I'm getting the following error:
Inconsistent accessibility: parameter type 'RR.DAL.LINQSqlCLient.StaticReport' is less accessible than method 'RR.BLL.AuditTrail.InsertStaticReportAudit(RR.DAL.LINQSqlCLient.StaticReport, string)'
D:\My Projects\ASP Projects\Development\RapidReportTool\Working Directory\App_Code\BLL\AuditTrail.cs
This is my code:
public static void InsertStaticReportAudit(StaticReport staticReport, string filterString)
{
if (System.Web.HttpContext.Current.Session["AuditTrail"] != null)
{
AuditTrail CurrAuditTrail = (AuditTrail)System.Web.HttpContext.Current.Session["AuditTrail"];
AuditTrailReports auditTrailReport = new AuditTrailReports();
auditTrailReport.ID = AuditTrailReports.Insert(CurrAuditTrail.ID, staticReport.ID, filterString, DateTime.Now, true);
System.Web.HttpContext.Current.Session["AuditTrailReport"] = auditTrailReport;
}
}
The parameter StaticReport class:
partial class StaticReport
{
public bool BelongsToReportCategory(int reportCategoryID)
{
//If there is an entry StaticReport_ReportCategories junction table,
//then this static report belongs to the report category
RapidReportDataContext db = new RapidReportDataContext();
var query = from sr_sc in db.StaticReport_ReportCategories
where sr_sc.StaticReportID == this.ID && sr_sc.ReportCategoryID == reportCategoryID
select sr_sc;
if (query.Count() > 0)
return true;
else
return false;
}
}
Not sure why I'm getting this error. Please help. Thank you.
It is quite literal: the type StaticReport is not public.
Since it's a partial class you may have to look at both declarations, the 'main' declaration should use the public modifier.
The default access level is internal and you cannot use an internal type in the signature of a public method. It would be impossible to call.
You have a public method InsertStaticReportAudit having a parameter with type StaticReport. This type is not public. A caller outside your assembly would not be able to call the method and that is why the compiler doesn't accept it.
You have to make StaticReport public or InsertStaticReportAudit non-public.
Related
If a class has a property that is of a generic type (Like Thingus<T> below), is it possible to use a null instance of that class without specifying the type of the generically-typed property for that object?
using System;
public class Program
{
public static void Main()
{
DoThing(new Thingus<int>
{
Name = "Integer thingus",
Something = 42
});
//Is there a way to make this function work without the function on line 19?
//If thingus is null then I don't care what the Type is for Something.
//If not, does the type used in the function on line 19 matter for performance at all?
DoThing();
}
public static void DoThing(Thingus<string> thingus = null) => DoThing<string>(thingus);
public static void DoThing<T>(Thingus<T> thingus)
{
if(thingus is null)
{
Console.WriteLine("Oh look! The thingus is null!");
}
else
{
Console.WriteLine($"Thingus's Something is {thingus.Something}");
}
}
}
public class Thingus<T>
{
public string Name { get; set; }
public T Something { get; set; }
}
To see why it is probably impossible, consider this code snippet
public static void DoThing<T>(Thingus<T> thingus)
{
Console.WriteLine(typeof(T));
}
If you write DoThing(null), there is no hints that which type T you want to use, so it is impossible for the compiler to make it works because with just DoThing(null) you are providing not enough information for the compiler.
You don't need to specify the type parameter on your first call, because the compiler can infer it from the int on the type parameter in the argument. In your second method, it can't infer that, because you want to send null.
You can drop the method you want to drop, and call your generic method with some irrelevant type parameter to satisfy the compiler:
DoThing<Thingus<int>>(null);
So am trying to check that a property is derived from a base class before storing it in the backing field. However I get the following syntax error 'ClassBase' is a type, which is not valid in the given context for line value.IsSubclassOf(ClassBase) which makes no sense since ClassBase is a Type and IsSubclassOf is expecting a type.
