A blog post on how to use Fody
Switch branches/tags
Nothing to show
Clone or download
Fetching latest commit…
Cannot retrieve the latest commit at this time.
Permalink
Failed to load latest commit information.
Assets
FodySample
.gitignore
README.md

README.md

Fody- INotifyPropertyChanged the easy way

INotifyPropertyChanged is chiseled into the brain of every XAML developer. It provides amazing data binding power, but it has one drawback for me - code bloat. Take for example the code below, it's a class with 3 properties: LastName, FirstName and Age. It's a pretty simple class but there is a lot of framework code detracting away from the simplicity.

    public class PersonWithoutFody : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

        private int _age;
        private string _firstName;
        private string _lastName;

        public string LastName
        {
            get { return _lastName; }
            set
            {
                _lastName = value;
                RaisePropertyChanged();
            }
        }


        public string FirstName
        {
            get { return _firstName; }
            set
            {
                _firstName = value;
                RaisePropertyChanged();
            }
        }


        public int Age
        {
            get { return _age; }
            set
            {
                _age = value;
                RaisePropertyChanged();
            }
        }

        private void RaisePropertyChanged([CallerMemberName]string propertyName = "")
        {
            this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
    }

What I would love is a simpler version which keeps my code true to what it was originally. That is where Fody comes in. The same code with Fody looks like this:

    public class PersonWithFody : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

        public int Age { get; set; }

        public string FirstName { get; set; }

        public string LastName { get; set; }
    }

The lines of code reduces dramatically and is clean from framework code! Under the hood Fody weaves the equivalence of what you see in the original file at compile time.

Setting up Fody

Let's talk about how to set this up. There are 3 simple steps.

1.Nuget

The first step is to add the nuget package.

Nuget Fody PropertyChanged

2.FodyWeavers.xml

Next up, you'll need to create a FodyWeavers.xml file and add it to your project. This helps link the code weaving to the compiler.

<?xml version="1.0" encoding="utf-8" ?>
<Weavers>
  <PropertyChanged/>
</Weavers>

3.Add INotifyPropertyChanged

Finally, I just need to make my sure my classes implement INotifyPropertyChanged like so:

public class PersonWithFody : INotifyPropertyChanged

And that's it!

Some additional goodies!

Some of you will want to execute logic when the setter on the property is called. Fody has a neat way for you to intercept setter calls based on a naming convention. For instance, if I wanted to intercept the setter on the LastName property I would write a method like so:

OnLastNameChanged

You can even subscribe globally for a PropertyChange on a class by specifying a method like:

Global property changed

in some cases, you may not want a property to notify, in which case you can opt-out by specifying an attribute:

    [DoNotNotify]
    public string FirstName { get; set; }

Lastly, if you want one property to notify another property, you can use the attribute AlsoNotifyFor and then pass in the property name you want to notify like so:

    [AlsoNotifyFor("LastName")]
    public string FirstName { get; set; }

I hope Fody helps you become more productive. To learn more checkout https://github.com/Fody/PropertyChanged

I've created a sample for you try out: http://www.github.com/shenchauhan/Fody

Happy coding!!