c# - JSON 补丁更新嵌套对象

Question

我一直在尝试使用 JSON Patch 在嵌套对象中使用替换值，但是我觉得我没有得到正确的符号。任何想法应该是什么路径？
我在 LINQPad 6 中创建了以下代码来证明它.

void Main()
{
    var patchTest = new PatchTest();
    patchTest.Create();
    patchTest.ToString().Dump("Before Patch");
    var patch = JsonConvert.DeserializeObject<JsonPatchDocument<Contact>>(
        @"[
    {
      ""op"": ""replace"",
      ""path"": ""/firstname"",
      ""value"": ""Benjamin""
    },
    {
      ""op"": ""replace"",
      ""path"": ""age"",
      ""value"": ""29""
    },
    {
      ""op"": ""replace"",
      ""path"": ""//Appointment//Name"",
      ""value"": ""fsdfdsf""
    },
]");
    patchTest.Patch(patch);
    patchTest.ToString().Dump("After Patch");
}

public class PatchTest
{
    public Contact Contact { get; set; }

    public PatchTest() { }

    public void Create()
    {
        Contact = new Contact
        {
            FirstName = "Walt",
            LastName = "Banks",
            Age = 20
        };
    }

    public void Patch(JsonPatchDocument<Contact> patch)
    {
        patch.Replace(e => e.Appointment, Contact.Appointment);
        patch.ApplyTo(Contact);
    }

    public override string ToString()
    {
        return $"{nameof(Contact)}: {Contact}";
    }
}

public class Contact
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public int Age { get; set; }
    public Appointment Appointment { get; set; }

    public override string ToString()
    {
        return $"{nameof(FirstName)}: {FirstName}, {nameof(LastName)}: {LastName}, {nameof(Appointment)}: {Appointment}";
    }
}


public class Appointment
{
    public string Name { get; set; }

    public override string ToString()
    {
        return $"{nameof(Name)}: {Name}";
    }
}

但是它找不到名称

Answer 1

找不到约会名称的原因是你没有初始化Appointment创建您的 Contact 时.更改 Create到:

public void Create()
{
    Contact = new Contact
    {
        FirstName = "Walt",
        LastName = "Banks",
        Age = 20,
        Appointment = new Appointment()
    };
}

在控制台应用程序中运行您的示例现在会产生以下输出:

Before Patch
Contact: FirstName: Walt, LastName: Banks, Age: 20, Appointment: Name:
After Patch
Contact: FirstName: Benjamin, LastName: Banks, Age: 29, Appointment: Name: fsdfdsf

我加了 Contact.Age到其 ToString()覆盖，因为它丢失了。还有，单例 /和双 //两者都在路径中工作。我猜你在试图找出问题时使用了后者。
现在，由于您已经在 J​​SON 中定义了文档，因此不需要定义另一个替换操作。您的 Patch方法可以简化为:

public void Patch(JsonPatchDocument<Contact> patch)
{
    patch.ApplyTo(Contact);
}

并且输出将与以前相同。等价于在代码中完成所有这些，无需手动创建 JSON 文档，如下所示:

public void Patch(Contact amendedContact)
{
    var patch = new JsonPatchDocument<Contact>();
    patch.Replace(e => e.FirstName, amendedContact.FirstName);
    patch.Replace(e => e.Age, amendedContact.Age);
    patch.Replace(e => e.Appointment.Name, amendedContact.Appointment.Name);
    patch.ApplyTo(Contact);
}

并像这样调用它:

var amendedContact = new Contact
{
    FirstName = "Benjamin",
    Age = 29,
    Appointment = new Appointment
    {
        Name = "fsdfdsf"
    }
};

patchTest.Patch(amendedContact);

这再次产生您想要的输出。但是您仍然必须确保初始化嵌套属性，否则您将遇到原始问题。