Develop Reference

How to get the Id of the selectedvalue?

I have DropDownList with the following values:
ddl.SelectedValue = { Id = 234, Name = "ABC Name" }
How can I get the value of the Id?
I use WinForms and RadDropDownList

Try this one:
public int GetId(object obj)
{
var anon = new { Id = 0, Name = string.Empty };
var obj2 = MakeSameType(obj, anon);
return obj2.Id;
}
public static T MakeSameType<T>(object obj, T anonymous)
{
return (T)obj;
}
use it like:
int id = GetId(ddl.SelectedValue);
If it works, it is thanks to how the equivalent anonymous types are "condensed" in single types by the C# compiler.
Note that this solution is as brittle as you can have
If you add/remove/rename a property of the anonymous type, the GetId will break (you'll have to keep the var anon = new {...} perfectly aligned). If you move the method that creates the collection of anonymous types to another assembly it will break too (because only anonymous types inside the same assembly are "unified" by the compiler).
In general you shouldn't have anonymous types that "escape" a method. An anonymous type should remain in the method that it is defined. Assigning it directly as the DataSource of a control is asking for problems.
If you feel lazy and don't want to create a type for a key-value, use the Tuple:
var tuple = Tuple.Create(something, somethingelse, somethingstillelse);
var value1 = tuple.Item1;
var value2 = tuple.Item2;
var value3 = tuple.Item3;
and so on.

As your are using anonymous types, it gets little complicated. But, you can cast SelectedValue to dynamic, and exstract 'Id' from there:
dynamic selectedValue = ddl.SelectedValue;
int id = selectedValue.Id;
But i would recommend to declare your own class or struct for such cases.

I have changed the LINQ query
from:
var query = (from q in tableq where ...
select new {Id = q.Id, Name = q.Name});
to:
var query = (from q in tableq where ...
select q);
... and then change it to:
table1.Id = (ddl.SelectedValue as tableq).Id == null ? table1.Id : (ddl.SelectedValue as tableq).Id;

Formatting Select Statement Using Dynamic Linq

I've been looking into this for quite some time now and cannot figure out a resolution. I Originally Tried formatting A dynamic linq Statement as you can see here in this post
I declared a class:
public class DynamicHelper
{
public string FormattedLink(string DisplayText, string ID)
{
return "" + DisplayText + "";
}
public string FormattedLink(string DisplayText, int ID)
{
return "" + DisplayText + "";
}
}
After I inserted a new type in DynamicLinq into the predefinedTypes
,typeof(DynamicHelper) //around line 635
I have a program which is attempting to Invoke the FormattedLink inside of a dynamic linq select:
using (var Model = new MK3Entities())
{
DynamicHelper Dh = new DynamicHelper();
var TOrigin = (Model.Titles.Where("ID > 19632")
.Select("new(ID, #0.FormattedLink(ExtTitleID, ID) as ExtTitleID )", Dh) as System.Collections.IEnumerable)
.Cast<dynamic>().Take(10).ToList();
Console.ReadKey();
}
When I execute this program I get a runtime exception "LINQ to Entities does not recognize the method 'System.String FormattedLink(System.String, Int32)' method, and this method cannot be translated into a store expression."
Any Ideas on how to fix this... I just need simple formatting from Dynamic Select.

The error message is pretty self explanatory. The database doesn't know how to translate that method into SQL. You need to fetch the information that the method needs in your database query and then call that function on the results, rather than in the query.

I'm not sure why you need it to be dynamic, it seems the solution you present is very overly complicated. I would write it as:
using (var Model = new MK3Entities())
{
DynamicHelper Dh = new DynamicHelper();
var TOrigin = Model.Titles
.Where("ID > 19632")
.Select(t => new { ID = t.ID, ExtTitleID = t.ExtTitleId })
.Take(10)
.ToList() // Execute SQL Statement
.Select(t => new {ID = t.ID, Link = nh.FormattedLink(ExtTitleID, ID)})
.ToList();
Console.ReadKey();
}
I'm returning an List<anonymous'1> object instead of a dynamic object (because I've never had the need for dynamic objects) so you can adjust it accordingly.

