How to use AutoBogus/Bogus to generate a constant value for a property based on its type?

Question

I'm trying to generate objects of a class whereby its value should reflect its type.

For example, if its property's type is a string, then that property's value should be "string" and if it is an integer, it should be of a max integer value. So far, this is what I have:

        var personFaker = new AutoFaker<Person>()
            .RuleFor(o => o.Id, 9223372036854775807); //Id is of type long
            .RuleFor(o => o.Name, "string")
            .RuleFor(o => o.Age, 2147483647); //Age is of type integer
        var bookFaker = new AutoFaker<Book>()
            .RuleFor(o => o.Id, 9223372036854775807); //Id is of type long
            .RuleFor(o => o.Title, "string")
            .RuleFor(o => o.Author, "string")
            .RuleFor(o => o.Pages, 2147483647) //Pages is of type integer
....

The problem with this approach is that I would have to list out a .RuleFor for every property of that class. This is tedious and inflexible.

I am wondering if there is a global configuration to specify what values should be generated in AutoFaker or Bogus based on a property's type. For example, for all properties of type string, its generated value can be configured to be set to the word "string".

Magdaleno

The "Configuration" Section in the GitHub does not help? github.com/nickdodd79/AutoBogus#configuration Why aren't you using the faker at all in RuleFor? You can do for example RuleFor( o => o.Pages, fake => fake.Random.Int() ) – Leary

^^ The GitHub Page also talks about Conventions, so you only need to explicitly configure those properties, that aren't filled by convention or differently from what you'd like. – Leary

@Leary CMIIW, but if I used Conventions, I would still need to configure every single property, right? At least, that's what I got from that page's example. My objective is to configure every property type to a certain value and have AutoBogus auto-populate the objects based on my configuration. I prefer configuring types instead of properties because there's essentially only 3 types (string, long and int) that I need to configure. – Magdaleno

Answer 1

Using just Bogus:

using Bogus;

void Main()
{
   var userFaker = new Faker<User>()
      .RuleForType(typeof(string), f => "this_is_a_string")
      .RuleForType(typeof(int), f => int.MaxValue)
      .RuleFor(u => u.Weight, f => f.Random.Double(100, 200));

   userFaker.Generate(3).Dump();
}

public class User
{
   public string Name;
   public int Age;
   public string Hobby;
   public double Weight;
}

---

You can go further and encapsulate those "default" rules by deriving from Faker<T> like so:

public class MyDefaultFaker<T> : Faker<T> where T : class
{
   public MyDefaultFaker()
   {
      this.RuleForType(typeof(string), f => "default_is_string");
      this.RuleForType(typeof(int), f => int.MaxValue);
   }
}

And your example becomes:

void Main()
{
   var userFaker = new MyDefaultFaker<User>()
      .RuleFor(u => u.Weight, f => f.Random.Double(100, 200));

   var bookFaker = new MyDefaultFaker<Book>();

   userFaker.Generate(3).Dump();
   bookFaker.Generate(3).Dump();
}

Reredos

Thanks! For anyone wondering, you can also do the same thing with AutoBogus by replacing Faker<T> with AutoFaker<T> in the example – Magdaleno