C# - 在未调用的继承类中被覆盖的受保护方法

Question

这是一个与 C# 对象继承有关的问题，但在 受保护方法 Newtonsoft.Json.Serialization.DefaultContractResolver

的上下文中

我遵循了这篇关于如何使用映射属性使用 Newtonsoft 库进行序列化的建议。 DefaultContractResolver usage

我创建了类 AbstractContractResolver、AbstractContractResolverFromFile、CustomClassImplementedContractResolver （此处为示例目的自定义命名）

public abstract class AbstractContractResolver : DefaultContractResolver{
            protected Dictionary<string, string> PropertyMappings {get { return this.getPropertyMappings(); }}

            protected override string ResolvePropertyName(string propertyName)
            {
                string resolvedName = null;
                var resolved = this.getPropertyMappings().TryGetValue(propertyName, out resolvedName);
                return (resolved) ? propertyName : base.ResolvePropertyName(propertyName);
            }
}

public abstract class AbstractContractResolverFromFile : AbstractContractResolver{
            public AbstractContractResolverFromFile(string mapperFileName){
                if(string.IsNullOrEmpty(mapperFileName)){
                    throw new InvalidOperationException(string.Format("The abstract class {0} uses a mapper file as input to resolve and populate properties.  Please specify a valid mapper file!", this.GetType()));
                }
                this.MapperFileName = mapperFileName;
            }
            protected new virtual string ResolvePropertyName(string propertyName)
            {

                string field = propertyName;
                if(this.PropertyMappings.Any() && this.PropertyMappings.ContainsKey(propertyName)){
                    field = this.PropertyMappings[propertyName];
                }
                else{
                    field = base.ResolvePropertyName(propertyName);
                }
                return field;
            }

public class CustomClassImplementedContractResolver : AbstractContractResolverFromFile{

            public CustomClassImplementedContractResolver (string mapperFileName) :  base(mapperFileName){

            }

            protected override string ResolvePropertyName(string propertyName)
            {
                return base.ResolvePropertyName(propertyName);
            }

CustomClassImplementedContractResolver 继承 AbstractContractResolverFromFile 继承自另一个类，依此类推。

我是这样使用的：

string mapperfile = "filepath/to/file.json";
CustomClassImplementedContractResolver contractResolver = new CustomClassImplementedContractResolver(mapperfile);
// Custom implementation to store mappings (PropertyName, FieldSource) in a Dictionary<string, string>
await contractResolver.PopulatePropertyMappings();
                
// Reading JSON and deserializing
using(TextReader tr = new StreamReader(jsonfile)){
    string jsoncontent = await tr.ReadToEndAsync();
    try{
        var settings = new JsonSerializerSettings();
        // Set the ContractResolver
        settings.ContractResolver = contractResolver;
        var item = JsonConvert.DeserializeObject<CustomClass>(jsoncontent, settings);

问题 -

请查看我在上述所有这些类中的受保护函数 ResolvePropertyName 的实现，并帮助我找到问题。

我认为我错误地覆盖了 - 并且 newing 正在进一步覆盖的方法...

由于调用了不正确的ResolvePropertyName，因此无法获取（从文件中）创建的自定义映射...

• DeserializeObject执行时，代码内部调用了ResolvePropertyName，但是当前的contractResolver并没有调用被覆盖的方法，它实际上调用了第一个基址AbstractContractResolver.ResolvePropertyName。 换句话说，我在所有 4 个函数（包括 CustomClassImplementedContractResolver.ResolvePropertyName）中都设置了断点，但它只执行 AbstractContractResolver 函数。

• 奇怪的是：我使用 Visual Studio Code 并在 base.ResolvePropertyName 上按 F12 可以正确导航（正如我所期望的那样）从每个继承的函数直到 base。

Answer 1

在AbstractContractResolverFromFile改

protected new virtual string ResolvePropertyName

到

protected override string ResolvePropertyName

新的东西隐藏了继承的实现，我通常建议避免它。这是需要注意的事情，因为您可能会在代码中遇到它。