I'm wondering if there's any reasonable way to get a reference to an object in Flex, and look through everything in every sub object (every property and everything). That is, I want to know if I can completely map all of the data within an object, from another object. I'm aware that this wouldn't work for private (or protected) members, but for anything public, it should be possible, correct?
Use describeType for class instances, and
for (var str:String in obj) { trace (str+":"+obj[str]); }
for simple Objects.
Related
Is it possible to invoke a method on each object that is being copied from a source to a destination collection using AutoMapper? The destination object has a method called
Decrypt() and I would like it to be called for each CustomerDTO element that is created. The only thing that I can figure out is to perform the mapping conversion and then loop again to invoke the Decrypt() method. I'd appreciate your help with this question.
Thanks,
Mike
IQueryable<CustomerDTO> dtos = AutoMapper.Mapper.Map<IQueryable<CustomerEntity>, IQueryable<CustomerDTO>>((BaseRepository.List));
foreach (var item in dtos)
{
item.Decrypt(Seed);
}
It depends if you are decrypting just a property or the whole object. I wasn't sure based on your question.
If you are just decrypting properties, then I suggest that you look into AutoMapper's Custom Value Resolvers. They allow you to take control when resolving a destination property.
If you need to decrypt the whole object, then I suggest you look into AutoMapper's Custom Type Converters. That gives you complete control over the conversion, though it does sort of take the auto out of AutoMapper.
I found another similar question, but don't quite follow the explanation there, and not sure if it applies the same to me.
I am getting the error:
warning: unable to bind to property 'Description' on class 'Object' (class is not an IEventDispatcher)
this is only when the data is bound to a List as an ArrayList, though. I had it in a Datagrid before (just as an Array) and it did not cause any issue. I'm not expecting to be able to bind any data back to the class 'object' not even sure which object exactly it's referring to.
My list data-provider is an ArrayList.. populated by a result event from an SQL query contained in another class:
private function loadDayComplete():void
{
var Meals:Array = _day.MealResults;
var MealsListResult:ArrayList = new ArrayList(Meals);
MealPanelDataGrid.dataProvider = Meals;
MealListView.dataProvider = MealsListResult;
{
The day class I have is a data holder to get all the data (from several tables) for a 24 hour span.. I have classes for each individual datatype for editing them.
But I'm not sure do I even need to worry about the warning if I don't plan on editing the values? it completely spams the console though whenever I touch anything, so I really would like to get rid of it.
I tried an object proxy as I saw described elsewhere but nothing changed. And I'm pretty confused why it's suddenly an issue on a list component when it wasn't on a datagrid... The text is in label fields right now anyway, which can't even be edited.
The objects causing this warning are probably items inside Meals array.
Make sure that these items are strongly typed (Data Transfer Objects / Value Objects patterns) and that Description field is marked [Bindable].
Depending on the remoting mechanism you are using you may be able to use something like makeObjectsBindable flag which replaces returned Object items with bindable ObjectProxy instances.
But I'll advise strong typing anyway.
You can get rid of it by making your dataProvider an EventDispatcher: ObjectProxy is an EventDispatcher. It will automatically wrap your data to a specified or infinite depth (default behavior).
metaPanelDataGrid.dataProvider = new ObjectProxy(meals);
It's basically the same thing as with ArrayCollection but deeper.
I have what seems to be a simple problem but one that I can't seem to find answers to. I have a class with properties. One of those properties returns a List. I have a method that cycles through all properties of any kind of class and produces a TreeNode for that class (a communication log application). When I come across the property identified as a List, I don't know how to cast the property.GetValue properly. the property.PropertyType is known but what ever I try, I get a compilation error or a runtime error.
Here is what I'm trying to do...
foreach (PropertyInfo prop in props)
{
if(prop.PropertyType.Namespace == "System.Collections.Generic")
{
List<object> oList = prop.GetValue(data, null);
MessageBox.Show(oList.Count.ToString())
}
}
If I put a breakpoint on the GetValue line, the prop parameter knows that it's a list of "myclass" items with three elements. I just can't cast it to either a list of objects (which would be fine) or cast it to a list of actual "myclass" elements which would be even better. How do I cast the return value of PropertyInfo.GetValue (an object) to its List?
First of all, it's not enough (or needed in this case at all) to check the namespace. You can check if prop.PropertyType is an instance of ICollection (you can use IsAssignableFrom). I'm suggesting ICollection because you only seem to care about the Count.
You can then cast it to an ICollection (non-generic) and run Enumerable.Cast, like:
IEnumerable<MyClass> res = ((ICollection)prop.GetValue(data,null)).Cast<MyClass>();
MessageBox.Show(res.Count().ToString());
The advantage over converting directly to List is that this will work with any collection. But if you don't need that, you can try what the other answer suggests.
did you try
prop.GetValue(data, null) as List<YourClass>;
I guess you want contravariance.
Are you trying to do so?
List<object> list = (List<Product>)object;
List<object> and List<Product> wouldn't be treated as the same type.
