I'm trying to create a dictionary to map an enum to a set of events with the same signature . I wrote :
public enum Events {Insert, Update, Delete};
// this part makes errors
Dictionary<Events,EventHandler<T>> EventsDic = new Dictionary<Events,EventHandler<T>>()
{
{ Events.Insert , this.ItemInserted}
};
what's wrong ?
The problem is that T has to be replaced with a type since you are declaring a variable. T must be the type of the value in the dictionary or, in your specific case, the type of the event arguments. Since you specifically say you are wanting to store events, T should probably be the good old EventArgs. Your code should look something like this:
Dictionary<Events,EventHandler<EventArgs>> EventsDic = new Dictionary<Events,EventHandler<EventArgs>>()
{
{ Events.Insert , this.ItemInserted}
};
Related
Web services cannot return an anonymous type.
If you are building a LINQ query using classes through a datacontext... you cannot construct instances of those classes in a query.
Why would I want to do this? Say I want to join three "tables" or sets of objects. I have three items with a foreign key to each other. And say the lowest, most detailed of these was represented by a class that had fields from the other two to represent the data from those. In my LINQ query I would want to return a list of the lowest, most detailed class. This is one way I have decided to "join some tables together" and return data from each of them via LINQ to SQL via a WebService. This may be bad practice. I certainly do not like adding the additional properties to the lowest level class.
Consider something like this... (please ignore the naming conventions, they are driven by internal consideration) also for some reason I need to instantiate an anonymous type for the join... I don't know why that is... if I do not do it this way I get an error...
from su in _dataContext.GetTable<StateUpdate>()
join sfs in _dataContext.GetTable<SystemFacetState>()
on new { su.lngSystemFacetState } equals new { lngSystemFacetState = sfs.lngSystemFacetState }
join sf in _dataContext.GetTable<SystemFacet>()
on new { sfs.lngSystemFacet } equals new { lngSystemFacet = sf.lngSystemFacet }
join s in _dataContext.GetTable<System>()
on new { sf.lngSystem } equals new {lngSystem = s.lngSystem}
select new
{
lngStateUpdate = su.lngStateUpdate,
strSystemFacet = sf.strSystemFacet,
strSystemFacetState = sfs.strSystemFacetState,
dtmStateUpdate = su.dtmStateUpdate,
dtmEndTime = su.dtmEndTime,
lngDuration = su.lngDuration,
strSystem = s.strSystem
}
).ToList();
Notice I have to build the anonymous type which is composed of pieces of each type. Then I have to do something like this... (convert it to a known type for transport via the web service)
result = new List<StateUpdate>(from a in qr select(new StateUpdate
{
lngStateUpdate = a.lngStateUpdate,
strSystemFacet = a.strSystemFacet,
strSystemFacetState = a.strSystemFacetState,
dtmStateUpdate = a.dtmStateUpdate,
dtmEndTime = a.dtmEndTime,
lngDuration = a.lngDuration,
strSystem = a.strSystem
}));
It is just awful. And perhaps I have created an awful mess. If I am way way off track here please guide me to the light. I feel I am missing something fundamental here when I am adding all these "unmapped" properties to the StateUpdate class.
I hope someone can see what I am doing here so I can get a better way to do it.
You can create a 'dto' class which just contains the properties you need to return and populate it instead of the anonymous object:
public class Result
{
public string lngStateUpdate
{
get;
set;
}
... // other properties
}
then use it like this:
from su in _dataContext.GetTable<StateUpdate>()
...
select new Result
{
lngStateUpdate = su.lngStateUpdate,
... // other properties
}
Nitpick note - please ditch the Hungarian notation and camel casing for properties :)
I think the answer is to create another object to serve as a DTO. This object would not be mapped to the data context and can contain fields that cross the mapped objects. This solves the problems of repetitive properties in the mapped objects, and allows for instantiation of the DTO class in the query as it is not mapped.
FYI: with respect to the problem with the join- I revisited that and I think I may have had the inner and outer components of the join switched around before.
I have a plain textfield in Tridion that can have multiple values. The itemtype is a SingleLineTextField.
In the TBB code I have the following (removed the non-essential parts):
ItemFields itemFields = new ItemFields(folder.Metadata, folder.MetadataSchema);
foreach (ItemField itemField in itemFields)
{
string itemFieldValue = string.Empty;
switch (Utilities.GetFieldType(itemField))
{
case FieldType.SingleLineTextField:
itemFieldValue = itemField.ToString();
break;
}
}
Now the result in case of two entries is just two strings with a character line break in it.
