We Keep Coding

Editing an enum in a class (member cannot be accessed with an instance reference)

I'm trying to edit an enum value in a class instance based on whether that instance appears in a dictionary of type <string, myClass>. What seems logical to me is to do the code snippets below:
if (pumpDict.ContainsKey(ID))
{
foreach(KeyValuePair<string, PumpItem> kvp in pumpDict)
{
if(kvp.Key == ID)
{
kvp.Value.state = kvp.Value.state.Available; //error here
kvp.Value.fuelPumped = fuelPumped;
kvp.Value.fuelCost = fuelCost;
break;
}
}
}
else
{
PumpItem pump = new PumpItem();
pumpDict.Add(ID, pump);
}
And my PumpItems class is such:
namespace PoSClientWPF
{
public enum pumpState
{
Available,
customerWaiting,
Pumping,
customerPaying
};
public enum fuelSelection
{
Petrol,
Diesel,
LPG,
Hydrogen,
None
};
class PumpItem
{
public double fuelPumped;
public double fuelCost;
public fuelSelection selection;
public pumpState state;
public PumpItem()//intialize constructor
{
this.fuelPumped = 0;
this.fuelCost = 0;
this.selection = fuelSelection.None;
this.state = pumpState.Available;
}
}
}
I was led to believe that to have an enum value in a constructor, they have to be set up as above, with a new instance of those enums declared in the class body.
It seems to me, that what I'm trying to do is logical but I am getting an error on the right hand side of the assignation which states:
"member PoSClientWPF.pumpState.Available cannot be accessed with an instance reference; qualify is with a type name instead"
I've searched for this error among several forums but only seem to find errors involving calling static variables incorrectly. Can anyone point me in the direction of a solution?
Thanks in advance.

You are incorrectly accessing the Enum member:
// this is incorrect
kvp.Value.state = kvp.Value.state.Available; //error here
// this is the correct way
kvp.Value.state = PoSClientWPF.pumpState.Available;

You know you have a dictionary?
PumpItem pumpItem = pumpDict[ID];
pumpItem.state = PoSClientWPF.pumpState.Available;
or
PumpItem pumpItem;
if (pumpDict.TryGetValue(ID, out pumpItem))
{
pumpItem.state = PoSClientWPF.pumpState.Available;
}
else
{
pumpItem = new PumpItem();
pumpDict.Add(ID, pumpItem);
}
Could just add ID to PumpItem and use a List
PumpItem pumpItem = pumpList.FirstOrDefualt(x => x.ID == ID)
if (pumpItem == null)
pumpList.Add(new PumpItem(ID));
else
pumpItem.state = PoSClientWPF.pumpState.Available;
class PumpItem
{
public double fuelPumped = 0;
public double fuelCost = 0;
public fuelSelection selection = fuelSelection.None;
public pumpState state = pumpState.Available;
public Int32? ID = null;
public PumpItem()//intialize constructor
{ }
public PumpItem(Int32? ID)
{
this.ID = ID;
}
}

Binding Multiple MvxSpinner to a ICommand

I am creating varied number of MvxSpinners programmatically. The number of the MvxSpinners generated cannot be predetermined. It is determined by the user input.
I have a List<Beneficiary>. Each MvxSpinner is meant to update each Beneficiary in the collection.
Since I cannot determine the number of MvxSpinner (which corresponds to the count of the Beneficiary in the collection) to be generated, I am forced to have one ICommand to handle all the HandleSelectedItem event of the MvxSpinners.
The Challenge
I am having difficulty determining the index of the List<Beneficiary> to update depending on the MvxSpinner the user clicked.
An Example
let
var BeneficiaryList=new List<Beneficiary>()
If there are 5 Beneficiary object in the collection, 5 MvxSpinner will be generated.
If the user selects a MVXSpinner which is meant to update index 2 of the collection, how do i determine the index of Beneficary to update?
What I have tried
private IList<Beneficiary> _beneficiaryList;
public IList<Beneficiary> BeneficiaryList
{
get { return _beneficiaryList; }
set { _beneficiaryList= value; RaisePropertyChanged(() => BeneficiaryList); }
}
public ICommand UpdateBeneficiary=> new MvxCommand<Beneficiary>(item =>
{
//item is of type Beneficiary
//But I do not know which index of BeneficiaryList to update
});
Your help will be deeply appreciated.

