Return And Use An Anonymous Types?
Sep 5, 2009Assuming Anonymous Types are tailored to be used with LINQ, I'd like to use them for simply and fast data aggregation without an explicit class definition, like in this snippet[code]....
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C# - Are Anonymous Types Slower
Dec 30, 2010Are anonymous types slower than declarative types?
For example, does
Dim score as Double = CalculateScore()
run slower than
Dim score = CalculateScore()
Why use explicit typing if it's no slower?
Using Linq And Anonymous Types?
Jun 29, 2009I have a problem using linq and anonymous types in an asp.net vb.net application.When I write the code above, I have 2 errors :
- "declarations of variable with Option Strinct On requires an As clause"
- "the name 'item' is not declared"
Public Sub MyFunc(ByVal xe As System.Xml.Linq.XElement)
Dim lstitems = From it In xe.Elements Select txt = it.@Text, value = it.@Value
For Each item In lstitems
Dim s As String = item.txt
Next
End Sub
Does it mean that is not possible to use Option Strict On and Option Explicit On ?Or I make a syntax error ?Or is it just a bad configuration of my application ?
Using Reflection On Anonymous Types: LINQ To SQL
Mar 19, 2010I would like to use reflection on an anonymous type resulting from a LINQ to SQL query. I know that reflection on anonymous types works in general. The following code successfully generates a propertyinfo array with two elements:
Dim MyObject = New With {.Col1 = 1, .Col2 = "Test"}
Dim t As Type = MyObject.GetType()
Dim pilist As PropertyInfo() = t.GetProperties
[Code].....
Distinct Values In LINQ With Anonymous Types
Jul 2, 2011Supposing the referenced List below contains 2 elements:
Dim Countries = From c In List _
Select New With { .Country = c.Country, .CountryID = c.CountryID }
The code above returns
.Country=Spain .CountryID = 1
.Country=Spain .CountryID = 1
How can I get the distinct values? The Countries query should contain only
.Country=Spain .CountryID = 1
How To Persist Anonymous Types Instances Through NHibernate
Feb 12, 2010Instinctively, I would say that this is impossible, as NHibernate needs to know some mapping information on how to persist a given type. Thus, I encountered some situations in which I could use such a feature. For instance, through a named query or something like so. On the other hand, using a named query would require me to make an addition to the configuration file.
Let's suppose we have an application interacting with some underlying datastore. This datastore is configured through the NHibernate configuration file. Then, I wish to have NHibernate load only a subset of an entity properties, from another subsystem to which my application shouldn't need to interact much, so it is not worthy to define classes for this system, as I only need a fraction of this alien system's information, let's say three out of thirty-two data columns. For that matter, if I chose to load only those three columns let's say for performance concerns, I would then use an anonymous type, perform the required action onto this information, then persist it back to the datastore. Now, it wouldn't be of much interest to do so if I only had one entity to get loaded from the datastore, so let's say I have about 75,000 rows to load into my process. I then shall consider this subset option very seriously!
What strategy should you choose in such situation, if you needed to persist these changes to a subset only of this entity's properties?FYI: I am asking because I must write specific rules of usage with NHibernate, such rules that even a beginner developer would even be able to use it without knowing too much about NHibernate, but only following the rules and guidance of the technical documents I have to produce.
LINQ Returning List Of Anonymous Types
Mar 11, 2009Any best approach to what I'm trying to achieve (linq to sql, returning list of data to show in a grid/list etc etc)... Its complaining about anonymous type conversion, and from what I'm reading, thats not elegant way of doing it.
Public Function GetHistory(ByVal historyId As Integer) As List(Of ?????????)
Using dc As New myDataContext(Application.GetConnection)
Return (From t In dc.ActionTypes, a In t.MyTable Where a.HistoryID = historyId Select a.ActionOn, a.ActionBy, t.Description, a.ImpactedItem, a.ActionDescription).ToList
End Using
End Function
LINQ: Creating Objects Of Anonymous Types?
Oct 25, 2011I am in the process of learning LINQ to Objects. I am querying an array of reference elements using LINQ. In the code below, which I have marked with asteriks and PROBLEM, I am having difficulty returning any values for and I suspect its because of the multiple Select arguments.
'Program name:Querying an Array of Invoice Objects
'Created/revised:
'Project description:To demonstrate the use of LINQ to query objects
[Code].....
C# - Linq Group By With Anonymous Types Not Working As Expected?
Jul 14, 2011I was toying around with some of the linq samples that come with LINQPad. In the "C# 3.0 in a Nutshell" folder, under Chater 9 - Grouping, there is a sample query called "Grouping by Multiple Keys". It contains the following query:
from n in new[] { "Tom", "Dick", "Harry", "Mary", "Jay" }.AsQueryable()
group n by new
{
[Code].....
How To Declare Anonymous Types - Different Query Based On A Condition
Jun 29, 2009How to declare Anonymous types. I want to do a different query based on a condition.
