Person NewPerson { get; set; }
public Person OldPerson { get; set; }
}
The ChangedProperties should contain the name of the changed properties.
I've spent quite a while trying to write a faster reflection-based solution using typed delegates. But eventually I gave up and switched to Marc Gravell's Fast-Member library to achieve higher performance than with normal reflection.
Code:
internal class PropertyComparer
{
public static IEnumerable<Difference<T>> GetDifferences<T>(PropertyComparer pc,
IEnumerable<T> oldPersons,
IEnumerable<T> newPersons)
where T : Person
{
Dictionary<string, T> newPersonMap = newPersons.ToDictionary(p => p.Name, p => p);
foreach (T op in oldPersons)
{
// match items from the two lists by the 'Name' property
if (newPersonMap.ContainsKey(op.Name))
{
T np = newPersonMap[op.Name];
Difference<T> diff = pc.SearchDifferences(op, np);
if (diff != null)
{
yield return diff;
}
}
}
}
private Difference<T> SearchDifferences<T>(T obj1, T obj2)
{
CacheObject(obj1);
CacheObject(obj2);
return SimpleSearch(obj1, obj2);
}
private Difference<T> SimpleSearch<T>(T obj1, T obj2)
{
Difference<T> diff = new Difference<T>
{
ChangedProperties = new List<string>(),
OldPerson = obj1,
NewPerson = obj2
};
ObjectAccessor obj1Getter = ObjectAccessor.Create(obj1);
ObjectAccessor obj2Getter = ObjectAccessor.Create(obj2);
var propertyList = _propertyCache[obj1.GetType()];
// find the common properties if types differ
if (obj1.GetType() != obj2.GetType())
{
propertyList = propertyList.Intersect(_propertyCache[obj2.GetType()]).ToList();
}
foreach (string propName in propertyList)
{
// fetch the property value via the ObjectAccessor
if (!obj1Getter[propName].Equals(obj2Getter[propName]))
{
diff.ChangedProperties.Add(propName);
}
}
return diff.ChangedProperties.Count > 0 ? diff : null;
}
// cache for the expensive reflections calls
private Dictionary<Type, List<string>> _propertyCache = new Dictionary<Type, List<string>>();
private void CacheObject<T>(T obj)
{
if (!_propertyCache.ContainsKey(obj.GetType()))
{
_propertyCache[obj.GetType()] = new List<string>();
_propertyCache[obj.GetType()].AddRange(obj.GetType().GetProperties().Select(pi => pi.Name));
}
}
}
Usage:
PropertyComparer pc = new PropertyComparer();
var diffs = PropertyComparer.GetDifferences(pc, oldPersonList, newPersonList).ToList();
Performance:
My very biased measurements showed that this approach is about 4-6 times faster than the Json-Conversion and about 9 times faster than ordinary reflections. But in fairness, you could probably speed up the other solutions quite a bit.
Limitations:
At the moment my solution doesn't recurse over nested lists, for example it doesn't compare individual Subject items - it only detects that the subjects lists are different, but not what or where. However, it shouldn't be too hard to add this feature when you need it. The most difficult part would probably be to decide how to represent these differences in the Difference class.
We start with 2 simple methods:
public bool AreEqual(object leftValue, object rightValue)
{
var left = JsonConvert.SerializeObject(leftValue);
var right = JsonConvert.SerializeObject(rightValue);
return left == right;
}
public Difference<T> GetDifference<T>(T newItem, T oldItem)
{
var properties = typeof(T).GetProperties();
var propertyValues = properties
.Select(p => new {
p.Name,
LeftValue = p.GetValue(newItem),
RightValue = p.GetValue(oldItem)
});
var differences = propertyValues
.Where(p => !AreEqual(p.LeftValue, p.RightValue))
.Select(p => p.Name)
.ToList();
return new Difference<T>
{
ChangedProperties = differences,
NewItem = newItem,
OldItem = oldItem
};
}
AreEqual just compares the serialized versions of two objects using Json.Net, this keeps it from treating reference types and value types differently.