You probably need a List of ICommands too, one for each spinner. Something like this in your view model...
private IList<ICommand> _commands;
public IList<ICommand> Commands {
get {
if (_commands == null) {
_commands = BeneficiaryList.Select(x => new MvxCommand<Beneficiary>(item => {
...
}));
}
return _commands;
}
}
And set up your bindings like this (assuming you've got a list of spinners)
for (int i = 0; i < spinners.Count; i++) {
var spinner = spinners[i];
set.Bind (spinner).To(vm => vm.Commands[i]);
}

Well, it is interesting to answer my own question.
What I did was to give each Spinner a unique ID that corresponds to the index of the collection.
I created a custom Spinner called MvxSpinnerIndexer extending MvxSpinner (I really do not think it matters. You can just extend Spinner). MvxSpinnerIndexer retrieved the Id and the SelectedItem and then placed the two into a Dictionary
Here is the source for MvxSpinnerIndexer
public class MvxSpinnerIndexer : Spinner
{
public MvxSpinnerIndexer(Context context, IAttributeSet attrs)
: this(
context, attrs,
new MvxAdapter(context)
{
SimpleViewLayoutId = global::Android.Resource.Layout.SimpleDropDownItem1Line
})
{ }
public MvxSpinnerIndexer(Context context, IAttributeSet attrs, IMvxAdapter adapter)
: base(context, attrs)
{
var itemTemplateId = MvxAttributeHelpers.ReadListItemTemplateId(context, attrs);
var dropDownItemTemplateId = MvxAttributeHelpers.ReadDropDownListItemTemplateId(context, attrs);
adapter.ItemTemplateId = itemTemplateId;
adapter.DropDownItemTemplateId = dropDownItemTemplateId;
Adapter = adapter;
SetupHandleItemSelected();
}
public new IMvxAdapter Adapter
{
get { return base.Adapter as IMvxAdapter; }
set
{
var existing = Adapter;
if (existing == value)
return;
if (existing != null && value != null)
{
value.ItemsSource = existing.ItemsSource;
value.ItemTemplateId = existing.ItemTemplateId;
}
base.Adapter = value;
}
}
[MvxSetToNullAfterBinding]
public IEnumerable ItemsSource
{
get { return Adapter.ItemsSource; }
set { Adapter.ItemsSource = value; }
}
public int ItemTemplateId
{
get { return Adapter.ItemTemplateId; }
set { Adapter.ItemTemplateId = value; }
}
public int DropDownItemTemplateId
{
get { return Adapter.DropDownItemTemplateId; }
set { Adapter.DropDownItemTemplateId = value; }
}
public ICommand HandleItemSelected { get; set; }
public int ViewId { get; set; }
private void SetupHandleItemSelected()
{
ItemSelected += (sender, args) =>
{
//sender.
var control = (MvxSpinnerIndexer)sender;
var controlId = control.Id;
var position = args.Position;
HandleSelected(position, controlId);
};
}
protected virtual void HandleSelected(int position, int? controlId)
{
var item = Adapter.GetRawItem(position);
var content = new Dictionary<string, object> {{"Index", controlId}, {"SelectedItem", item}};
//var param = new ListItemWithIndexModel { Index = controlId, SelectedItem = item };
if (HandleItemSelected == null
|| item == null
|| !HandleItemSelected.CanExecute(content))
return;
HandleItemSelected.Execute(content);
}
}
In your ViewModel
public ICommand SpinnerSelected => new MvxCommand<Dictionary<string, object>>(item =>
{
var selectedItem = item["SelectedItem"] as ListItemModel;//Cast to the actual model
var index = item["Index"] as int?;//The index of the collection to update
});
I believe this will be useful to the community.

