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How can I set a List<foo> field of an object with the value of List<dynamic>

I have been trying to set some field values of specific objects in C#.
For other reasons I need to construct a List of values from a string then I want to assign this to a field in an object.
The way I indicate the value type of the list is something like this in string
name:type{listItemName:listItemType{listItemValue}}
This list can be of any type, so it is undetermined until we reach conversion.
I am using
List<dynamic> ldy = new List<dynamic>();
foreach (string listElement in listElements)
{
if (listElement == "") continue;
Type leDataType = GetDataType(listElement);
string leData = GetDataRaw(listElement);
var leDynamic = ConstructDataObject(leDataType, leData, listElement);
ldy.Add(leDynamic);
}
Which ends up with the correct data and with the correct data type when I enquire, however when I am trying to use the resulting ldy list and assign it to a field, of course it acts as a List<object>
thus not allowing me to assign.
Finally so, I am using field.SetValue(targetObject, ldy); to assign the value to the field.
The error message I am getting is
ArgumentException: Object of type 'System.Collections.Generic.List`1[System.Object]' cannot be converted to type 'System.Collections.Generic.List`1[System.Int32]'.
Which to be clear, I do understand and I do understand why, however I dont really see how could I solve this issue, not by solving this nor by changing the fundaments of my code design.
Please help!

As #juharr suggested I have searched for solutions to do this with reflection.
Here is my solution:
private static IList GetTypedList(Type t)
{
var listType = typeof(List<>);
var constructedListType = listType.MakeGenericType(t);
var instance = Activator.CreateInstance(constructedListType);
return (IList)instance;
}

Get properties from dynamic object using startswith

I want to get all properties from json that StartsWith particular text
dynamic results = JsonConvert.DeserializeObject<dynamic>(json);
So now below is what i get in results
{"abc" : "Text", "abcde" : "Text2","prop" : "myprop"}
Is it possible to do something like
results.Where(x => x.StartsWith("abc"))

You could simply use results.GetType().GetProperties(), which will give you an array of properties present in the deserialized JSON object.
You could then iterate over that array to get the PropertyInfo objects whose Name starts with whatever string you want, and call GetValue() to obtain the properties' values of interest.
Or you simply don't deserialize at all, but parse the object and treat it as JSON:
var jObject = JObject.Parse(jsonString);
foreach (var rootProperty in jObject)
{
if (rootProperty.Key.StartsWith("whatever"))
{
var valueOfInterest = rootProperty.Value;
}
}

Simply retrieve the runtime-type of the result-object and query its properties using Type.GetProperties:
var type = results.GetType();
type.GetProperties().Where(x => x.Name.StartsWith("abc"));
EDIT: Because any method called on an instance of dynamic is dynamic as well, you have to cast the result of results.GetType into Type. Otherwise you´ll get a compiler-err stating that you can´t use an anonymous method on a dynamically bound operation.
var type = (Type)results.GetType();

How to use the properties of a passed list of known objects

this might be a simple fix but I can't seem to find anything about it. I am very new to C# if it's not obvious.
I'm passing a list of objects from my main method but I haven't been able to use the properties of the objects. I want to use a property called "Asset" This is my code:
private void GetDueDates(List<object> objects)
{
Type myType = objects.GetType();
IList<PropertyInfo> props = new List<PropertyInfo>(myType.GetProperties());
if(props.Contains(Asset)
{
doStuff();
}
}
I thought if I got the type of object then I could use the correct property but that didn't work. Do I even need to find which type it is?

Asset isn't a valid expression here, unless you've actually got a variable called Asset somewhere. You want to find out if the name of any property is Asset... and you want to do it on each object, not on the list itself:
foreach (var item in objects)
{
var props = item.GetType().GetProperties();
var assetProperty = props.FirstOrDefault(p => p.Name == "Asset");
if (assetProperty != null)
{
var value = assetProperty.GetValue(item, null);
// Do stuff...
}
}
Alternatively, if you're only looking for a public property, you can pass the name to GetProperty:
foreach (var item in objects)
{
var assetProperty = item.GetType().GetProperty("Asset");
if (assetProperty != null)
{
var value = assetProperty.GetValue(item, null);
// Do stuff...
}
}
Having said this, it would be cleaner if you had an interface or something similar:
var assetItems = objects.OfType<IHasAsset>();
foreach (var assetItem in assetItems)
{
var asset = assetItem.Asset;
...
}

If you know what type all of the objects in objects should be, then objects should be a list of that type, instead of a list of object (so List<MyType>). At this point, you can simply refer to objects[0].Asset, since all of the objects in the list are of type MyType.
If you still want objects to be a List<object>, then you'll have to typecast each of the objects in the list to a MyType in order to use the Asset property of the MyType class: ((MyType)objects[0]).Asset.
If you do this, and you aren't sure that all of the objects in the list are actually of type MyType, you need to check that:
if (objects[0] is MyType)
{
// do stuff with ((MyType)objects[0]).Asset
}

Looking for a way to dynamically change field names in PropertyGrid

I've got COM object attached to property grid.
Type typeObj = Type.GetTypeFromProgID(progIdService);
var obj = Activator.CreateInstance(typeObj);
propertyGrid1.SelectedObject = obj;
Now I need some way to translate object fields into my language using some translator. I was trying to use wrapper around object but with COM object I have no PropertyInfo, I have only PropertyDescription so I'm still looking for all the possible variants of doing it.