MCV example below
using System;
namespace QuestionIsSubClassOf
{
class Program
{
static void Main(string[] args)
{
var DataStorageClass = new DataStorageClass();
var DerivedClassA = new ClassDedrivedA();
DataStorageClass.TypeOfClassBase = DerivedClassA.GetType();
}
}
public class DataStorageClass
{
private Type _typeOfClassBase;
public Type TypeOfClassBase
{
get { return _typeOfClassBase; }
set
{
if (value.IsSubclassOf(ClassBase))
{
_typeOfClassBase = value.GetType();
}
else
{
throw new ArgumentOutOfRangeException($"{nameof(TypeOfClassBase)} must be a subclass of {nameof(ClassBase)}");
}
}
}
}
public class ClassBase
{
}
public class ClassDedrivedA : ClassBase
{
}
public class ClassDedrivedB : ClassBase
{
}
}
You need to use the typeof operator in C#.
if (value.IsSubclassOf(typeof(ClassBase)))
{
_typeOfClassBase = value.GetType();
}
else
{
throw new ArgumentOutOfRangeException($"{nameof(TypeOfClassBase)} must be a subclass of {nameof(ClassBase)}");
}
The typeof operator returns a Type object which corresponds to the type it was passed as an argument. When you're working on an instance you may not necessarily know what that type is so typeof cannot be used, which is why the GetType() function exists on the object class.
EDIT:
I'd also like to check if you mean to use IsSubclassOf or whether you actually want to use IsInstanceOfType / IsAssignableFrom.
IsSubclassOf does not return true if you're comparing against the same type. Ie
typeof(Type1).IsSubclassOf(typeof(Type1)) //returns false
If you're always comparing instances against a base type then you can use IsInstanceOfType, otherwise you can use IsSubclassOf with an additional check for ==. Alternatively their's IsAssignableFrom but their may be caveats with that. I'd always advice reading the documentation - MSDN in this case.
EDIT 2021-03-14:
I know this is an old question, but with newer versions of C# you can use pattern matching syntax which is much nicer.
// `is` will match for base and derived types
if(value is ClassBase)
_typeOfClassBase = value.GetType();
else
throw new ArgumentOutOfRangeException(...);
I have the following method
public static async void CheckAndInsert<T>(T obj)
{
var data = AppDelegate.Self.InstanceLive.LoadAllAsync<T>().Result.ToList();
if (data.Count != 0)
{
var theData = data.FirstOrDefault(t => t.id == obj.id);
if (theData == null)
await StoreData(theData);
else
{
if (theData.__updatedAt != obj.__updatedAt)
await UpdateData(theData);
}
}
}
The database contains tables generated from an Azure database, so are guaranteed to always have an id.
In theory, this code should work, but on compilation, I'm getting an error that
Type T does not contain a definition for 'id' and no extension method 'id' of type 'T'
Is there a way to get this code running?
The trouble here is that with this generic method declaration T can be any type, including those that do not provide an Id member. Obviously, your code would break in this case, hence it is disallowed by the compiler.
To get around this, you need to provide generic type constraints to constrain T such that you can be sure it has an Id property.
public static async void CheckAndInsert<T>(T obj) where T:IIdentity
and have your model classes implement IIdentity which might look something like
public interface IIdentity
{
int Id{get;}
}
I Have this error but i can't identify the error (CS0542) for some reason:
member names cannot be the same as their enclosing type
Code:
class SuperTeam
{
string SuperTeamName;
public SuperTeam()
{
SuperTeamName = "";
}
public void SuperTeam (string nSuperTeamName)
{
SuperTeamName = nSuperTeamName;
}
}
The problem is here:
public void SuperTeam(string nSuperTeamName)
{
SuperTeamName = nSuperTeamName;
}
I believe you wanted to have a constructor for your class, and since constructor can't have a return type, the compiler is treating it as a method. Now the method name is same as the class name, that is why you are getting the error.
If it is a constructor then remove void (return type)
If it is a simple method then change the name to something other than SuperTeam
See Details about your Error - Compiler Error CS0542:
The members of a class or struct cannot have the same name as the
class or struct, unless the member is a constructor
AND (thanks to #Alexei Levenkov)
This error might be caused if you inadvertently put a return type on
a constructor, which in effect makes it into an ordinary method.
