DimonSmart.BuilderGenerator by Dmitry Dorogoy

• NuGet / site data
• Details
  • Info
  • Original Readme
  • About
• How to use
  • Example (source csproj, source files)
  • Generated Files
• Useful
  • Download Example (.NET C# )
  • Share DimonSmart.BuilderGenerator
  • In the same category (Builder) - 5 other generators

NuGet / site data

Details

Info

info

Name: DimonSmart.BuilderGenerator

Generate builder classes via source generation. Simplifies object creation with Builder pattern.

Author: Dmitry Dorogoy

NuGet: https://www.nuget.org/packages/DimonSmart.BuilderGenerator/

You can find more details at https://github.com/DimonSmart/BuilderGenerator

Source: https://github.com/DimonSmart/BuilderGenerator

Original Readme

note

BuilderGenerator

BuilderGenerator is a Roslyn Source Generator that creates Builder classes at compile time. It�s especially helpful for classes with many properties, giving you a clear, explicit way to see what�s being initialized. You can even generate builders for third-party classes, and a simple hierarchy is supported, including links from child objects back to their parent. If you need something more specialized, take the generated code and adapt it to fit your own needs.

---

Installation

Install via NuGet:

dotnet add package BuilderGenerator

Or use your preferred IDE�s NuGet package manager interface.

---

How It Works

The BuilderGenerator uses two main approaches to specify which class to generate a builder for:

1. Attribute directly on the class.
2. Attribute on a �container� class where you specify TargetType in [GenerateBuilder(TargetType = typeof(YourClass))].

Below are some examples.

---

Examples

1. Simple Scenario: Attribute on the Class

In this example, we have a Person class and an Address class. We annotate them directly:

csharp
using BuilderGenerator.Runtime;

namespace BuilderGenerator.Sample
{
    public interface IPerson
    { }

    [GenerateBuilder] // Directly on the Person class
    public class Person : IPerson
    {
        public string? Name { get; set; }
        public int Age { get; set; }
        public Address? Address { get; set; }
    }

    [GenerateBuilder] // Directly on the Address class
    public class Address
    {
        public string? Street { get; set; }
        public string? City { get; set; }
        public IPerson? Person { get; set; }
    }
}

Thanks to these attributes, the Source Generator will create:

• PersonBuilder (with fluent methods Name(...), Age(...), Address(...))
• AddressBuilder (with fluent methods Street(...), City(...), Person(...))

Usage might look like:

csharp
var person = PersonBuilder.Create()
    .Name("John")
    .Age(30)
    // Here we invoke a nested Address builder
    .Address(addr => addr
        .Street("Main St.")
        .City("Metropolis")
    )
    .Build();

After building, person becomes an instance of the Person class populated with those property values.

---

2. Container Approach: Attribute on Another Class

Sometimes you might not want to mark the target class directly with [GenerateBuilder].
Instead, you can create a separate "container" class (or file) and specify which type it should generate a builder for:

csharp
using BuilderGenerator.Runtime;

namespace BuilderGenerator.OtherSamples
{
    [GenerateBuilder(TargetType = typeof(Person))]
    [GenerateBuilder(TargetType = typeof(Address))]
    public class PersonBuilderContainer
    {
        // Could be empty
    }

    // Meanwhile, Person and Address themselves have no direct attribute:
    public class Person
    {
        public string? Name { get; set; }
        public int Age { get; set; }
        public Address? Address { get; set; }
    }

    public class Address
    {
        public string? Street { get; set; }
        public string? City { get; set; }
        public IPerson? Person { get; set; }
    }
}

The generator will now produce PersonBuilderContainerBuilder.g.cs and AddressBuilderContainerBuilder.g.cs (or very similarly named files) that act as your fluent builder classes.

Usage is the same pattern:

csharp
var person = PersonBuilderContainer.Create()
    .Name("Alice")
    .Age(25)
    .Address(addr => addr
        .Street("Baker St.")
        .City("London")
    )
    .Build();

---

3. Hierarchical Builder Example

The above code already shows how you can nest calls, for example:

csharp
var person = PersonBuilder.Create()
    .Name("Bruce")
    .Age(42)
    .Address(a => a
        .Street("Gotham Rd.")
        .City("Gotham")
    )
    .Build();

When Address(...) is called, the generator automatically creates a nested builder for Address.