GetDifference checks the properties on the passed in objects and compares them individually.
To get a list of differences:
var oldPersonList = new List<Person> {
new Person { Name = "Bill" },
new Person { Name = "Bob" }
};
var newPersonList = new List<Person> {
new Person { Name = "Bill" },
new Person { Name = "Bobby" }
};
var diffList = oldPersonList.Zip(newPersonList, GetDifference)
.Where(d => d.ChangedProperties.Any())
.ToList();
Everyone always tries to get fancy and write these overly generic ways of extracting data. There is a cost to that.
Why not be old school simple.
Have a GetDifferences member function Person.
virtual List<String> GetDifferences(Person otherPerson){
var diffs = new List<string>();
if(this.X != otherPerson.X) diffs.add("X");
....
}
In inherited classes. Override and add their specific properties. AddRange the base function.
KISS - Keep it simple. It would take you 10 minutes of monkey work to write it, and you know it will be efficient and work.
I am doing it by using this:
//This structure represents the comparison of one member of an object to the corresponding member of another object.
public struct MemberComparison
{
public static PropertyInfo NullProperty = null; //used for ROOT properties - i dont know their name only that they are changed
public readonly MemberInfo Member; //Which member this Comparison compares
public readonly object Value1, Value2;//The values of each object's respective member
public MemberComparison(PropertyInfo member, object value1, object value2)
{
Member = member;
Value1 = value1;
Value2 = value2;
}
public override string ToString()
{
return Member.name+ ": " + Value1.ToString() + (Value1.Equals(Value2) ? " == " : " != ") + Value2.ToString();
}
}
//This method can be used to get a list of MemberComparison values that represent the fields and/or properties that differ between the two objects.
public static List<MemberComparison> ReflectiveCompare<T>(T x, T y)
{
List<MemberComparison> list = new List<MemberComparison>();//The list to be returned
if (x.GetType().IsArray)
{
Array xArray = x as Array;
Array yArray = y as Array;
if (xArray.Length != yArray.Length)
list.Add(new MemberComparison(MemberComparison.NullProperty, "array", "array"));
else
{
for (int i = 0; i < xArray.Length; i++)
{
var compare = ReflectiveCompare(xArray.GetValue(i), yArray.GetValue(i));
if (compare.Count > 0)
list.AddRange(compare);
}
}
}
else
{
foreach (PropertyInfo m in x.GetType().GetProperties())
//Only look at fields and properties.
//This could be changed to include methods, but you'd have to get values to pass to the methods you want to compare
if (!m.PropertyType.IsArray && (m.PropertyType == typeof(String) || m.PropertyType == typeof(double) || m.PropertyType == typeof(int) || m.PropertyType == typeof(uint) || m.PropertyType == typeof(float)))
{
var xValue = m.GetValue(x, null);
var yValue = m.GetValue(y, null);
if (!object.Equals(yValue, xValue))//Add a new comparison to the list if the value of the member defined on 'x' isn't equal to the value of the member defined on 'y'.
list.Add(new MemberComparison(m, yValue, xValue));
}
else if (m.PropertyType.IsArray)
{
Array xArray = m.GetValue(x, null) as Array;
Array yArray = m.GetValue(y, null) as Array;
if (xArray.Length != yArray.Length)
list.Add(new MemberComparison(m, "array", "array"));
else
{
for (int i = 0; i < xArray.Length; i++)
{
var compare = ReflectiveCompare(xArray.GetValue(i), yArray.GetValue(i));
if (compare.Count > 0)
list.AddRange(compare);
}
}
}
else if (m.PropertyType.IsClass)
{
var xValue = m.GetValue(x, null);
var yValue = m.GetValue(y, null);
if ((xValue == null || yValue == null) && !(yValue == null && xValue == null))
list.Add(new MemberComparison(m, xValue, yValue));
else if (!(xValue == null || yValue == null))
{
var compare = ReflectiveCompare(m.GetValue(x, null), m.GetValue(y, null));
if (compare.Count > 0)
list.AddRange(compare);
}
}
}
return list;
}
Here you have a code which does what you want with Reflection.
