QueryUrlParams

QueryUrlParams is a C# Source Generator high-performance source generator for building query URLs from DTO objects in C#.
This library generates ToQueryUrl() extension methods for your DTO classes, at compile time, to efficiently convert your decorated DTO classes into URL query strings, avoiding reflection overhead. You control the output using a set of custom attributes.

✨ Features

• Compile-time generation of ToQueryUrl() extension methods.
• Custom attributes for fine-grained control over serialization.
• Simple, clear syntax and predictable output.
• No reflection – high performance at runtime.
• Supports:
  • Nullable types
  • Dates and booleans
  • Nested decoreted DTOs
  • Arrays and collections (e.g., List<T>, T[])
  • Enums
  • Custom objects (using ToString() method)

📋 Usage

Follow these steps to get started:

1. Mark your DTO class with the [GenerateQueryUrl] attribute
   This enables the source generator to process your class and generate the extension method. You can optionally specify parameters to customize the behavior, for example:
   • Set a Base URL for the generated method, so you don’t need to pass it explicitly every time.
   • Disable automatic conversion of property names to snake_case if you want to keep original format in lower-case. Set SnakeCaseNameConvert to false.
2. Customize properties with attributes (optional)
   • [QueryParameterIgnore] - exclude a property from query parameters
   • [QueryParameterName("customName")] - specify a custom key for a property
   • [DateTimeFormat("yyyy-MM-dd")] - format DateTime properties
   • [EnumAsString] - use Enum string representation as query parameter value (default numeric representation)
3. Call .ToQueryUrl(baseUrl) on your DTO instance
   This returns the full URL with all non-null properties serialized as query parameters with passing Base Url or without it.

🛠️ Example

using QueryUrlParams;

[GenerateQueryUrl]
public class SomeUrlParams
{
    public string? Name { get; set; }

    public int? Age { get; set; }

    [QueryParameterIgnore] // This property will be ignored
    public string? InternalToken { get; set; }

    [QueryParameterName("phone")] // Use a custom key name in the query string
    public string? PhoneNumber { get; set; }

    [DateTimeFormat("yyyy-MM-dd")] // Format DateTime to only include date
    public DateTime? StartDate { get; set; }

    public List<string>? Tags { get; set; }

    public Dictionary<string, string>? Metadata { get; set; }

    public bool? IsActive { get; set; }
}

var dto = new SomeUrlParams
        {
            Name = "Alice",
            Age = 28,
            InternalToken = "secret", // Will NOT appear in URL
            PhoneNumber = "+1234567890",
            StartDate = new DateTime(2024, 5, 22),
            Tags = new List<string> { "admin", "tester" },
            Metadata = new Dictionary<string, string>
            {
                { "ref", "email" },
                { "campaign", "spring2024" }
            },
            IsActive = true
        };

string baseUrl = "https://example.com/api";

string url = dto.ToQueryUrl(baseUrl);
// Result: https://example.com/api/?name=Alice&age=28&phone=%2B1234567890&start_date=2024-05-22&tags=admin&tags=tester&ref=email&campaign=spring2024&is_active=true

📊 Performance Benchmark

QueryUrlParams shows significant performance improvements compared to traditional reflection-based URL generation.

Method	Mean	Error	StdDev	Gen0	Allocated
GenerateQueryUrl	1.513 us	0.0300 us	0.0718 us	0.5449	2.23 KB
GenerateQueryUrlReflection	5.200 us	0.1020 us	0.1990 us	0.8672	3.57 KB

This benchmark was measured by executing 1000 URL generations per method per iteration, capturing the total time for all and then averaging. The results demonstrate that source-generated code is about 3.5x faster and allocates significantly less memory then reflection-based URL generation.

📄 License

MIT License — feel free to use and contribute!

🙋 Contributing

Contributions and feedback are welcome. Please open issues ✌️