Create a generic type to find implementations of in a Resharper plugin

I'm writing a plugin for resharper which I want to use to navigate from a ConcreteCommand -> ConcreteCommandHandler where those types look like this
public class ConcreteCommand : ICommand
public class ConcreteCommandHandler : ICommandHandler<ConcreteCommand>
I've got as far as adding my navigation menu option when the cursor is on a ICommand instance/definition (currently only by checking if the name contains 'Command' and not 'CommandHandler'), and I think I have the code necessary to actually search for a type which inherits something, but my issue is that the only thing I actually have a type for is my ConcereteCommand and I need to create (or get a reference to) the generic type ICommandHandler<T> with T being the type the cursor is currently on.
So I have 2 things I still want to know:
How can I check if my IDeclaredElement is an implementation of a particular interface (ideally by specifying the full name in a string from config)?
How can I create a ITypeElement which is a generic type of a specific interface where I can set the generic type from my existing IDeclaredElements type, so I can then find classes which inherit this?
My existing code looks like this:
[ContextNavigationProvider]
public class CommandHandlerNavigationProvider : INavigateFromHereProvider
{
public IEnumerable<ContextNavigation> CreateWorkflow(IDataContext dataContext)
{
ICollection<IDeclaredElement> declaredElements = dataContext.GetData(DataConstants.DECLARED_ELEMENTS);
if (declaredElements != null || declaredElements.Any())
{
IDeclaredElement declaredElement = declaredElements.First();
if (IsCommand(declaredElement))
{
var solution = dataContext.GetData(JetBrains.ProjectModel.DataContext.DataConstants.SOLUTION);
yield return new ContextNavigation("This Command's &handler", null, NavigationActionGroup.Other, () => { GotToInheritor(solution,declaredElement); });
}
}
}
private void GotToInheritor(ISolution solution, IDeclaredElement declaredElement)
{
var inheritorsConsumer = new InheritorsConsumer();
SearchDomainFactory searchDomainFactory = solution.GetComponent<SearchDomainFactory>();
//How can I create the ITypeElement MyNameSpace.ICommandHandler<(ITypeElement)declaredElement> here?
solution.GetPsiServices().Finder.FindInheritors((ITypeElement)declaredElement, searchDomainFactory.CreateSearchDomain(solution, true), inheritorsConsumer, NullProgressIndicator.Instance);
}
private bool IsCommand(IDeclaredElement declaredElement)
{
//How can I check if my declaredElement is an implementation of ICommand here?
string className = declaredElement.ShortName;
return className.Contains("Command")
&& !className.Contains("CommandHandler");
}
}