I just solved similiar problem few hours back.
YOu need ToList() that works with Dynamic linq. Check out this thread: Can't find property or field on a dynamic object
Just copy paste those to your project, and later:
var TOrigin = (Model.Titles.Where("ID > 19632")
.ToAnonymousList()
.Select("new(ID, #0.FormattedLink(ExtTitleID, ID) as
ExtTitleID )", Dh) as System.Collections.IEnumerable);

How do I create a list object that contains a list of another object type using from within a query using linq and c#

I am trying to return a list of an object that contains another object list as a databmember using linq. I've tried the examples shown but I keep getting ad different error with each attempt. One of which is as follows: LINQ to Entities does not recognize the method 'System.Collections.Generic.List1[SunGard.Tools.Notifications.LinkVariable] ToList[LinkVariable](System.Collections.Generic.IEnumerable1[SunGard.Tools.Notifications.LinkVariable])' method, and this method cannot be translated into a store expression.
I have an object (AlertMessageReturn) that contains some string datamembers as well as a list aof another object (List). I have a class that defines the LinkVarible and a table that contains the values. My query looks like this:
AlertMessagesQuery = from alertMessage in this.context.AlertMessages
where alertMessage.UserId=UserId
select new AlertMessageReturn()
{ PAM_ShortMessage = alertMessage.PAM_ShortMessage,
PAM_LongMessage = alertMessage.PAM_LongMessage,
PAM_LongMessageRemote = alertMessage.PAM_LongMessageRemote,
LinkVariables = (from linkVariable in this.context.AlertMessageLinks
from user in this.context.AlertMessageUsers
where user.PAMU_PAM_ID == linkVariable.PAML_PAM_ID && user.PAMU_UserId == UserId
select new LinkVariable()
{
Name = linkVariable.PAML_SessionVariableName,
Value = linkVariable.PAML_SessionVariableValue
})
};
The error is related to the type returned for linkvariables.
Please help.
I changed the code as follows:
LinkDataQuery = from linkData in this.context.AlertMessageLinks
from user1 in this.context.AlertMessageUsers
where user1.PAMU_PAM_ID == linkData.PAML_PAM_ID && user1.PAMU_UserId == UserId
select new LinkData
{
Name = linkData.PAML_SessionVariableName,
Value = linkData.PAML_SessionVariableValue
};
var links = LinkDataQuery.ToList();
AlertMessagesQuery = from alertMessage in this.context.AlertMessages
where alertMessage.UserId=UserId
select new AlertMessageReturn()
{ PAM_ShortMessage = alertMessage.PAM_ShortMessage,
PAM_LongMessage = alertMessage.PAM_LongMessage,
PAM_LongMessageRemote = alertMessage.PAM_LongMessageRemote,
LinkVariables = links
};
var AlertMessages = AlertMessagesQuery.ToList(); // this is where the error point to
if (AlertMessages.Any())
{
return AlertMessages;
}
The error I now get is:System.NotSupportedException: Unable to create a constant value of type 'SunGard.Tools.Notifications.LinkData'. Only primitive types ('such as Int32, String, and Guid') are supported in this context.

The LINQ to SQL engine cannot turn your sub-query to generate the LinkVariables into SQL. More importantly, SQL cannot return nested data sets like that.

Any time you get a message of type 'cannot be translated into a store expression' it is an indicator that you are doing something with your linq that is attempting to be translated into other statements (usually SQL). For example, if you say
....select new MyObject
{
Id = Guid.Parse( passedIdentity ),
....
}
while this is a totally valid C# statement you will get an error that Guid.Parse cannot be handled by linq. If it is possible to move the variables into external variables that are used inside the query then it would work. So you would do...
string name = linkVariable.PAML_SessionVariableName;
string nValue = ....
....
select New LinkVariable
{
Name=name,
Value=nValue
};
Also ... you do not need the closing parens on the Select New statement.

