I would love your help. I am new to Workflow and I have define some InArguments in my workflow that I want to access in different activities. In my test project I have a InArgument named "Text" which has a default value. I am trying to access this value within my activity by doing this.
public InArgument<String> Text { get; set; }
protected override void Execute(CodeActivityContext context)
{
Console.WriteLine(string.Format("{0}.{1} Start Date Time", MethodInfo.GetCurrentMethod().DeclaringType.Name, MethodInfo.GetCurrentMethod().Name, DateTime.Now.ToString()));
Console.WriteLine(string.Format("Eric the text is: {0}", Text.Get(context)));
Console.ReadLine();
}
I have created the local InArgument with the same name as the InArgument global to the workflow. When I do the get, the value that it is returning is null. I tried to access the context object but have been unable to get to the property's value (although I saw the property's name). I apologize if this is trivial, but I would love your help.
Thank you!
The code in the activity looks fine. What for expression did you put in the Text property when you added the activity to your workflow? Because that determines the value you read, there is no default value for an InArgument that is not tied to something in the workflow.
Related
I'm working in VisualStudio on a Xamarin project.
I have a ParseObject subclass. It has a field "SentBy" that links to a ParseUser. It's constructed like this:
[ParseClassName("Beacon")]
public class Stuff_ParseBeacon : ParseObject
{
public Stuff_ParseBeacon() { }
[ParseFieldName("sentBy")]
public ParseUser SentBy
{
get { return GetProperty<ParseUser>(); }
set { SetProperty(value);}
}
}
I'm trying to include a parameter that doesn't need to be in the ParseClass on the server, which gets the data stored under "phoneNumber" from the linked user. So, like this:
public string SentByPhoneNumber
{
get
{
return SentBy.Get<string>("phoneNumber");
}
}
But I keep getting the error that there's no such key in that ParseUser--which is false, because all my ParseUsers store a phone number.
What am I doing wrong?
(BTW, in case it matters: I'm trying to use SentByPhoneNumber as a bindable property)
I don't think this is the best way to do it, but this is what I ended up doing.
I just added a phoneNumber field to the Beacon class, and it gets directly filled by the user who creates the Beacon--the user who gets stored in the SentBy field.
The problem with this is that the won't automatically update if I change the phoneNumber on the SentBy user.
This is pretty much exactly what I didn't want to do in my question.
So I'm sure there's a better way to refer to a field on a stored user than manually putting that data in the referring class at the time of creation, but it's what I've had to do to move on.
I'm making a simple Search page in MVC with some filters in it. The filters are represented by properties in my ViewModel. My ViewModel is binded to a GET form in the cshtml so my filter will appears in the querystrings and the user will be able to bookmark his search.
What I want to do is to assign a default value to some of my filters.
My (simplified) ViewModel :
public class SearchViewModel
{
//Filter I want to set a default value to
public OrganizationType? OrganizationType {get; set;}
//Results of the search
public IEnumerable<ItemViewModel> Items {get; set;}
}
I'd like to set a default value for OrganizationType. I can't simply set it in the constructor of SearchViewModel because it depends on the current user :
public void InitViewModel(SearchViewModel vm)
{
vm.OrganizationType = _someLogic.GetDefaultValue(_currentUser);
}
First solution was simply to check if OrganizationType is null, then assign a default value :
public ActionResult Search(SearchViewModel vm)
{
if(vm.OrganizationType == null)
vm.OrganizationType = _someLogic.GetDefaultValue(_currentUser);
return View(vm);
}
But this solution doesn't work as a null value corresponds to an empty filter and it's a choice that the user can make. So I can't override it.
The second solution I tried was to specify that the default value of the controller should be null in the Search action :
public ActionResult Search(SearchViewModel vm = null)
{
if (vm == null)
{
vm = new SearchViewModel();
InitViewModel(vm);
}
...
return View(vm);
}
But in practice, the variable vm is never null, so the default values are never setted.
