Convert Anonymous to Named Type refactoring

Anonymous types are very convenient when you need to process a result of a query locally. However, if you need to pass the result around your program or if there are several queries that return the similar name/value parts, you may probably need a named type.

In such cases, JetBrains Rider can convert the existing usage (or usages) of an anonymous type into a named type and update the usages. If necessary, JetBrains Rider will find and convert similar anonymous types in the whole solution. In the dialog that this refactoring provides, you can customize the created type — specify whether it should have auto-properties or properties with backing fields, or generate equality and formatting method overrides.

In the example below, two similar anonymous types are converted into the BookLIst class, though we only invoke the refactoring on one of them. All usages of the types found within the specified scope are modified accordingly:

            
class MyTest
{
  void Test(List<Book> books)
  {
    var bookList = from book in books select new
        {book.Author, book.Title};
  }
}

class MyNewTest
{
  void Foo(List<Book> library)
  {
    var bookCatalog = from item in library select new
        {item.Author, item.Title};
  }
}

        

            
public class BookList
{
  public string Author { get; set; }
  public string Title { get; set; }
}

class MyTest
{
  private void Test(List<Book> books)
  {
    var bookList = from book in books select new BookList
        {Author = book.Author, Title = book.Title};
  }
}

class MyNewTest
{
  private void Foo(List<Book> library)
  {
    var bookCatalog = from item in library select new BookList
        {Author = item.Author, Title = item.Title};
  }
}

        

Note that this refactoring cannot be applied if the anonymous type initializer has another anonymous initializers inside. For example:

            
var bookList = from book in books
  select new {book.Author, title = new {book.Title}};

Here you can apply this refactoring to new {book.Title} but not to new {book.Author, title = new {book.Title}}.

Convert anonymous type(s) into a named type

Place the caret at either anonymous type initializer or at the new keyword.
Do one of the following:
- Press Ctrl+Alt+Shift+T and then choose Replace Anonymous Type with Named Class.
- Choose Refactor | Replace Anonymous Type with Named Class from the main menu.
The Replace Anonymous Type with Named Class dialog will open.
Specify a name for a new class, and configure the following options:
- Scope: JetBrains Rider can find anonymous types with compatible object initializers (similar name/value parts) in the whole solution, or you can apply the refactoring to the current method only.
- Location: the new named type can be created as a nested class in the current type, or created aa an independent class in the current namespace.
- How to generate properties: JetBrains Rider can generate either read and write auto-properties, or read-only properties with backing fields in the new class.
- How to generate methods: as an option, you can choose to create stubs for Equals(), GetHashCode(), and ToString() method overrides in the new class.
- Show processed usages in 'Find Results': if this checkbox is selected, JetBrains Rider shows all anonymous types that it finds and converts in the Find window. You may want to tick this checkbox if you are converting similar anonymous types in the whole solution.
To apply the refactoring, click Next.
If no conflicts are found, JetBrains Rider performs the refactoring immediately. Otherwise, it prompts you to resolve conflicts.
Right after the refactoring has been completed, all changes that it makes anywhere, including other files, are registered as a single operation. So you can use the Undo action Ctrl+Z to roll back all these changes with a single keystroke.

If you have selected Show processed usages in 'Find Results', the new class and modified usages are shown in the Find window:

Results of converting anonymous types into a named class

Last modified: 23 September 2024