How to make the minimum API bind the array in the query string

Preface

In the last article , We did 《 Give Way ASP.NET Core Supports binding arrays in query strings 》：

[HttpGet]
public string Get([FromQuery][ModelBinder(BinderType = typeof(IntArrayModelBinder))] int[] values)
{
    return string.Join(" ", values.Select(p => p.ToString()));
}

however , The same implementation , At the minimum API But it reported an error ：

that , Use minimum API Can you realize the same function ？

In depth exploration

Implement extension methods

Through the error prompt , We found the smallest API Looking for static of type TryParse Method :

No public static bool int[].TryParse(string, out int[]) method found for values.”

therefore , We try to be int[] Type creation TryParse Extension method ：

public static class IntArrayExtentions
{ 
    public static bool TryParse(this int[] obj, string value, out int[] result)
    {
        result = value.Trim('[', ']').Split(',').Select(str => int.Parse(str)).ToArray();
        return true;
    }
}

however , The test found no effect .

Through the call stack ：

We found the search static TryParse Source code for method ：

private MethodInfo? GetStaticMethodFromHierarchy(Type type, string name, Type[] parameterTypes, Func<MethodInfo, bool> validateReturnType)
{
    bool IsMatch(MethodInfo? method) => method is not null && !method.IsAbstract && validateReturnType(method);

    var methodInfo = type.GetMethod(name, BindingFlags.Public | BindingFlags.Static | BindingFlags.FlattenHierarchy, parameterTypes);

and type.GetMethod Method cannot get extension method .

It seems that the road is blocked ！

Custom type

Since the extension method doesn't work , That can only be used to define static TryParse Method's custom type ：

public class DemoDto
{
    public int[] Array { get; set; }
    public static bool TryParse(string value, out DemoDto result)
    {
        result = new DemoDto { Array = value.Trim('[', ']').Split(',').Select(str => int.Parse(str)).ToArray() };
        return true;
    }
}

app.MapGet("/",
    (DemoDto values) =>
{
    return string.Join(" ", values.Array.Select(p => p.ToString()));
});

Run again , Successful implementation :

Conclusion

For routing 、 Query and header binding source , Minimum API Static by type TryParse Method to bind custom types .

TryParse There are two API：

public static bool TryParse(string value, out T result);
public static bool TryParse(string value, IFormatProvider provider, out T result);

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