public List<Difference> GetDifferences(List<Person> oldP, List<Person> newP)
{
List<Difference> allDiffs = new List<Difference>();
foreach (Person oldPerson in oldP)
{
foreach (Person newPerson in newP)
{
Difference curDiff = GetDifferencesTwoPersons(oldPerson, newPerson);
allDiffs.Add(curDiff);
}
}
return allDiffs;
}
private Difference GetDifferencesTwoPersons(Person OldPerson, Person NewPerson)
{
MemberInfo[] members = typeof(Person).GetMembers();
Difference returnDiff = new Difference();
returnDiff.NewPerson = NewPerson;
returnDiff.OldPerson = OldPerson;
returnDiff.ChangedProperties = new List<string>();
foreach (MemberInfo member in members)
{
if (member.MemberType == MemberTypes.Property)
{
if (typeof(Person).GetProperty(member.Name).GetValue(NewPerson, null).ToString() != typeof(Person).GetProperty(member.Name).GetValue(OldPerson, null).ToString())
{
returnDiff.ChangedProperties.Add(member.Name);
}
}
}
return returnDiff;
}
Related
As part of a test I am trying to compare similar objects using reflection.
The objects may or may not have multiple levels of nested params.
For example:
public class Connection{
public string Ip{get; set}
public string Id{get; set}
public string Key{get; set}
public string Transport{get; set}
public Parameters ParametersObj = new Parameters();
public class Parameters
{
public string AssignedName { get; set; }
public string CategoryType { get; set; }
public string Status { get; set; }
}
};
This is just an example of a class, I need this method to deal with any type of object without knowing the number of depth level.
I am doing something like this after I have made sure the two objects are of the same type.
bool result = true;
foreach (var objParam in firstObj.GetType().GetProperties())
{
var value1 = objParam.GetValue(firstObj);
var value2 = objParam.GetValue(secondObj);
if (value1 == null || value2 == null || !value1.Equals(value2))
{
logger.Error("Property: " + objParam.Name);
logger.Error("Values: " + value1?.ToString() + " and " + value2?.ToString());
result = false;
}
}
return result;
It works perfectly for the first level of params but it ignores completely any nested objects. In this example I would like it to compare the values inside the parameters object and if they are different the log to print error "Property: Parameters.Status".
I would recommend to look into some tool which already does that (do not know one which does exactly that but FluentAssertions for example can handle object graph comparisons). But in the nutshell you can check if type is primitive or overrides Equals and call your method recursively. Something like the following:
bool Compare(object firstObj, object secondObj)
{
if (object.ReferenceEquals(firstObj, secondObj))
{
return true;
}
var type = firstObj.GetType();
var propertyInfos = firstObj.GetType().GetProperties();
foreach (var objParam in propertyInfos)
{
var methodInfo = objParam.PropertyType.GetMethod(nameof(object.Equals), BindingFlags.Public | BindingFlags.Instance | BindingFlags.DeclaredOnly, new []{typeof(object)});
var overridesEquals = methodInfo?.GetBaseDefinition().DeclaringType == typeof(object);
var value1 = objParam.GetValue(firstObj);
var value2 = objParam.GetValue(secondObj);
if (value1 == null || value2 == null)
{
// Log
return false;
}
if (object.ReferenceEquals(value1, value2))
{
continue;
}
if (type.IsPrimitive || overridesEquals)
{
if (value1.Equals(value2))
{
continue;
}
// Log?
return false;
}
if (!Compare(value1, value2))
{
// log ?
return false;
}
}
return true;
}
P.S.
Note that Connection.ParametersObj is not a property it is field so it will be ignored by both yours and mine implementations
Consider using source generators instead of reflection.
This does not handle collections.