---

4. Setting a Reference to the Parent

In some scenarios, you may want an object to reference its �parent.� For instance, an Address might have a property Person Person { get; set; }. In your example, IPerson? Person { get; set; } is a reference back to the parent. The Source Generator includes a helper method called:

csharp
public TParent BuildAndSetParent<TProperty>(
    Expression<Func<TheChildClass, TProperty>> parentSelector
) where TProperty : class
{
    // ...
}

This method allows you to set the parent reference in the child builder. Here�s a conceptual usage snippet (the code is somewhat simplified to illustrate the idea):

csharp
var personBuilder = PersonBuilder.Create();
var addressBuilder = AddressBuilder.Create();

// Suppose you want address.Person to be the person you are building
// and want the final personBuilder to keep track of the newly built Address:

addressBuilder
    .Street("Parent Av.")
    .City("Capital City")
    .BuildAndSetParent(a => a.Person); 
    // "a => a.Person" indicates that the child Person property should refer back to the parent

---

License

0BSD License:
You�re free to use, copy, modify, distribute, and do pretty much anything else with BuilderGenerator.
See the 0BSD text for details.

---

Contributing

If you encounter bugs or have feature requests, feel free to open an issue or submit a pull request on GitHub.

About

note

Generating builder pattern code for classes

How to use

Example (source csproj, source files)

CSharp Project

This is the CSharp Project that references DimonSmart.BuilderGenerator

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net9.0</TargetFramework>
  </PropertyGroup>

      <PropertyGroup>
        <EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles>
        <CompilerGeneratedFilesOutputPath>$(BaseIntermediateOutputPath)\GX</CompilerGeneratedFilesOutputPath>
    </PropertyGroup>

      <ItemGroup>
        <PackageReference Include="DimonSmart.BuilderGenerator" Version="1.25310.2229" />
      </ItemGroup>

      
</Project>

Program.cs

This is the use of DimonSmart.BuilderGenerator in Program.cs

using Builder;

var pOld = new Person();
pOld.FirstName = "Andrei";
pOld.LastName = "Ignat";
pOld.MiddleName = "G";
var build = new PersonBuilder()
    .FirstName(pOld.FirstName)
    .MiddleName("")
    .LastName(pOld.LastName)
    ;

var pNew = build.Build();
System.Console.WriteLine(pNew.FullName());
System.Console.WriteLine(pOld.FullName());

Person.cs

This is the use of DimonSmart.BuilderGenerator in Person.cs

namespace Builder;
[DimonSmart.BuilderGenerator.Runtime.GenerateBuilder]
public class Person
{
    public string FirstName { get; set; }
    public string? MiddleName { get; set; }
    public string LastName { get; set; }

    public string FullName()
    {
        return FirstName + " " + MiddleName + " "+LastName;
    }
    
}

Generated Files

Those are taken from $(BaseIntermediateOutputPath)\GX

GenerateBuilderAttribute.g.cs

using System;
namespace DimonSmart.BuilderGenerator.Runtime
{
    [AttributeUsage(AttributeTargets.Class, Inherited = false, AllowMultiple = false)]
    public sealed class GenerateBuilderAttribute : Attribute
    {
        public Type TargetType { get; set; }
    }
}

PersonBuilder.g.cs

// <auto-generated />
using System;
using System.Reflection;
using System.Linq.Expressions;
namespace Builder
{
    public class PersonBuilder
    {
        private readonly Builder.Person _instance = new Builder.Person();
        public static PersonBuilder Create()
        {
            return new PersonBuilder();
        }
        public PersonBuilder FirstName(string value)
        {
            _instance.FirstName = value;
            return this;
        }
        public PersonBuilder MiddleName(string? value)
        {
            _instance.MiddleName = value;
            return this;
        }
        public PersonBuilder LastName(string value)
        {
            _instance.LastName = value;
            return this;
        }
        public Builder.Person Build()
        {
            return _instance;
        }
        public static implicit operator Builder.Person(PersonBuilder builder)
        {
            return builder.Build();
        }
    }
    public class PersonBuilder<TParent>
    {
        private readonly Builder.Person _instance = new Builder.Person();
        private readonly TParent _parent;
        public PersonBuilder(TParent parent)
        {
            _parent = parent;
        }
        public PersonBuilder<TParent> FirstName(string value)
        {
            _instance.FirstName = value;
            return this;
        }
        public PersonBuilder<TParent> MiddleName(string? value)
        {
            _instance.MiddleName = value;
            return this;
        }
        public PersonBuilder<TParent> LastName(string value)
        {
            _instance.LastName = value;
            return this;
        }
        public TParent BuildAndSetParent<TProperty>(Expression<Func<Builder.Person, TProperty>> parentSelector) where TProperty : class
        {
            var memberExpr = (MemberExpression)parentSelector.Body;
            var propertyInfo = memberExpr.Member as PropertyInfo;
            if (propertyInfo == null)
            {
                var interfaceType = memberExpr.Member.DeclaringType;
                propertyInfo = interfaceType.GetProperty(memberExpr.Member.Name);
            }
            propertyInfo.SetValue(_instance, _parent);
            return _parent;
        }
        public Builder.Person Build()
        {
            return _instance;
        }
    }
}

