Converting anonymous types to any type – codeproject

This article describes how to handle conversions from an anonymous type to a specific type by using .NET 3.5 extensions. O o data recovery It is especially helpful when using LINQ to SQL to retrieve data in the form of lists and/or arrays. Data recovery illustrator Problem With Microsoft LINQ to SQL, you enjoy the ability of using a strong programming language and at the same time having control over your data. Database management software Data objects are represented by classes automatically created when you link your data structure to your Visual Studio project via DBML files. Instead of dividing your attention between SQL and programming, you can now write data retrieving procedures within your Visual Studio programming environment. At the same time, LINK to SQL sometimes creates some challenges. Database normalization example One of such is the Anonymous type that is returned by LINQ to SQL queries. Database virtualization When you join several database tables in one query, you have to choose how to organize the returning sequence. Data recovery machine Often enough, you have to create a sequence that returns a list or an array of Anonymous type objects. Data recovery cell phone Many programmers, myself including, think that it is not the best practice to operate with such anonymous type objects at the business and/or UI layers. Data recovery wizard free Solution The Client table has client specific information. Pokemon x database In our case, it is Name and AddressID, which obviously point to some depository with addresses info for this client, but that is not our concern now. Data recovery chicago The Order table has some text describing an order in string format and a ClientID column, which points to an ID of the client who placed the order. The Group By query returns the set of rows having ID, Name, Address ID, and Total Orders for all the clients from the Client table. R studio data recovery full version In old days, you would use ADO.NET to retrieve and work with the data. Database wiki Addressing the problem If you want to use LINQ to SQL, you would create a procedure to retrieve the sequence with the required info: public static List GetClientsWithTotalOrders() In this procedure, we join the Client and Order tables and grouped by Client, calculating how many orders the client made. Data recovery freeware The result is returned in the following format: ID, Address ID, Name, and Total Orders. Let us add a property into the Client class using the ability to create partial classes, and add any property/methods we want to the classes generated by the Visual Studio Auto Designer: public int TotalOrders { get; set; } Now, the Client class has these properties: ID, Name, AddressID, and TotalOrders.


Database clustering A list of objects with all these properties is returned by the LINQ to SQL GetClientsWithTotalOrders() procedure. But, if you try to compile the procedure, you will get the error: Error 1 Cannot convert type ‘System.Collections.Generic.List‘ Unfortunately, there is no way the compiler would recognize that the anonymous type created by the program has the same set of properties as your Client class. Icare data recovery That means that you will have to deal with the anonymous List type after you retrieve the data. Data recovery jacksonville fl How can we convert this anonymous type into the Client type? This extension allows to convert an anonymous type object into a specified type. 510 k database search If you have an object of an anonymous type and want to covert it to Client type, you need to call this extension: object obj=getSomeObjectOfAnonymoustype(); At first, it creates an empty temporary object of Client type using the Activator. Database engineer CreateInstance() procedure. Data recovery california Then, it loops through every property info of the calling object, gets its value, and re-assigns the value to the corresponding property of the newly created Client object. Moto x data recovery Finally, it returns the Client type object having all the properties populated from the calling object. The second extension I created is to transform a List of Anonymous type objects into a List of a specific type objects: public static object ToNonAnonymousList( this List list, Type t) When we call the MakeGenericType(t) function on typeof(List<>), it substitutes the type of List objects with the type T and returns a Type object representing the List of T objects. The activator creates an empty list of T objects. Database administrator GetType().GetMethod(“Add”) returns the MethodInfo object which we will use to call method Add() of the newly created list. Then, we loop through the original list, changing the original type of each element into T by calling our own extension ToType() and finally adding this item into the list of type T. Database acid The returned result is the list of type T. When I published this article, I received several comments asking why I converted the anonymous type by calling these extensions when we can just use the following syntax: .Select(o => new Client { ID = o.Key.ID, AddressID = o.Key.AddressID, If you research forums, you would noticed that many developers complain that this syntax does not work for many LINQ to SQL queries and it returns the following error: “Explicit construction of entity type ‘xxxxxxxx’ in query is not allowed” This error is due to a check added by Microsoft. Database 10g “This check was added because it was supposed to be there from the beginning and was missing. Database news Constructing entity instances manually as a projection pollutes the cache with potentially malformed objects, leading to confused programmers and lots of bug reports for us. Database key value In addition, it is ambiguous whether projected entities should be in the cache or change tracked at all. Data recovery pro review The usage pattern for entities is that they are created outside of queries and inserted into tables via the DataContext and then later retrieved via queries, never created by queries”.

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