The problem is that you only do one loop, without looking at the objects within each object. Here's a quick recursive function I threw together. (untested!)
// You can make it non-generic, this just ensures that both arguments are the same type.
static void Go<T>(T left, T right, Action<object, object, PropertyInfo> onFound, int depth = 2)
{
if (left is null)
return;
foreach (var p in left.GetType().GetProperties())
{
var l = p.GetValue(left);
var r = p.GetValue(right);
if (l is null || r is null || !l.Equals(r))
onFound(l, r, p);
if (depth is not 0)
Go(l, r, onFound, depth - 1);
}
}
Usage:
var arg1 = new Connection()
{
ParametersObj = new() { AssignedName = "foo" }
};
var arg2 = new Connection()
{
ParametersObj = new() { AssignedName = "bar" }
};
Go(arg1, arg2, Log); // goes 2 layers deep is you don't specify the last parameter
void Log(object l, object r, PropertyInfo p)
{
logger.Error($"Property: {p.Name}");
logger.Error($"Values: {l} and {r}");
}
Following is a class
public class Attribute
{
public string Name { get; set; }
public string Value { get; set; }
}
Following is the code in my main method
{
var test = new List<Attribute>();
test.Add(new Attribute { Name = "Don", Value = "21" });
test.Add(new Attribute { Value = "34", Name = "Karthik" });
var test1 = new List<Attribute>();
test1.Add(new Attribute { Name = "Don", Value = "21" });
test1.Add(new Attribute { Value = "34", Name = "Karthik" });
var obj = new Program();
var areEqual1 = obj.CompareList<List<Attribute>>(test, test1);
}
I have a ComapreList method
public bool CompareList<T>(T firstList, T secondList) where T : class
{
var list1 = firstList as IList<T>;
return true;
}
Now, list1 has null. I know that .net does not allow us to do this. But is there any other way where I can cast this generic list. My purpose is to compare each property value of these two list. I am using reflection to get the property but it works only if I can convert the firstlist/secondlist to something enumerable. if I directly use the name of the class in the IList<> (firstList as IList<Attribute>) it works, but not if I give <T>. Please help.
Just create method parameterized by type of lists items type. Even more, you can create method which compares any type of collections:
public bool CompareSequences<T> (IEnumerable<T> first, IEnumerable<T> second,
Comparer<T> comparer = null)
{
comparer = comparer ?? Comparer<T>.Default;
if (first == null)
throw new ArgumentNullException(nameof(first));
if (second == null)
throw new ArgumentNullException(nameof(second));
var firstIterator = first.GetEnumerator();
var secondIterator = second.GetEnumerator();
while(true)
{
bool firstHasItem = firstIterator.MoveNext();
bool secondHasItem = secondIterator.MoveNext();
if (firstHasItem != secondHasItem)
return false;
if (!firstHasItem && !secondHasItem)
return true;
if (comparer.Compare(firstIterator.Current, secondIterator.Current) != 0)
return false;
}
}
If collection items are primitive types, you can use default comparer. But if collections contain custom items, you need either IComparable to be implemented by collection items type:
public class Attribute : IComparable<Attribute>
{
public string Name { get; set; }
public string Value { get; set; }
public int CompareTo (Attribute other)
{
int result = Name.CompareTo(other.Name);
if (result == 0)
return Value.CompareTo(other.Value);
return result;
}
}
Or you can create and pass comparer instance. You can create comparer which is using reflection to compare fields/properties of some type. But it's not as simple as you might think - properties can be complex type or collections.