While LINQ to SQL can bring back object heirarchies, it can't project into types that aren't part of the model. Instead of projecting into the AlertMessageReturn type, try projecting into an anonymous type in the IQueryable portion of the code. Once you're done structuring your database query, force the results to come back (using AsEnumerable) and then project that into your AlertMessageReturn type. It's more overhead, but does work. Alternatively, you can use something like AutoMapper to translate your anonymous type into the result types.
AlertMessagesQuery =
from alertMessage in this.context.AlertMessages
where alertMessage.UserId=UserId
select new
{
alertMessage.PAM_ShortMessage,
alertMessage.PAM_LongMessage,
alertMessage.PAM_LongMessageRemote,
LinkVariables = from linkVariable in this.context.AlertMessageLinks
from user in this.context.AlertMessageUsers
where user.PAMU_PAM_ID == linkVariable.PAML_PAM_ID && user.PAMU_UserId == UserId
select new
{
Name = linkVariable.PAML_SessionVariableName,
Value = linkVariable.PAML_SessionVariableValue
})
};
var alertMessageResults =
from message in AlertMessagesQuery.AsEnumerable()
select new AlertMessageResult
{
PAM_ShortMessage = mesage.PAM_ShortMessage,
PAM_LongMessage = message.PAM_LongMessage,
PAM_LongMessageRemote = message.PAM_LongMessageRemote,
LinkVariables = (from variable in message.LinkVariables
select new LinkVariable { Name=variable.Name, Value = variable.Value})
.ToList()
};
return alertMessageResults.ToList();

Dynamic LINQ: Specifying class name in new clause

With Dynamic LINQ, what changes need to be done to have fields of the given class?
For example, how can the following C# query be reproduced in DLinq:
var carsPartial = cars.Select(c => new {c.year, c.name, make = new maker() {name = c.make.name} }).ToList();
I have applied the changes mentioned in this answer https://stackoverflow.com/a/1468357/288747 to allow the return type to be the calling type rather than an anonymous type.
With the class definition is as follows (if it helps):
class car
{
public int vid;
public int odo;
public int year;
public string name;
public maker make;
}
class maker
{
public string name;
public int firstYear;
}
The following doesn't work (but I think is close, but still doesn't work as I don't have the changes necessary to the dynamic linq library, which is what I need):
var carsPartial = cars.Select("new(name, year, new maker() {name = make.name})").ToList();
But it fails at the new maker() { (as expected).
I'm sure I need to change the DynamicLibrary.cs to get this working and could do with some direction on how to alter it to achieve this.

UPDATE: I have turned my answer into a little bit more extensive blog post.
I have not really ever used Dynamic Linq library, but I have taken a look at the DynamicLibrary.cs code and the change to support generating type classes provided in another stackoverflow question you provided link to in your question. Analyzing them all, it seems that the nested new-s should work out of the box in your configuration.
However, it seems your query is not the correct Dynamic Linq's language query. Note, that the query string for DLinq is not equivalent to C# and has its own grammar.
The query should read out, I believe, the following:
var carsPartial = cars.Select("new(name, year, new maker(make.name as name) as make)").ToList();
EDIT:
Rereading this stackoverflow question more carefully, I realizes, that it actually does not extend the Dynamic Linq's language with the possibility for creating new strong-typed classes. They just put the result to the class specified as a generic parameter of Select() instead of specifying it in the query string.
To obtain what you need you will need to revert their changes (get generic DLinq) and apply my changes, I have just verified to work:
Locate the ParseNew method of ExpressionParser class and change it to the following:
Expression ParseNew() {
NextToken();
bool anonymous = true;
Type class_type = null;
if (token.id == TokenId.Identifier)
{
anonymous = false;
StringBuilder full_type_name = new StringBuilder(GetIdentifier());
NextToken();
while (token.id == TokenId.Dot)
{
NextToken();
ValidateToken(TokenId.Identifier, Res.IdentifierExpected);
full_type_name.Append(".");
full_type_name.Append(GetIdentifier());
NextToken();
}
class_type = Type.GetType(full_type_name.ToString(), false);
if (class_type == null)
throw ParseError(Res.TypeNotFound, full_type_name.ToString());
}
ValidateToken(TokenId.OpenParen, Res.OpenParenExpected);
NextToken();
List<DynamicProperty> properties = new List<DynamicProperty>();
List<Expression> expressions = new List<Expression>();
while (true) {
int exprPos = token.pos;
Expression expr = ParseExpression();
string propName;
if (TokenIdentifierIs("as")) {
NextToken();
propName = GetIdentifier();
NextToken();
}
else {
MemberExpression me = expr as MemberExpression;
if (me == null) throw ParseError(exprPos, Res.MissingAsClause);
propName = me.Member.Name;
}
expressions.Add(expr);
properties.Add(new DynamicProperty(propName, expr.Type));
if (token.id != TokenId.Comma) break;
NextToken();
}
ValidateToken(TokenId.CloseParen, Res.CloseParenOrCommaExpected);
NextToken();
Type type = anonymous ? DynamicExpression.CreateClass(properties) : class_type;
MemberBinding[] bindings = new MemberBinding[properties.Count];
for (int i = 0; i < bindings.Length; i++)
bindings[i] = Expression.Bind(type.GetProperty(properties[i].Name), expressions[i]);
return Expression.MemberInit(Expression.New(type), bindings);
}
Then, find the class Res and add the following error message:
public const string TypeNotFound = "Type {0} not found";
Et voilà, you will be able to construct queries like:
var carsPartial = cars.Select("new(name, year, (new your_namespace.maker(make.name as name)) as make)").ToList();
Make sure, you include the full type name including the whole namespace+class path.
To explain my change, it just checks if there is some identifier between new and opening parenthesis (see the added "if" at the begging). If so we parse full dot-separated class name and try to get its Type through Type.GetType instead of constructing own class in case of anonymous news.