Ok managed to work this out with a fair bit of pushing in the right direction from #CitizenMatt.
basically my solution looks like this (still needs some tidying up)
private static readonly List<HandlerMapping> HandlerMappings = new List<HandlerMapping>
{
new HandlerMapping("HandlerNavigationTest.ICommand", "HandlerNavigationTest.ICommandHandler`1", "HandlerNavigationTest"),
new HandlerMapping("HandlerNavTest2.IEvent", "HandlerNavTest2.IEventHandler`1", "HandlerNavTest2")
};
public IEnumerable<ContextNavigation> CreateWorkflow(IDataContext dataContext)
{
ICollection<IDeclaredElement> declaredElements = dataContext.GetData(DataConstants.DECLARED_ELEMENTS);
if (declaredElements != null && declaredElements.Any())
{
IDeclaredElement declaredElement = declaredElements.First();
ISolution solution = dataContext.GetData(JetBrains.ProjectModel.DataContext.DataConstants.SOLUTION);
ITypeElement handlerType = GetHandlerType(declaredElement);
if (handlerType != null)
{
yield return new ContextNavigation("&Handler", null, NavigationActionGroup.Other, () => GoToInheritor(solution, declaredElement as IClass, dataContext, handlerType));
}
}
}
private static ITypeElement GetHandlerType(IDeclaredElement declaredElement)
{
var theClass = declaredElement as IClass;
if (theClass != null)
{
foreach (IPsiModule psiModule in declaredElement.GetPsiServices().Modules.GetModules())
{
foreach (var handlerMapping in HandlerMappings)
{
IDeclaredType commandInterfaceType = TypeFactory.CreateTypeByCLRName(handlerMapping.HandledType, psiModule, theClass.ResolveContext);
ITypeElement typeElement = commandInterfaceType.GetTypeElement();
if (typeElement != null)
{
if (theClass.IsDescendantOf(typeElement))
{
IDeclaredType genericType = TypeFactory.CreateTypeByCLRName(handlerMapping.HandlerType, psiModule, theClass.ResolveContext);
ITypeElement genericTypeElement = genericType.GetTypeElement();
return genericTypeElement;
}
}
}
}
}
return null;
}
private static void GoToInheritor(ISolution solution, IClass theClass, IDataContext dataContext, ITypeElement genericHandlerType)
{
var inheritorsConsumer = new InheritorsConsumer();
var searchDomainFactory = solution.GetComponent<SearchDomainFactory>();
IDeclaredType theType = TypeFactory.CreateType(theClass);
IDeclaredType commandHandlerType = TypeFactory.CreateType(genericHandlerType, theType);
ITypeElement handlerTypeelement = commandHandlerType.GetTypeElement();
solution.GetPsiServices().Finder.FindInheritors(handlerTypeelement, searchDomainFactory.CreateSearchDomain(solution, true),
inheritorsConsumer, NullProgressIndicator.Instance);
var potentialNavigationPoints = new List<INavigationPoint>();
foreach (ITypeElement inheritedInstance in inheritorsConsumer.FoundElements)
{
IDeclaredType[] baseClasses = inheritedInstance.GetAllSuperTypes();
foreach (IDeclaredType declaredType in baseClasses)
{
if (declaredType.IsInterfaceType())
{
if (declaredType.Equals(commandHandlerType))
{
var navigationPoint = new DeclaredElementNavigationPoint(inheritedInstance);
potentialNavigationPoints.Add(navigationPoint);
}
}
}
}
if (potentialNavigationPoints.Any())
{
NavigationOptions options = NavigationOptions.FromDataContext(dataContext, "Which handler do you want to navigate to?");
NavigationManager.GetInstance(solution).Navigate(potentialNavigationPoints, options);
}
}
public class InheritorsConsumer : IFindResultConsumer<ITypeElement>
{
private const int MaxInheritors = 50;
private readonly HashSet<ITypeElement> elements = new HashSet<ITypeElement>();
public IEnumerable<ITypeElement> FoundElements
{
get { return elements; }
}
public ITypeElement Build(FindResult result)
{
var inheritedElement = result as FindResultInheritedElement;
if (inheritedElement != null)
return (ITypeElement) inheritedElement.DeclaredElement;
return null;
}
public FindExecution Merge(ITypeElement data)
{
elements.Add(data);
return elements.Count < MaxInheritors ? FindExecution.Continue : FindExecution.Stop;
}
}
And this allows me no navigate to multiple handlers if they exist. This currently relies on the interfaces for the handled type and the handler type being in the same assembly. But this seems reasonable enough for me at the moment.

Find all classes which derive from a specific base class and add them to the registry