String A
String B
The method used is a generic one, which also works on other fields, so I was looking for some way to find out if a SingleLineTextField has more values in it.
You can cast the field to a SingleLineTextField type, then iterate through the Values collection, something along these lines:
SingleLineTextField field = (SingleLineTextField)itemField;
foreach(string value in field.Values)
{
// do something with value
}
// or if all you want is the count of values
int i = field.Values.Count;
Firstly, I would advise against relying on the ToString() method on objects unless it is specifically documented. In this case it works with the abstract class ItemField, but this may not always be the case.
The TOM.Net API only defines Definition and Name properties for ItemField, so you need to cast your ItemField object to something more specific.
the TextField abstract class, which SingleLineTextField inherits from, defines a ToString() method, but also Value and Values properties, which are much better suited to what you're trying to do. Looking at the documentation, we can see that Values will give us an IList<String> of the values, even if your field is not multi-valued. Perfect!
So, to answer your question, "I was looking for some way to find out if a SingleLineTextField has more values in it", you need to cast your ItemField as a TextField and check the number of Values it provides, thus:
TextField textField = (TextField)itemField;
// If you need to deal with multi-valued fields separately
if (textField.Values.Count > 1)
{
//Logic to deal with multiple values goes here
}
else
{
//Logic to deal with single valued goes here
}
// Much better... If you can deal with any number of values in a generic fashion
foreach (string value in textField.Values)
{
// Generic code goes here
}
I'm doing some Actionscript work right now and I'd like to know whether there's a way to initiate an empty object's value programatically like this:
var myObj:Object = new Object;
myObj.add("aKey","aValue");
To add a property called aKey whose value is aValue
I need to create a "Dumb" (data-only) object to use as a parameter to send via POST. So I don't know offhand how long and/or how many attributes it's gonna have.
Or something like that.
Thanks
ActionScript 3 allows you to create new Objects using an expressive Object Literal syntax similar to the one found in JavaScript:
const myObj : Object = {
aKey: "aValue",
};
trace(myObj.aKey); // "aValue"
If you want to assign properties after the object has been constructed then you can use either dot notation or square bracket notation, eg:
const myObj : Object = {}; // create an empty object.
myObj.aKey = "aValue";
myObj["anotherKey"] = "anotherValue";
If you plan on sending the data over HTTP, you may wish to consider looking at the URLVariables class which will take care of URL encoding the data for you.
In the code below, a reference type is being added. How can i do this value type?
imgList.Items.Add(imgList.Items[0]);
imgList.Items[imgIndex].Data = input; <== **This updates the 0th and the newly added element which is the issues**
Please advise
In order to avoid this issue, you need to clone imgList.Items[0] before adding it to imgList.Items. This basically involves creating a new object of the same type and populating it with data from the original.
The complexity of doing so depends on what the object is, but look at the answers to this question for some tips on cloning objects.
Edit: I forgot that .MemberwiseClone was protected.
You don't say in your code what the type of object is that you're adding to the list. If it's a class of yours, you can add a method to return a copy:
public MyType ShallowCopy()
{
return (MyType)this.MemberwiseClone();
}
and use
imgList.Items.Add(imgList.Items[0].ShallowCopy());
Or you can add a copy constructor:
public MyType(MyType original)
{
// Copy each of the properties from original
this.Data = original.Data;
}
and use
imgList.Items.Add(new MyType(imgList.Items[0]));
Does anyone have any recommendations for working with name/value pairs in Flex?
Context:
I want to create a Flex UI for updating a database table. I want the UI to contain the field name(read only) and current field value (which will be editable). Im using the WebService component to retrieve the field value and then asssigning it to an object with the field name hardcoded e.g.
private function resultHandler(event:ResultEvent):Object
{
var resultsObj:Object;
resultsObj = {
name:event.result.name as String,
This approach however is adding the dependency that the table structure/field names will never change. Using the object type also requries that i write my own algorithm to sort the output.
I'm not sure I understand the issue.
If you want to avoid dependency of the properties returned from the event at this point, simply use the event.result object, which is already an associative array.
As for sorting, we would need more context on what you are attempting to sort.
That's pretty simple. Don't use for each in loop. Use For-In Loop
Demo is shown below.
var dicEntry:Object = new Object();
dicEntry["Name"] = "Raj";
dicEntry["sal"] = 10000;
dicEntry["age"] = 33;
for(var key:Object in dicEntry)
{
trace("Object Key: "+key+" Object Value: +dicEntry[key]);
}
That's it.