I also tried having two Action, one wihout a ViewModel where I instanciate a new ViewModel with the default values and then call the second action :
public ActionResult Search()
{
var vm = new SearchViewModel();
InitViewModel(vm);
//Simply call the second action with the initizalied ViewModel
return Search(vm);
}
public ActionResult Search(SearchViewModel vm)
{
...
return View(vm);
}
But it doesn't work because there is now an ambiguity between the two action, and asp.net doesn't know which one to choose.
So in summary, I'd like to find a way to set a default value for a ViewModel, without setting it in the constructor and overriding user choices.
Another way to say it, how can I distinguish an "empty" ViewModel from one where some values are binded from the form.
Any idea ?
Ok I think I found a solution to my own problem...
I can use the ModelState property of the controler to check it the ViewModel is empty or was binded from the form :
public ActionResult Search(SearchViewModel vm = null)
{
if (ModelState.Count == 0)
{
InitViewModel(vm);
}
...
return View(vm);
}
So if ModelState.Count equals to 0 it means that user didn't change any filters. So the form is empty and we can bind our default values. As soon as the user will change one of the filters or submit the request, the ModelState.Count will be greater than 0 so we shouldn't set the default value. Otherwise we would override an user choice.
The logic of what you're doing is a little iffy. Generally speaking, if a value is nullable then null is the default value. However, it seems that you're trying to make a distinction here between whether the value is null because it's not set or null because the user explicitly set it to null. This type of semantic variance is usually a bad idea. If null has a meaning, then it should always carry that meaning. Otherwise, your code becomes more confusing and bugs are generally introduced as a result.
That said, you can't count on ModelState having no items. I've honestly never played around with ModelState enough in scenarios where there's not post data, but it's possible there's some scenario where there's no post data and yet ModelState may have items. Even if there isn't, this is an implementation detail. What if Microsoft does an update that adds items to ModelState in situations where it previously had none. Then, your code breaks with no obvious reason why.
The only thing you can really count on here is whether the request method is GET or POST. In the GET version of your action, you can reasonably assume that the user has made no modifications. Therefore, in this scenario, you can simply set the value to whatever you like without concern.
In the POST version of your action, the user has made some sort of modification. However, at this point, there is no way to distinguish any more whether the value is null because it is or because the user explicitly wanted it to be. Therefore, you must respect the value as-is.
I have a ICollection of Projects in my user class
public ICollection<Project> Projects { get; set; }
When I try to render the count of projects in my view, it gives an error
<h2>You have #Model.Projects.Count() projects....</h2>
Any help appreciated.
ICollection doesn't have a Count method, it has a Count property. You are probably getting confused with the LINQ Count extension method which is supported on an IEnumerable interface.
Just remove the parenthesis at the end of the Count call i.e.
<h2>You have #Model.Projects.Count projects...</h2>
I think I figured out what the issue was here. I added a constructor in my user class to handle the null reference exception
public User()
{
this.Roles = new List<Role>();
this.Projects = new List<Project>();
}
This did the trick.
And ofcourse I called count without the paranthesis
In general, I've found it useful to write default constructors of every type, so that when stepping through a project like this I can visually see when each one is called. Not having a copy constructor or something similar can mask odd issues like this and make debugging infinitely frustrating.
I want to pass a object to workflow as input parameter, without creating instance of it, as this object is already filled up with lot of sub-objects, and I want to run lot of rules on that object. I want to use
WorkflowInvoker.Invoker(this); Is this possible in Windows Workflow Foundation 4.0, If so, what should I keep in InArguments as the type?
Thanks In Advance,
Thanks for your input....