I have a base class called BaseStatus which looks like this:
public class BaseStatus
{
public int UnitId { get; protected set; }
public UInt16 StatusValue { get; protected set; }
public string StatusCode { get; protected set; }
public string StatusDescription { get; protected set; }
public BaseStatus()
{
this.UnitId = -1;
this.StatusValue = 0;
this.StatusCode = null;
this.StatusDescription = null;
}
}
Furthermore i have two or more other base classes which derive from BaseStatus and define a other unit id. For example the two classes
public class BaseGlobalStatus : BaseStatus
{
public BaseGlobalStatus()
{
base.UnitId = -1;
}
}
public class BaseGcmGdmStatus : BaseStatus
{
public BaseGcmGdmStatus()
{
base.UnitId = 2;
}
}
public class BaseCcuStatus : BaseStatus
{
public BaseCcuStatus()
{
base.UnitId = 1;
}
}
The Background is that i want to derive from for example BaseCcuStatus and have the correct UnitId in the derived class.
Now i define my correct status classes for example:
public class StatStErrDefinition : BaseGlobalStatus
{
public StatStErrDefinition()
: base()
{
base.StatusDescription = "Kommando nicht zulässig, unit im state ERROR";
base.StatusCode = "STAT_ST_ERR";
base.StatusValue = 3;
}
}
public class GcmStErrDefinition : BaseGcmGdmStatus
{
public GcmStErrDefinition()
: base()
{
base.StatusDescription = "Kommando nicht zulässig, unit im state ERROR";
base.StatusCode = "STAT_ST_ERR";
base.StatusValue = 3;
}
}
public class CcuStErrDefinition : BaseCcuStatus
{
public CcuStErrDefinition()
: base()
{
base.StatusDescription = "Kommando nicht zulässig, unit im state ERROR";
base.StatusCode = "STAT_ST_ERR";
base.StatusValue = 3;
}
}
For my understading, the three classes StatStErrDefinition, GcmStErrDefinition and CcuStErrDefinition should have the UnitId which is set in the derived BaseClass?
Now that i have defined my three Status Classes i want to get them into a registry. Currently im using this piece of code to try get them. Problem is that the result has no items.
registry = new StatusDictionary<UInt16, BaseStatus>();
var unitStatus = typeof(BaseStatus)
.Assembly.GetTypes()
.Where(x => x.BaseType == typeof(BaseStatus))
.Select(x => new
{
StatusType = x,
UnitId = x.GetProperty("UnitId", BindingFlags.Public)
StatVal = x.GetProperty("StatusValue", BindingFlags.Public)
}
)
.Where(x => x.StatVal != null && x.UnitId != null)
.Select(x => new
{
UnitId = (int)x.UnitId.GetValue(null, null),
StatusValue = (UInt16)x.StatVal.GetValue(null, null),
Factory = (Func<BaseStatus>)(() => ((BaseStatus)Activator.CreateInstance(x.StatusType)))
});
try
{
foreach (var status in unitStatus)
{
if (status.UnitId == unitId
|| status.UnitId < 0)
registry.Register(status.StatusValue, status.Factory);
}
}
catch (Exception ex)
{
string temp = ex.Message;
}
After the LINQ expression the var unitStatus is empty...
Later, the registry call looks like that to get the specific class but that is unimportant at this point:
stat = StatusContainer.GetRegistry(this.unitTypeId).GetInstance(this.StatusValue);
For information:
I want to get the status class which should be in the registry by the unittypeid and the specific status value.
Currently my registry method does not work because he is not able to find any class. So there has to be a mistake somewhere. Thanks in advance
#Update 1
I changed my functionality a little bit:
registry = new StatusDictionary<UInt16, BaseStatus>();
//get all types of cucrent assembly
var allAssemblyTypes = Assembly.GetCallingAssembly().GetTypes();
//get all types from base status
var baseStatusTypes = allAssemblyTypes.Where(x => x.BaseType == typeof(BaseStatus));
//Place all concrete types in the foundtypes
List<Type> foundTypes = new List<Type>();
foreach (Type item in baseStatusTypes)
{
var temp = allAssemblyTypes.Where(x => x.BaseType == item)
.Select(x => new
{
StatusType = x,
UnitId = x.GetProperty("UnitId", BindingFlags.Public),
StatVal = x.GetProperty("StatusValue", BindingFlags.Public),
}
);
}
Temp contains now the correct type.
Problem is that if temp is type of StatStErrDefinition the StatusValue and UnitId Property is null.
The fact is that these members are instance members. Is there a way to get the values out of them?

First thing first : your LINQ query is pretty long.
divide it in different step and store them in different variables (or make properties out of them, whatever you prefer)
This is
easy to read / maintain
easy to debug
With this given I think you are able to solve your problem :)
To check if the class is of a certain type you could use the method .OfType
Use this method to get the value. Notice that you must make an instance in your case because the value change in your constructor.
public static object GetPropValue(Type src, string propName)
{
var prop = src.GetProperty(propName);
var instance = Activator.CreateInstance(src);
var value = prop.GetValue(instance);
return value;
}
Instead of
UnitId = x.GetProperty("UnitId", BindingFlags.Public),
use
UnitId = GetPropValue(x,"UnitId"),

How can I load data in combo item property when another changed, in propertygrid c#?