Something like this:
If true then
Dim Myquery = From data In MyXML.Root.<hist> _
Select New With { _
.SensorID = CType(data.<sensor>(0), Integer)}
else
[CODE]...
Then I want to reference MyQuery outside of the condition. But how do I declare MyQuery outside of the if statement?
Linq Grouping With Anonymous Types And Option Strict
Apr 24, 2012I've got the below, where I'm grouping a collection by a propery, then wanting to access the properties of my group. Problem I have is with the anonymous typing. Because of option strict I have to give an explicit type but I can't work out what the type should be. The below doesn't compile because t.HeadAccountKey isn't a value (as t has a type of object). So either I need do some casting or my linq selector is wrong,
[Code]....
Use Linq To Entities To Group A Collection Without Using Anonymous Types?
Apr 24, 2012The documentation has an example about grouping on multiple properties[code]...
Is it possible to rewrite the original query to just return IEnumerable(Of CustomerRegionGroup), or do I have to use the anonymous type, and run a second query on the result of the first?
Using Anonymous Types And Assigning Values To Controls Or Attributes
Jul 26, 2010I'm trying to create a web site that users can log into and self serve their user information ie name, address etc. I've set up a SQL server DB with a couple of table holding the data and accessing those using Linq. I'm selecting specific data from my datacontext then trying to assign it to a label, ideally I want to assign the value to a class attribute so I can use the users details on multiple pages.
I've simplified the code (removing WHERE statement etc for the purposes of this question):
Using CurrentUserDataContext
As
New UserDataDataContext()
[Code].....
What's Equivalent Syntax For Anonymous Types In A LINQ Statement
Jun 29, 2010I'm trying to translate some C# LINQ code into VB.NET and am stuck on how to declare an anonymous type in VB.NET.[code]How do you translate C#'s new { ... } syntax into VB.NET?
View 2 RepliesCannot Iterate Of A Collection Of Anonymous Types Created From A LINQ Query?
Mar 17, 2010Every LINQ example I have seen for VB.NET anonymous types claims I can do something like this:
[code]...
Now when I go to iterate through the collection(see example below), I get an error that says "Name "x" is not declared. For Each x in Infos It's like VB.NET doesn't understand that Infos is a collection of anonymous types created by LINQ and wants me to declare "x" as some type. (Wouldn't this defeat the purpose of an anonymous type?) I have added the references to System.Data.Linq and System.Data.DataSetExtensions to my project. Here is what I am importing with the class:
[code]...
Return Multiple Types In A .Net Function?
Feb 17, 2012So you know how PHP internal functions usually return a boolean FALSE when a function fails, or some other data type when the function succeeds? Is this possible in VB .Net?For instance, lets say this simple code here Public Function TrySomething(ByVal Param As String) \what would go here??
[Code]...
You see I want to return a BOOLEAN false when a function fails, and a string when the function works. I've looked everywhere, and when I search for "return multiple types" all i find is Tuple.
.net - Using Child Classes Polymorphically With Differing Return Types?
Apr 10, 2012I have two Parser classes that inherit from a base class, BaseParser. I want to use either class as a parameter in another Monitor class. The Parser classes, CS600 and TCH600, both have two properties, RawDataList and SummaryDataList. The CS600 class's RawDataList returns a List(of CS600Data); the TCH600 RawDataList returns a List(of TCH600Data). The SummaryDataList returns similar classes in each Parser class. CS600Data and TCH600Data derive from a base class, BaseData.BaseParser also has RawDataList (List(of BaseData)) and SummaryDataList (List(of BaseSummaryData))The Monitor class has a private field, _thisParser which can be either of the two concrete Parsers above. I want to be able to call and use RawDataList and SummaryDataList of _thisParser within Monitor class, but when I construct the concrete Parser classes, Visual Studio notes that the RawDataList property of CS600 cannot override the RawDataList property of the BaseParser because they differ in their return types.
I thought that since CS600Data derived from BaseData (but also adds some new properties of its own) that I could use CS600Data wherever I use BaseData. What am I misunderstanding? How can I correctly construct these classes?
Public MustInherit Class BaseParser
Protected _rawDataList As List(Of RawGasData.BaseData)
Public MustOverride ReadOnly Property RawDataList() As List(Of RawGasData.BaseData)
[code]....
Asp.net - Declare Return Type Of The Function When There Are Two Possible Returned Types
Jan 25, 2010I have the following statement, I want to turn it into a Public Shared Function :
If isEmployee Then
Dim employeeInstance As New Employee
employeeInstance = GetEmployeeInstanceByUserId(userId)
[Code]....
Public Shared Function GetWorkerInstance(Byval isEmployee as Boolean) As ...(not sure what to write here)...
There two possible return Type. I'm not sure what I should declare for the function return type.
