c# - 如何使用 System.Text.Json 正确反序列化具有 IReadOnlyCollection<T> 的类？

Question

我有以下类(class):

public sealed class SomeClass
{
    [JsonConstructor()]
    public SomeClass(IEnumerable<string> myItems)
    {
        InternalMyItems = new Collection<string>(myItems.ToArray());
        MyItems = new ReadOnlyCollection<string>(InternalMyItems);
    }
    
    public IReadOnlyCollection<string> MyItems { get; }
    private Collection<string> InternalMyItems { get; }
}

序列化似乎工作正常:

{
  "MyItems": [
    "A",
    "B",
    "C"
  ]
}

反序列化似乎不起作用。理想情况下，我想坚持使用 ReadOnlyCollection<T>和Collection<T>而不必更改为其他一些类型。此示例代码在尝试反序列化时引发异常:

var options = new JsonSerializerOptions()
{
    WriteIndented = true
};

var items = new[] { "A", "B", "C" };
var instance = new SomeClass(items);

var json = JsonSerializer.Serialize(instance, options);

var copy = JsonSerializer.Deserialize<SomeClass>(json, options);

InvalidOperationException: Each parameter in the deserialization constructor on type 'UserQuery+SomeClass' must bind to an object property or field on deserialization. Each parameter name must match with a property or field on the object. Fields are only considered when 'JsonSerializerOptions.IncludeFields' is enabled. The match can be case-insensitive.

---

以下是代码运行并给出错误的 .NET Fiddle 示例:https://dotnetfiddle.net/vorOLX

Answer 1

构造函数参数的类型和名称必须与类中的属性匹配。 System.Text.Json 还知道如何构造 IReadOnlyCollection<T>直接使用，所以只需使用该类型。例如，您可以简单地执行以下操作:

public sealed class SomeClass
{
    [JsonConstructor]
    public SomeClass(IReadOnlyCollection<string> myItems)
                   // ^^^^ matching type         
    {
        MyItems = myItems;
    }

    public IReadOnlyCollection<string> MyItems { get; }
}