Usage:
var areEqual1 = obj.CompareSequences(test, test1);
If you don't need to compare objects with complex structure (which have inner collections and other custom objects) then you can use comparer like this one:
public class SimplePropertiesComparer<T> : Comparer<T>
{
public override int Compare (T x, T y)
{
Type type = typeof(T);
var flags = BindingFlags.GetProperty | BindingFlags.Public | BindingFlags.Instance;
foreach (var property in type.GetProperties(flags))
{
var propertyType = property.PropertyType;
if (!typeof(IComparable).IsAssignableFrom(propertyType))
throw new NotSupportedException($"{propertyType} props are not supported.");
var propertyValueX = (IComparable)property.GetValue(x);
var propertyValueY = (IComparable)property.GetValue(y);
if (propertyValueX == null && propertyValueY == null)
continue;
if (propertyValueX == null)
return -1;
int result = propertyValueX.CompareTo(property.GetValue(y));
if (result == 0)
continue;
return result;
}
return 0;
}
}
And pass it to sequence comparer
var equal = obj.CompareSequences(test, test1, new SimplePropertiesComparer<Attribute>());
Change the signature of your method and remove the then redundant cast:
public bool CompareList<T>(IList<T> firstList, IList<T> secondList) where T : class
{
var list1 = firstList as IList<T>; // Cast is not necessary any more
return true;
}
public bool CompareGenericLists<T, U>(List<T> list1, List<U> list2)
{
try
{
if (typeof(T).Equals(typeof(U)))
{
//For checking null lists
if (list1 == null && list2 == null)
return true;
if (list1 == null || list2 == null)
throw new Exception("One of the Lists is Null");
if (list1.Count.Equals(list2.Count))
{
Type type = typeof(T);
//For primitive lists
if (type.IsPrimitive)
{
int flag = 0;
for (int i = 0; i < list1.Count; i++)
{
if (list1.ElementAt(i).Equals(list2.ElementAt(i)))
flag++;
}
if (flag != list1.Count)
throw new Exception("Objects values are not same");
}
//For Reference List
else
{
for (int i = 0; i < list1.Count; i++)
{
foreach (System.Reflection.PropertyInfo property in type.GetProperties())
{
string Object1Value = string.Empty;
string Object2Value = string.Empty;
Object1Value = type.GetProperty(property.Name).GetValue(list1.ElementAt(i)).ToString();
Object2Value = type.GetProperty(property.Name).GetValue(list2.ElementAt(i)).ToString();
if (Object1Value != Object2Value)
{
throw new Exception("Objects values are not same");
}
}
}
}
}
else
throw new Exception("Length of lists is not Same");
}
else
throw new Exception("Different type of lists");
}
catch(Exception ex)
{
throw ex;
}
return true;
}
this method can be used for both primitive and reference lists.try this method.It will compare type,counts,and members of lists.
I have a class with 3 List collections like the following.
I am trying to have a logic which will iterate through the object's "collection"
properties and do some operation using the data stored in those collections.
I am just wondering if there is an easy way of doing it using foreach.
thanks
public class SampleChartData
{
public List<Point> Series1 { get; set; }
public List<Point> Series2 { get; set; }
public List<Point> Series3 { get; set; }
public SampleChartData()
{
Series1 = new List<Point>();
Series2 = new List<Point>();
Series3 = new List<Point>();
}
}
Function to get all IEnumerable<T> from object:
public static IEnumerable<IEnumerable<T>> GetCollections<T>(object obj)
{
if(obj == null) throw new ArgumentNullException("obj");
var type = obj.GetType();
var res = new List<IEnumerable<T>>();
foreach(var prop in type.GetProperties())
{
// is IEnumerable<T>?
if(typeof(IEnumerable<T>).IsAssignableFrom(prop.PropertyType))
{
var get = prop.GetGetMethod();
if(!get.IsStatic && get.GetParameters().Length == 0) // skip indexed & static
{
var collection = (IEnumerable<T>)get.Invoke(obj, null);
if(collection != null) res.Add(collection);
}
}
}
return res;
}
Then you can use something like
var data = new SampleChartData();
foreach(var collection in GetCollections<Point>(data))
{
foreach(var point in collection)
{
// do work
}
}
to iterate through all elements.