Sorry, I think I haven't kept the question correctly, I had a business class used by bank customers, class is like this,
public partial class BankName.DTOS.clsCardDetails : BaseClass
{
public string _mBankStatusCode;
protected override string IsCreditCard(HttpContext ctx)
{
Status = ctx.Request.Form["Trans_Status"];
_mBankStatusCode = Status.ToString();
}
}
Now, I have to pass this class object to workflow foundation, I should not create new instance of this class in workflow again. Because in workflow, I want to get the status, so ideally what I thought of passing to workflow is object of "BankName.DTOS.clsCardDetails". That is my question.
InArguments<> to workflow is object of BankName.DTOS.clsCardDetails
Arguments passed into a workflow need to be put into a dictionary and the dictionary is passed into the workflow.
var dictionary = new Dictionary<string, object> { { "BankName", _bankNameObject } };
WorkflowInvoker.Invoke(this, dictionary);
The key must have the same name as your InArgument and your object must have the same type as your InArgument.
You can pass as many arguments as you like into the workflow via the dictionary.
See http://blogs.msdn.com/b/rjacobs/archive/2011/05/26/passing-arguments-to-workflow-activities-again.aspx
I am very confused with properties in asp.net.
I just don't understand why we use properties and when I should use them. Could anybody elaborate a little on this.
public class Customer
{
private int m_id = -1;
public int ID
{
set
{
m_id = value;
}
}
private string m_name = string.Empty;
public string Name
{
set
{
m_name = value;
}
}
public void DisplayCustomerData()
{
Console.WriteLine("ID: {0}, Name: {1}", m_id, m_name);
}
}
Properties provide the opportunity to protect a field in a class by reading and writing to it through the property. In other languages, this is often accomplished by programs implementing specialized getter and setter methods. C# properties enable this type of protection while also letting you access the property just like it was a field.
Another benefit of properties over fields is that you can change their internal implementation over time. With a public field, the underlying data type must always be the same because calling code depends on the field being the same. However, with a property, you can change the implementation. For example, if a customer has an ID that is originally stored as an int, you might have a requirements change that made you perform a validation to ensure that calling code could never set the ID to a negative value. If it was a field, you would never be able to do this, but a property allows you to make such a change without breaking code. Now, lets see how to use properties.
Taken From CSharp-Station
There are a couple of good reasons for it. The first is that you might need to add validation logic in your setter, or actually calculate the value in the getter.
Another reason is something to do with the IL code generated. If you are working on a large project that is spread over multiple assemblies then you can change the code behind your property without the application that uses your assembly having to recompile. This is because the "access point" of the property stays the same while allowing the implementation code behind it to be altered. I first read about this when I was looking into the point of automatic properties as I didnt see the point between those and a normal public variable.
It's easy.
All fields in class MUST be private (or protected). To show fields to another class yyou can use properties or get/set methods. Properties a shorter.
P.S. Don't declare write-only properties. It is worst practices.
Properties are a convenient way to encapsulate your classes' data.
Quoting from MSDN:
A property is a member that provides a flexible mechanism to read,
write, or compute the value of a private field. Properties can be used
as if they are public data members, but they are actually special
methods called accessors. This enables data to be accessed easily and
still helps promote the safety and flexibility of methods.
Let's consider two common scenarios:
1) You want to expose the Name property without making it changeable from outside the class:
private string m_name = string.Empty;
public string Name
{
get
{
return m_name;
}
}
2) You want to perform some checks, or run some code every time the data is accessed or set:
private string m_name = string.Empty;
public string Name
{
get
{
return m_name;
}
set
{
m_name = (String.IsNullOrEmpty(value)) ? "DefaultName" : value;
}
}
see:
http://msdn.microsoft.com/en-us/library/x9fsa0sw.aspx
The most important reason is for validation purpose in setter and manipulation part can be implemented in get part.
For Ex.
Storing weekdays, which should be from 1-7, if we take normal variable and declare it as public, anyone can assign any value.
But in Properties setter you can control and validate.
The next one you can use it for tracking. That means, you can know how many times set and get functions has been called by clients (statistical purpose, may be not useful frequently).
Finally, you can control read only, write only and read/write for the properties according to your requirements.