根据属性个名称的数组创建对象的子集

Question

我有一个 class 和一个属性名称数组，定义如下：

public class Dog {
    public string Name { get; set; }
    public string Breed { get; set; }
    public int Age { get; set; }
}

var desiredProperties = new [] {"Name", "Breed"};

我还有一个方法 returns 狗对象列表：

List<Dog> dogs = GetAllDogs();

有什么方法可以 return dogs 的子集，它只包含 desiredProperties 数组中定义的属性？最终，这个结果列表将被序列化为 JSON.

考虑到将允许用户指定属性的任意组合（假设它们都有效）作为数组中的输出，我已经为这个问题苦苦挣扎了一段时间。更多示例：

var desiredProperties = new [] {"Name", "Age"};
// Sample output, when serialized to JSON:
// [
//   { Name: "Max", Age: 5 },
//   { Name: "Spot", Age: 2 }
// ]

var desiredProperties = new [] {"Breed", "Age"};
// [
//   { Breed: "Scottish Terrier", Age: 5 },
//   { Breed: "Cairn Terrier", Age: 2 }
// ]

Answer 1

我不知道这是否是最有效的方法，但这是一种的方法：

var list = new List<Dog>();
list.Add(new Dog {Name = "Max", Breed = "Bull Terrier", Age = 5});
list.Add(new Dog {Name = "Woofie", Breed = "Collie", Age = 3});
var desiredProperties = new[] {"Name", "Breed"};
var exportDogs = new List<Dictionary<string, object>>();
foreach(var dog in list)
{
    var exportDog = new Dictionary<string, object>();
    foreach(var property in desiredProperties)
    {
        exportDog[property] = dog.GetType().GetProperty(property).GetValue(dog, null);
    }
    exportDogs.Add(exportDog);
}
var output = JsonConvert.SerializeObject(exportDogs);

输出将如下所示：

[{"Name":"Max","Breed":"Bull Terrier"},{"Name":"Woofie","Breed":"Collie"}]

但是，如果您不需要动态访问属性，那么这样做会好得多：

var output = list.Select(dog => new {dog.Name, dog.Breed});

然后序列化输出。

Answer 2

您可以编写一个函数来执行此操作。使用下面的扩展方法。

public static class Extensions
{
    public static object GetPropertyValue(this object obj, string propertyName)
    {
        return obj.GetType().GetProperty(propertyName).GetValue(obj);
    }

    public static List<Dictionary<string, object>> FilterProperties<T>(this IEnumerable<T> input, IEnumerable<string> properties)
    {
        return input.Select(x =>
        {
            var d = new Dictionary<string, object>();
            foreach (var p in properties)
            {
                d[p] = x.GetPropertyValue(p);
            }
            return d;
        }).ToList();
    }
}

试一试

var dogs = GetAllDogs();

var f1 = dogs.FilterProperties(new[]
{
    "Name", "Age"
});

var f2 = dogs.FilterProperties(new[]
{
    "Breed", "Age"
});

Console.WriteLine(JsonConvert.SerializeObject(f1));
Console.WriteLine(JsonConvert.SerializeObject(f2));

结果是

[{"Name":"Spot","Age":2},{"Name":"Max","Age":5}]
[{"Breed":"Cairn Terrier","Age":2},{"Breed":"Scottish Terrier","Age":5}]

Answer 3

类似这样的东西...未测试...

    var desiredProperties = new [] {"Name", "Breed"};
    var lst = (from asm in AppDomain.CurrentDomain.GetAssemblies()
                        from asmTyp in asm.GetTypes()
                        where typeof(dog).IsAssignableFrom(asmTyp) && desiredProperties.All(p=> PropertyExists(asmTyp, p))
                        select asmTyp).ToArray();

    private bool PropertyExists(Type dogType, string name)
    {
        bool ret=true;
        try{ dogType.GetProperty(name);}
        catch{ret=false};

        return ret;
    }

根据属性个名称的数组创建对象的子集

Create a subset of an object based off an array of property names

.net

c#

linq

reflection

根据 属性 个名称的数组创建对象的子集

Create a subset of an object based off an array of property names

.net

c#

linq

reflection

根据属性个名称的数组创建对象的子集