Use Reflection to get the objects Properties. Then iterate over those to see is IEnumerable<T>. Then iterate over the IEnumerable properties
You can use reflection to get the list of properties from the object. This example gets all the properties and prints their name and Count to the console:
public static void PrintSeriesList()
{
SampleChartData myList = new SampleChartData();
PropertyInfo[] Fields = myList.GetType().GetProperties();
foreach(PropertyInfo field in Fields)
{
var currentField = field.GetValue(myList, null);
if (currentField.GetType() == typeof(List<Point>))
{
Console.WriteLine("List {0} count {1}", field.Name, ((List<Point>)currentField).Count);
}
}
}
Just found a quick solution, but maybe some of you have better ways of doing it.
this is what I did.
SampleChartData myData = DataFeed.GetData();
Type sourceType = typeof(SampleChartData);
foreach (PropertyInfo pi in (sourceType.GetProperties()))
{
if (pi.GetValue(myData, null).GetType() == typeof(List<Point>))
{
List<Point> currentSeriesData = (List<Point>)pi.GetValue(myData, null);
// then do something with the data
}
}
I need to calculate a whole bunch of averages on an List of Surveys. The surveys have lots of properties that are int and double valued. I am creating a business object to handle all the calculations (there are like 100) and I'd rather not code 100 different methods for finding the average for a particular property.
I'd like to be able to have the UI pass a string (representing the property) and have the the business object return an average for that property.
So, like...
int AverageHeightInInches = MyObject.GetIntAverage("HeightInInches");
.
.
.
Then have linq code to calculate the result.
Thanks!
I have created this little example, it uses the System.Linq.Expression namespace to create a function that can calculate averages based on the property name. The function can be cached for later use, reflection is only used to create the function, not each time the function is executed.
EDIT: I removed the existing reflection example and updated the current example to show the ability to walk a list of properties.
static class Program
{
static void Main()
{
var people = new List<Person>();
for (var i = 0; i < 1000000; i++)
{
var person = new Person { Age = i };
person.Details.Height = i;
person.Details.Name = i.ToString();
people.Add(person);
}
var averageAgeFunction = CreateIntegerAverageFunction<Person>("Age");
var averageHeightFunction = CreateIntegerAverageFunction<Person>("Details.Height");
var averageNameLengthFunction = CreateIntegerAverageFunction<Person>("Details.Name.Length");
Console.WriteLine(averageAgeFunction(people));
Console.WriteLine(averageHeightFunction(people));
Console.WriteLine(averageNameLengthFunction(people));
}
public static Func<IEnumerable<T>, double> CreateIntegerAverageFunction<T>(string property)
{
var type = typeof(T);
var properties = property.Split('.'); // Split the properties
ParameterExpression parameterExpression = Expression.Parameter(typeof(T));
Expression expression = parameterExpression;
// Iterrate over the properties creating an expression that will get the property value
for (int i = 0; i < properties.Length; i++)
{
var propertyInfo = type.GetProperty(properties[i]);
expression = Expression.Property(expression, propertyInfo); // Use the result from the previous expression as the instance to get the next property from
type = propertyInfo.PropertyType;
}
// Ensure that the last property in the sequence is an integer
if (type.Equals(typeof(int)))
{
var func = Expression.Lambda<Func<T, int>>(expression, parameterExpression).Compile();
return c => c.Average(func);
}
throw new Exception();
}
}
public class Person
{
private readonly Detials _details = new Detials();
public int Age { get; set; }
public Detials Details { get { return _details; } }
}
public class Detials
{
public int Height { get; set; }
public string Name { get; set; }
}
Here is an example to do that.
class Survey
{
public int P1 { get; set; }
}
class MyObject
{
readonly List<Survey> _listofSurveys = new List<Survey> { new Survey { P1 = 10 }, new Survey { P1 = 20 } };
public int GetIntAverage(string propertyName)
{
var type = typeof(Survey);
var property = type.GetProperty(propertyName);
return (int)_listofSurveys.Select(x => (int) property.GetValue(x,null)).Average();
}
}
static void Main(string[] args)
{
var myObject = new MyObject();
Console.WriteLine(myObject.GetIntAverage("P1"));
Console.ReadKey();
}
if you are using linq2sql i would suggest DynamicLinq
you could then just do
datacontext.Surveys.Average<double>("propertyName");
the dynamic linq project provides the string overloads to IQueryable.