What you could do is reuse the DynamicTypeDescriptor class described in my answer to this question here on SO: PropertyGrid Browsable not found for entity framework created property, how to find it?
like this:
DynamicTypeDescriptor dtp = new DynamicTypeDescriptor(typeObj);
// get current property definition and remove it
var current = dtp.Properties["ThePropertyToChange"];
dtp.RemoveProperty("ThePropertyToChange");
// add a new one, but change its display name
DynamicTypeDescriptor.DynamicProperty prop = new DynamicTypeDescriptor.DynamicProperty(dtp, current, obj);
prop.SetDisplayName("MyNewPropertyName");
dtp.AddProperty(prop);
propertyGrid1.SelectedObject = dtp.FromComponent(obj);

I think you can use reflection to get the property names, although I haven't tried with COM objects yet. Be sure to include the System.Reflection namespace, then you can use it like that:
var props = myComObject.GetType().GetProperties();
foreach (var prop in props)
{
MessageBox(prop.Name);
}

How to iterate properties of two objects dynamically

I have two object of same class, I want to update the p2 with fields which are are in Dirty list. So far I managed to write the following code but struggling to get the value of p1 properties. What object should I pass here as parameter to GetValue method.
Person p1 = new Person();
p1.FirstName = "Test";
Person p2 = new Person();
var allDirtyFields = p1.GetAllDirtyFields();
foreach (var dirtyField in allDirtyFields)
{
p2.GetType()
.GetProperty(dirtyField)
.SetValue(p1.GetType().GetProperty(dirtyField).GetValue());
}
_context.UpdateObject(p2);
_context.SaveChanges();
Thanks in advance.

You should try that:
foreach (var dirtyField in allDirtyFields)
{
var prop = p2.GetType().GetProperty(dirtyField);
prop.SetValue(p2, prop.GetValue(p1));
}
It is a better to store PropertyInfo instance in a variable, then trying to resolve it twice.

Did you know that you don't need to retrieve the property for each object?
Type metadata is common to any object of the whole type.
For example:
// Firstly, get dirty property informations!
IEnumerable<PropertyInfo> dirtyProperties = p2.GetType().GetProperties(BindingFlags.Instance | BindingFlags.Public)
.Where
(
property => allDirtyFields.Any
(
field => property.Name == field
)
);
// Then, just iterate the whole property informations, but give the
// "obj" GetValue/SetValue first argument the references "p2" or "p1" as follows:
foreach(PropertyInfo dirtyProperty in dirtyProperties)
{
dirtyProperty.SetValue(p2, dirtyProperty.GetValue(p1));
}
Check that the first parameter of PropertyInfo.GetValue(...) and PropertyInfo.SetValue(...) is the object for which you want to get or set the value of the whole property.

In each iteration, you have to get a reference to the PropertyInfo. When you call it's SetValue method, you should pass in 2 parameters, the object for which you will set the property and the actual value you are setting. For the latter one, you should invoke the GetValue method on the same property, passing in the p1 object as parameter, i.e. the source for the value.
Try this:
foreach (var dirtyField in allDirtyFields)
{
var p = p2.GetType().GetProperty(dirtyField);
p.SetValue(p2, p.GetValue(p1));
}
I would recommend you to keep the dirtyField variables in a dictionary and retrieve the associated PropertyInfo object from this dictionary. It should be much faster.
Firstly, declare some static variable in your class:
static Dictionary<string, PropertyInfo>
personProps = new Dictionary<string, PropertyInfo>();
Then you may change your method to:
foreach (var dirtyField in allDirtyFields)
{
PropertyInfo p = null;
if (!personProps.ContainsKey(dirtyField))
{
p = p2.GetType().GetProperty(dirtyField);
personProps.Add(dirtyField, p);
}
else
{
p = personProps[dirtyField];
}
p.SetValue(p2, p.GetValue(p1));
}

You need to pass the instance from which you want to get the property value, like so:
p1.GetType().GetProperty(dirtyField).GetValue(p1, null)
The second parameter, can be used to retrieve a value at a certain index if the property type is indexed.

IIrc you send p1 being the instance that holds the value and null to indicate you're not searching for a specific index value.