Your class is SuperTeam and it has a method called SuperTeam that isn't a constructor. I'm guessing that it was supposed to be a constructor, in which case, drop the void return type
public SuperTeam (string nSuperTeamName)
{
SuperTeamName = nSuperTeamName;
}
If it's actually supposed to be a method for setting SuperTeamName then change the name of the function (SetSuperTeamName would seem appropriate), or better yet change it into a property with a getter and a setter.
you have conflict the method has some name as the class constructor
try this for example
public SuperTeam()
{
SuperTeamName = "";
}
public void SuperTeamMethod (string nSuperTeamName)
{
SuperTeamName = nSuperTeamName;
}
Your constructor with the string nSuperTeamName is not supposed to have void. By having void, you made it one of the class' members.
EDIT: changed Activator, still doesn't work.
So I'm pretty (very) new to C# and I'm pretty sure this is a dupe, but I've looked through the previous questions and I still can't work out all the points.
I am trying to reduce code smell by replacing some repeated code with a map over a generic list. Specifically, I have code that looks like
var fooNode = node as IFoo;
var barNode = node as IBar;
var bazNode = node as IBaz;
...
if(fooNode != null)
return new FooThing();
if(barNode != null)
return new BarThing();
if(bazNode != null)
return new BazThing();
...
and I want to generalise it.
Here's my attempt:
var types = new Dictionary<Type, Type>
{
{typeof(IFoo), typeof(FooThing)},
{typeof(IBar), typeof(BarThing)},
...
}
foreach(var entry in types)
{
var castNode = node as entry.Key;
return Activator.CreateInstance(entry.Value);
}
Naturally, it doesn't work: The type or namespace name 'entry' could not be found (are you missing a using directive or an assembly reference?). Can you help? Is this sort of thing even possible in C#?
How about this?
foreach(var entry in types)
{
if (node != null && entry.Key.IsAssignableFrom(node.GetType()))
{
return Activator.CreateInstance(entry.Value);
}
}
The problem is that you are confusing generic type parameters with runtime types and in particular the Type class.
If you know what a type will be at compile time then you can use the generic Activator.CreateInstance<T>() method to create an instance of the underlying object - you can use things like type parameters so that this line of code doesn't need to know what the type is, for example:
T CreateObject<T>()
{
return Activator.CreateInstance<T>();
}
However this just passes the buck. In order to call this method the value of the type parameter T must be supplied somewhere - either way the compiler must be able to resolve T to a type (rather than a variable or method).
Conversely the Type class encodes type information at runtime such as its name or the assembly that a type is declared in. Activator.CreateInstance also comes with an overload that allows you to supply an instance of Type:
object CreateObject(Type type)
{
return Activator.CreateInstance(type);
}
In your case it looks like you don't know what the types will be at compile time, so you will be mostly working with the Type class - you can use typeof(MyClass) to get an instance of the the corresponding Type for a class known at runtime, and myObject.GetType() to get type information for an object at runtime.
var types = new Dictionary<Type, Type>
{
{typeof(IFoo), typeof(FooThing)},
{typeof(IBar), typeof(BarThing)},
...
}
foreach(var entry in types)
{
if(entry.Key.IsAssignableFrom(node.GetType()))
return Activator.CreateInstance(entry.Value);
}
return null;
Without understanding clearly your purpose for wanting to return different types from the same operation it will be hard to help. Maybe a little background information into the problem you are trying to solve??
I will assume that since you are attempting to return them interchangeably that fooThing, BartThing and BazThing have the same interface. So I am assuming the following:
public class FooThing : IMyOperations
{
}
public class BarThing : IMyOperations
{
}
public class BazThing : IMyOperations
{
}
You can define the relationship between the classes in another interface
public interface IMyChoice
{
public bool IsSelected { get; }
public IMyOperations GetWorker();
}
public class ChoiceFoo : IMyChoice
{
}
public class ChoiceBar : IMyChoice
{
}
public class ChoiceBaz : IMyChoice
{
}
Now you can say
foreach( var entry in choices)
{
if(entry.IsSelected)
{
return entry.GetWorker();
//Can't remember if i need to break after return..doubt it
}
}