VS 2005 Function Return Types And Error Conditions
Jun 8, 2012Lets say I click a button on a form that calls a function in a data access class. This function inserts a record into a table in a database. The function returns an integer value for the record id of the newly inserted record. Now lets say the insert failed (syntax error, timeout, whatever). I can return a zero to the calling routine to indicate the failure, but not the error message. So in general, what's the most appropriate way to handle getting information back to a calling routine when the return parameter data type doesn't allow it?
View 3 RepliesReturn An (Anonymous Type With A Function) From A Function?
Mar 3, 2011Just so it's known, this question is mostly academic, even though I tried to use the concept in a real-world solution. I realize the example is contrived, but I believe the concept is valid.I want to write some fluent code like this:
[code]...
I realize that I can't force an anonymous type into a specific type (like implementing an interface or some other class), and I don't want the overhead of defining a specific class just to match my desired fluent name with the actual method name. So I was able to make the code work like this:
copy(my_first_file).to.Invoke(my_second_file)So there is no IntelliSense or type awareness there, and I have to include the Invoke in order to have the method run. How can I get more type safety and exclude the Invoke method, under these constraints: Anonymous Type returned from Method No additional classes or interfaces Preferably, I do not want to pass in another parameter to the copy() method that tells what type to return, unless copy becomes a generic method (but I think that means defining another class/interface, which I don't want to do)
Get A Compiler Warning For Functions Returning Value Types, Without Return Statement
Jul 21, 2009I've just been burned again by the fact that there is no compiler warning when you fail to return a result in a Function that returns a Value type. I wrote the function:
Public Function CompareTo(ByVal other As MessageIndex) As Integer Implements System.IComparable(Of MessageIndex).CompareTo
Me._messageIndex.CompareTo(other._messageIndex)
End Function
which performs the CompareTo Function for two integers, then throws the result away and returns 0, because I forgot to either assign a value to CompareTo, or use Return, and that isn't flagged by the compiler because it's valid VB for a Value type.
I happen never to use "FunctionName = ReturnValue" because it hides information from maintenance programmers and also because I think it's insane .
Is there any way I can get the compiler to issue a warning whenever my Functions are missing a Return, whether it's a Value type or not?
Return File Types In A Zipped File?
Mar 9, 2009how to loop through a zip file and return all the file extensions in the zipped file.
View 2 Replies.net - Linq, VB - Anonymous Type Cannot Be Converted To Anonymous Type?
Jul 9, 2009I'm a Linq noobie, maybe someone can point me in the right direction. What's wrong here? These anonymous types seem to have the same signatures.
[Code]...
C# :: Determining Object Equivalence For Value Types, Reference Types And ILists?
Nov 1, 2009I have a class with a Property called 'Value' which is of type Object.Value can be of any type, a structure, a class, an array, IList etc.My problem is with the setter and determining whether the value has changed or not.This is simple enough for value types, but reference types and lists present a problem.For a class, would you assume that the Equals method has been implemented correctly, or just assume that the value has changed every time the setter is called?If I did assume it's changed, then perhaps I should assume it for value types as well, so that the behaviour is consistent.
View 2 RepliesCompare Two Types In Dictionary Of Types .net?
Jun 23, 2012I need to compare two dictionary values if the types stored are equal, this is what i have
if gettype(Args(key)) = gettype(argtypes(key)) then
'' do something
end if
[Code]....
Value Of Type <anonymous Type> Cannot Be Converted To <anonymous Type>
Sep 24, 2011I am sure i am doing something terribly wrong, but i should better ask the experts.
At the third line i get the error Value of type <anonymous type> cannot be converted to <anonymous type>
Dim Query = (From c In Db.web Select New With {.AA = c.AA}).ToList
Dim v = New With {.Amount = 108}
Query.Add(v)
[VB 2010] Return Alert Message If SQL Query Return No Records
Dec 12, 2011I use this code to return records in a DataGridView:
[Code]....
.net - Anonymous Functions In C#?
Mar 13, 2011The following syntax is valid VB.NET code
Dim myCollection As New List(Of Stock)
myCollection.Add(New Stock(Guid.NewGuid, "Item1"))
myCollection.Add(New Stock(Guid.NewGuid, "Item2"))
[code]....
How can I accomplish the same thing in C#? I have tried...
myCollection.FindAll(bool delegate(Stock stock) {
if (blah blah) {
}
});
But it appears I have somehow structured it incorrectly as I get the following error. "Error 1 Invalid expression term 'bool'"
Anonymous Delegate From C#
Jun 28, 2010I have below code in C#:
[Code]...
Return An Object As The Return Value Through A RealProxy Transparent Proxy?
Oct 7, 2010I'm working up a system where I plan on using RealProxy objects to enable intercepting method calls against a set of objects, handling the call, and then returning appropriate results. This works just find for simple return types like strings or ints, but I can't seem to return objects from the RealProxy.Invoke method. Everything works. I get no errors, but the returned value is always NOTHING, instead of an object.
I've worked up the smallest sample code I could, and have included it below. Essentially, just call RPtest and single step through. The code creates a simple object, RPTestA, with a string field and an object valued field It then retrieves the string
[Code]...