You can do this without reflection (both int and double are supported):
public static double Average(this IEnumerable<Survey> surveys, Func<Survey, int> selector)
{
return surveys.Average(selector);
}
public static double Average(this IEnumerable<Survey> surveys, Func<Survey, double> selector)
{
return surveys.Average(selector);
}
Usage:
var average1 = surveys.Average(survey => survey.Property1);
var average2 = surveys.Average(survey => survey.Property2);
I am writing a Clone method using reflection. How do I detect that a property is an indexed property using reflection? For example:
public string[] Items
{
get;
set;
}
My method so far:
public static T Clone<T>(T from, List<string> propertiesToIgnore) where T : new()
{
T to = new T();
Type myType = from.GetType();
PropertyInfo[] myProperties = myType.GetProperties();
for (int i = 0; i < myProperties.Length; i++)
{
if (myProperties[i].CanWrite && !propertiesToIgnore.Contains(myProperties[i].Name))
{
myProperties[i].SetValue(to,myProperties[i].GetValue(from,null),null);
}
}
return to;
}
if (propertyInfo.GetIndexParameters().Length > 0)
{
// Property is an indexer
}
Sorry, but
public string[] Items { get; set; }
is not an indexed property, it's merely of an array type!
However the following is:
public string this[int index]
{
get { ... }
set { ... }
}
What you want is the GetIndexParameters() method. If the array that it returns has more than 0 items, that means it's an indexed property.
See the MSDN documentation for more details.
If you call property.GetValue(obj,null), and the property IS indexed, then you will get a parameter count mismatch exception. Better to check whether the property is indexed using GetIndexParameters() and then decide what to do.
Here is some code that worked for me:
foreach (PropertyInfo property in obj.GetType().GetProperties())
{
object value = property.GetValue(obj, null);
if (value is object[])
{
....
}
}
P.S. .GetIndexParameters().Length > 0) works for the case described in this article: http://msdn.microsoft.com/en-us/library/b05d59ty.aspx
So if you care about the property named Chars for a value of type string, use that, but it does not work for most of the arrays I was interested in, including, I am pretty sure, a string array from the original question.
You can convert the indexer to IEnumerable
public static IEnumerable<T> AsEnumerable<T>(this object o) where T : class {
var list = new List<T>();
System.Reflection.PropertyInfo indexerProperty = null;
foreach (System.Reflection.PropertyInfo pi in o.GetType().GetProperties()) {
if (pi.GetIndexParameters().Length > 0) {
indexerProperty = pi;
break;
}
}
if (indexerProperty.IsNotNull()) {
var len = o.GetPropertyValue<int>("Length");
for (int i = 0; i < len; i++) {
var item = indexerProperty.GetValue(o, new object[]{i});
if (item.IsNotNull()) {
var itemObject = item as T;
if (itemObject.IsNotNull()) {
list.Add(itemObject);
}
}
}
}
return list;
}
public static bool IsNotNull(this object o) {
return o != null;
}
public static T GetPropertyValue<T>(this object source, string property) {
if (source == null)
throw new ArgumentNullException("source");
var sourceType = source.GetType();
var sourceProperties = sourceType.GetProperties();
var properties = sourceProperties
.Where(s => s.Name.Equals(property));
if (properties.Count() == 0) {
sourceProperties = sourceType.GetProperties(BindingFlags.Instance | BindingFlags.NonPublic);
properties = sourceProperties.Where(s => s.Name.Equals(property));
}
if (properties.Count() > 0) {
var propertyValue = properties
.Select(s => s.GetValue(source, null))
.FirstOrDefault();
return propertyValue != null ? (T)propertyValue : default(T);
}
return default(T);
}