PersonBuilderBuilder.g.cs

// <auto-generated />
using System;
using System.Reflection;
using System.Linq.Expressions;
namespace Builder
{
    public class PersonBuilderBuilder
    {
        private readonly Builder.Person _instance = new Builder.Person();
        public static PersonBuilderBuilder Create()
        {
            return new PersonBuilderBuilder();
        }
        public PersonBuilderBuilder FirstName(string value)
        {
            _instance.FirstName = value;
            return this;
        }
        public PersonBuilderBuilder MiddleName(string? value)
        {
            _instance.MiddleName = value;
            return this;
        }
        public PersonBuilderBuilder LastName(string value)
        {
            _instance.LastName = value;
            return this;
        }
        public Builder.Person Build()
        {
            return _instance;
        }
        public static implicit operator Builder.Person(PersonBuilderBuilder builder)
        {
            return builder.Build();
        }
    }
    public class PersonBuilderBuilder<TParent>
    {
        private readonly Builder.Person _instance = new Builder.Person();
        private readonly TParent _parent;
        public PersonBuilderBuilder(TParent parent)
        {
            _parent = parent;
        }
        public PersonBuilderBuilder<TParent> FirstName(string value)
        {
            _instance.FirstName = value;
            return this;
        }
        public PersonBuilderBuilder<TParent> MiddleName(string? value)
        {
            _instance.MiddleName = value;
            return this;
        }
        public PersonBuilderBuilder<TParent> LastName(string value)
        {
            _instance.LastName = value;
            return this;
        }
        public TParent BuildAndSetParent<TProperty>(Expression<Func<Builder.Person, TProperty>> parentSelector) where TProperty : class
        {
            var memberExpr = (MemberExpression)parentSelector.Body;
            var propertyInfo = memberExpr.Member as PropertyInfo;
            if (propertyInfo == null)
            {
                var interfaceType = memberExpr.Member.DeclaringType;
                propertyInfo = interfaceType.GetProperty(memberExpr.Member.Name);
            }
            propertyInfo.SetValue(_instance, _parent);
            return _parent;
        }
        public Builder.Person Build()
        {
            return _instance;
        }
    }
}

PersonBuilderContainerBuilder.g.cs

// <auto-generated />
using System;
using System.Reflection;
using System.Linq.Expressions;
namespace Builder
{
    public class PersonBuilderContainerBuilder
    {
        private readonly Builder.Person _instance = new Builder.Person();
        public static PersonBuilderContainerBuilder Create()
        {
            return new PersonBuilderContainerBuilder();
        }
        public PersonBuilderContainerBuilder FirstName(string value)
        {
            _instance.FirstName = value;
            return this;
        }
        public PersonBuilderContainerBuilder MiddleName(string? value)
        {
            _instance.MiddleName = value;
            return this;
        }
        public PersonBuilderContainerBuilder LastName(string value)
        {
            _instance.LastName = value;
            return this;
        }
        public Builder.Person Build()
        {
            return _instance;
        }
        public static implicit operator Builder.Person(PersonBuilderContainerBuilder builder)
        {
            return builder.Build();
        }
    }
    public class PersonBuilderContainerBuilder<TParent>
    {
        private readonly Builder.Person _instance = new Builder.Person();
        private readonly TParent _parent;
        public PersonBuilderContainerBuilder(TParent parent)
        {
            _parent = parent;
        }
        public PersonBuilderContainerBuilder<TParent> FirstName(string value)
        {
            _instance.FirstName = value;
            return this;
        }
        public PersonBuilderContainerBuilder<TParent> MiddleName(string? value)
        {
            _instance.MiddleName = value;
            return this;
        }
        public PersonBuilderContainerBuilder<TParent> LastName(string value)
        {
            _instance.LastName = value;
            return this;
        }
        public TParent BuildAndSetParent<TProperty>(Expression<Func<Builder.Person, TProperty>> parentSelector) where TProperty : class
        {
            var memberExpr = (MemberExpression)parentSelector.Body;
            var propertyInfo = memberExpr.Member as PropertyInfo;
            if (propertyInfo == null)
            {
                var interfaceType = memberExpr.Member.DeclaringType;
                propertyInfo = interfaceType.GetProperty(memberExpr.Member.Name);
            }
            propertyInfo.SetValue(_instance, _parent);
            return _parent;
        }
        public Builder.Person Build()
        {
            return _instance;
        }
    }
}

Useful

Download Example (.NET C# )

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https://ignatandrei.github.io/RSCG_Examples/v2/docs/DimonSmart.BuilderGenerator

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