I have two property in my class: MyCountry & MyCity. I set this class to sourceobject of a property grid. I want load cities i combo when select a country. for example I have 2 Country data:
Country1
Country2
And For Country1, I have (city data)
City11
City12
City13
And For Country2, I have (city data)
city21
City22
City23
When I change select country item in propertygrid, I want load cities of it in city item. this mean, when select Country1, display City11,City12,City13 in City item and when select Country2 Display City21,Cityy22,City23 in City Item.
How can I It ?
my class is :
public class KeywordProperties
{
[TypeConverter(typeof(CountryLocationConvertor))]
public string MyCountry { get; set; }
[TypeConverter(typeof(CityLocationConvertor))]
public string MyCity { get; set; }
}
and I use below class for load countries data for display in combo :
public override StandardValuesCollection GetStandardValues(ITypeDescriptorContext context)
{
HumanRoles Db = new HumanRoles();
List<LocationsFieldSet> Items = new List<LocationsFieldSet>();
Items = Db.LoadLocations(0);
string[] LocationItems = new string[Items.Count];
int count = 0;
foreach (LocationsFieldSet Item in Items)
{
LocationItems[count] = Item.Title;
count++;
}
return new StandardValuesCollection(LocationItems);
}
public override bool GetStandardValuesExclusive(ITypeDescriptorContext context)
{
return true;
}
}

The ITypeDescriptorContext interface provides a property called Instance
which lets you access the object to which the type descriptor request is connected.
You can use this property to determine the current value of the MyCountry property
the user selected. Depending on the value you can load the cities for this country.
Furthermore, in the setter of the MyCountry property I check whether or not the
new value is different from the old one and if this is the case I reset the MyCity property
(to not get an invalid combination of country and city).
Here is a small code sample. For the sake of simplicity I only use one type converter
for both properties.
public class KeywordProperties
{
public KeywordProperties()
{
MyCountry = "Country1";
}
private string myCountry;
[TypeConverter(typeof(ObjectNameConverter))]
public string MyCountry
{
get { return myCountry; }
set
{
if (value != myCountry)
MyCity = "";
myCountry = value;
}
}
private string myCity;
[TypeConverter(typeof(ObjectNameConverter))]
public string MyCity
{
get { return myCity; }
set { myCity = value; }
}
}
public class ObjectNameConverter : StringConverter
{
public override bool GetStandardValuesSupported(ITypeDescriptorContext context)
{
return true;
}
public override TypeConverter.StandardValuesCollection GetStandardValues(ITypeDescriptorContext context)
{
KeywordProperties myKeywordProps = context.Instance as KeywordProperties;
if (context.PropertyDescriptor.Name == "MyCountry")
{
List<string> listOfCountries = new List<string>();
listOfCountries.Add("Country1");
listOfCountries.Add("Country2");
return new StandardValuesCollection(listOfCountries);
}
List<string> listOfCities = new List<string>();
if (myKeywordProps.MyCountry == "Country1")
{
listOfCities.Add("City11");
listOfCities.Add("City12");
listOfCities.Add("City13");
}
else
{
listOfCities.Add("City21");
listOfCities.Add("City22");
listOfCities.Add("City23");
}
return new StandardValuesCollection(listOfCities);
}
}
In the example above there is one side effect I do not like.
Setting the MyCountry property leads to settting also the MyCity property.
To workaround this side effect you could also use the PropertyValueChanged event
of the PropertyGrid to handle invalid country/city selections.
private void propertyGrid1_PropertyValueChanged(object s, PropertyValueChangedEventArgs e)
{
if (e.ChangedItem.Label == "MyCountry")
{
if(e.ChangedItem.Value != e.OldValue)
m.MyCity = "";
}
}
If you use this event, just repalce the code in the setter of the MyCountry property with:
myCountry = value;