If I've understood you correctly you want to make a plain anonymous class that contains fields from both class car and class maker. If it's the case you can just provide new names in that class, something like the following:
var carsPartial = cars.Select(c => new { year = c.year, name = c.name, make_name = c.make.name });
Or even provide names only to conflicting fields:
var carsPartial = cars.Select(c => new { c.year, c.name, make_name = c.make.name });

How do I get values from SelectedItem in ComboBox with Linq and C# 3.5

I am really missing something with anonymous types, because I can't figure out what to do with the Combobox.SelectedItem property.
Here's the code that populates the combobox, and it works just fine
var stocks = from st in brdc.tb_dStocks
join su in brdc.tb_rStockUsers on st.StockID equals su.StockID
where su.UserID == userRec.UserID
select new { st.StockID, su.StockUserID, st.Ticker };
cboStocks.ItemsSource = stocks;
cboStocks.DisplayMemberPath = "Ticker";
Then, when someone selects an item using the cboStocks combobox I need to figure out what that item is, but I have no idea how to do it. Clearly, this is a simple problem, but its confusing me greatly. cboStocks.SelectedItem is an object, and that object is of the anonymous type created by Linq, but thats all I can figure out.

Anonymous types are only really useful (and should only be used) with a method. Here you're creating the type in one method when you initialise the combo box and then try and access it in another when reading the selected item. This isn't going to work.
You need to create an actual type to assign to the combo box's ItemsSource.

Unfortunately, there's no good way to do that without reflection. Anonymous types aren't really meant to be stashed and retrieved from later in absence of some big reflection framework to check them out. They're pretty much just designed for temporary convenience in methods that are rearranging data internally.
I suggest that you make a named type with the same three fields; then it's a trivial matter to cast it and get what you want back out.

Found the following approach on this blog a while ago, try the following:
private List<T> MakeList<T>(T itemOftype)
{
List<T> newList = new List<T>();
return newList;
}
//create a fake type for anonymous type
var stockType = new {StockID = 0, StockUserId =0, Ticker = string.Empty};
var listOfStocks = MakeList(stockType);
var listOfStocksAnonymous = from st in brdc.tb_dStocks
join su in brdc.tb_rStockUsers on st.StockID equals su.StockID
where su.UserID == userRec.UserID
select new { st.StockID, su.StockUserID, st.Ticker };
listOfStocks = listOfStocksAnonymous.ToList<stockType>();
//now you have a direct access to all anonymous properties

I agree with ChrisF. You should use a concrete type here. However this workaround works if you want to try it out:
T Cast<T>(object obj, T type)
{
return (T)obj;
}
...
var myItem = Cast(cboStocks.SelectedItem, new { st.StockID = 0, su.StockUserID = 0, st.Ticker = "" });
...

So here's what I ended up doing, seems to work pretty well
private class StockInfo
{
public int StockID { get; set; }
public int StockUserID { get; set; }
public string Ticker { get; set; }
public StockInfo(int stockID, int stockUserID, string ticker)
{
StockID = stockID;
StockUserID = stockUserID;
Ticker = ticker;
}
}
BaxRunDataContext brdc = new BaxRunDataContext();
IEnumerable<StockInfo> stocks = from st in brdc.tb_dStocks
join su in brdc.tb_rStockUsers on st.StockID equals su.StockID
where su.UserID == userRec.UserID
select new StockInfo(st.StockID, su.StockUserID, st.Ticker);
cboStocks.ItemsSource = stocks;
cboStocks.DisplayMemberPath = "Ticker";