C# 4.0 introduced covariance and contravariance for interface and delegate generic parameters, but anyway, IList<T> doesn't have contravariance.
In my humild opinion, I believe you'll need to reconsider your object graph!
PD: Just comment out if you want guidance for that!
I want to extend the FileReference class of Flex to contain a custom property. I want to do this because AS3 doesn't let me pass arguments to functions through event listeners, which makes me feel sad, so I need this property to exist on the event target, so I can access it.
I also want to be able to cast extant FileReference objects to this class without any fuss. I have:
var fr:SmxFR = e.target as SmxFR
and I want that to work; right now it just returns null.
A blank, newly instantiated SmxFR object has the extended property in place, but all of its inherited properties and objects return Error: Error #2037: Functions called in incorrect sequence, or earlier call was unsuccessful.
This is the class I am using, SmxFR.as:
package
{
import flash.net.FileReference;
public class SmxFR extends FileReference
{
public var housenum:String = "";
public function SmxFR()
{
super();
}
}
}
Kept it as straightforward as I could, really. Can someone please help me figure this out? Thanks.
Edit:
Per request, this is the instantiation which results in the aforementioned error in all inherited objects:
var fr:SmxFR = new SmxFR();
I get living handle property from that, and all other (that is, inherited) properties throw Error #2037.
So, maybe what I want to do is going to require overriding FileReferenceList? If the original objects must be instantiated to SxmFR, that's what I'll have to do, since I'm using FRL to allow the user to select multiple files at once. Are you guys sure there is no way to fast from a FileReference to my class?
You can totally pass objects via event listeners, it's just done in a specific way. I'd learn to do it correctly, rather than trying to extend a core library which could cause you problems later if you make a small mistake.
My solution: instead of extending FileReference, extend Event and add your properties to that.
var myEvent:MyExtendedEvent = new MyExtendedEvent();
myEvent.myCustomProperty = myValue;
dispatchEvent(myEvent);
Then in your handler you just write:
function myEventHandler(e:MyExtendedEvent):void {
trace(e.myCustomProperty);
}
Much more painless to go down this road! The added benefit is that if any other Flash Developer anywhere ever looks at your code they're not going to get hit in the face with a non-standard customized FileReference. :)
When e.target is instantiate as FileReference you can't cast it to SmxFR because it's not in the line of inheritance. In the other way you can a SmxFR Object to FileRefernce.
Extending FileReferenceList is not going to be helpful. FileReferenceList.browse() method creates an array of FileReference object when user selects multiple files - that happens internally (may be in its private methods) and you cannot change that behavior and force it to create SxmFR objects instead. Use custom events as Myk suggested.
This article talks about Sound objects, but may be that's applicable to FileReference objects too. May be you cannot reuse them. Post the code where you use the SmxFr class and get the said error.
EDIT: Duplicate of Should Entity Framework Context be Put into Using Statement?
I've been tossing around this idea for some time wondering what bad could happen by not properly disposing my object context and allowing it to die with the GC. Normally, I would shun this, but there is a valid reason to do it.
We are using partial classes. In those partial classes we expose properties that access FK objects. For example, let's say I have a Customer class with a CustomerType FK object. In the class, I would expose a CustomerTypeName property that does this:
public string CustomerTypeName {
get {
if (CustomerType == null) {
CustomerTypeReference.Load()
}
return CustomerType.CustomerTypeName;
}
}
This works out very handy if the original query did not do a .Include("CustomerType").
However, if I dispose the context, the above property no longer works. So... I guess this leads to a couple of questions:
1) If I never explicitly dispose of the context, what negatives will I see, if any?
2) Is there any other way to accomplish lazy loading in the above scenario and still dispose of the context?
In my answer to 'LINQ to SQL - where does your DataContext live?' we have the page as owner of the DataContext for the life of the page, and it is the page that properly disposes of the DataContext when the page is itself disposed of.
As #Chu points out it's a little dirty, but if you're going to use what is arguably a data transfer object directly in your UI, then your UI should control the lifetime of the DataContext.
Well ObjectContext's that are left around indefinitely are fine, so long as you don't keep loading / adding lots of new objects.
Every object that is loaded or added will always be tracked by the ObjectContext until it is disposed, so if you never dispose, and you keep tracking more objects it will just get bigger and bigger.
One option you could look at doing is using some utility method to either access some well known context or create a temporary context.
The key to this is using the EntityReference.EntityKey and making sure both entities are detached.
i.e.
this.CustomerType = Utility.GetDetachedObjectByKey<Customer>(
this.CustomerTypeReference.EntityKey);
The basic implementation of GetDetachedObjectByKey is something like this:
public static T GetDetachedObjectByKey<T>(EntityKey key)
where T: EntityObject
{
using (MyContext ctx = new MyContext())
{
T t = ctx.GetObjectByKey(key) as T;
ctx.Detach(t);
return t;
}
}
This will only work if the original object target is detached too. You could experiment with where the Context used by this method comes from.
Hope this helps
Alex
Why not keep the context around for the length of your screen?