Reflection - Call constructor with parameters

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没有蜡笔的小新
没有蜡笔的小新 2021-01-04 19:13

I read type from loaded assemblies for example:

var someType = loadedAssemblies
            .Where(a => a != null && a.FullName.StartsWith(\"MY.\"         


        
2条回答
  •  醉话见心
    2021-01-04 19:30

    Well, you can create your own Factory, and write a method, that checks constructors for the type and runs first parameterized ctor with its default values:

    public static class MyFactory
    {
        public static T MyCreateInstance()
            where T : class
        {
            return (T) MyCreateInstance(typeof (T));
        }
    
        public static object MyCreateInstance(Type type)
        {
            var parametrizedCtor = type
                .GetConstructors()
                .FirstOrDefault(c => c.GetParameters().Length > 0);
    
            return parametrizedCtor != null
                ? parametrizedCtor.Invoke
                    (parametrizedCtor.GetParameters()
                        .Select(p =>
                            p.HasDefaultValue? p.DefaultValue :
                            p.ParameterType.IsValueType && Nullable.GetUnderlyingType(p.ParameterType) == null
                                ? Activator.CreateInstance(p.ParameterType)
                                : null
                        ).ToArray()
                    )
                : Activator.CreateInstance(type);
        }
    }
    

    And then you can use this method:

    var classType = loadedAssemblies
                .Where(a => a != null && a.FullName.StartsWith("MY."))
                .SelectMany(a => a.GetTypes())
                .Distinct()
                .ToArray()[0];
    
    var curObject = MyFactory.MyCreateInstance(classType);
    
    // This will return an array of values
    
    object[] values = classType
                     .GetFields()
                     .Select(f => f.GetValue(curObject))
                     .ToArray();
    

    P.S. Here is a DotNet fiddle example.

    Update:

    The code is changed according to scenario you work with. Now we have two methods, one returns object, and another one that can convert it to type T.

    I've also updated the DotnetFiddle, please check it.

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