c# - 将 netcore IConfigurationSection 绑定(bind)到动态对象

Question

在我的 appSettings.json 中，我有一个配置部分，只要它是 json 有效的，它就可以包含任何内容。它通常是一组键/值(字符串/字符串)

我想在我的代码中获取它并在 Controller 调用中返回它。

我查看了源代码 ( https://github.com/aspnet/Configuration/blob/6d9519622b5db2c5ac6bafa8bcdb25fe27914de3/src/Config.Binder/ConfigurationBinder.cs )，似乎我注定要使用现成的解决方案。

如果我将用例限制为键值对，我可以在 IConfigSection 中使用 AsEnumerable()，这很好。如果我想允许列表，那么我可能仍然可以解析 key 以查找 :Number 但是有人有办法轻松反序列化随机对象吗？或者甚至更好地获取配置部分而不对其进行反序列化。

例如

{
 "mySettings": 
 {
   "key1": "value1",
   "key2": "value2",
   "list": [ "item1", "item2", "item3" ],
   "complexObject": {
     "key": "value",
     "anything" :  [{"id": "3", "name": "John"}]
   }
 }
}

Answer 1

如果您滥用 .NET 4 动态对象，则有可能。正如您所说，您可以枚举配置中的所有键，它们都遵循相同的模式。对于您的示例，所有感兴趣的键都是:

mySettings null 
mySettings:list null 
mySettings:list:2 item3 
mySettings:list:1 item2 
mySettings:list:0 item1 
mySettings:key3 value3 
mySettings:key2 value2 
mySettings:key1 value1 
mySettings:complexObject null 
mySettings:complexObject:key value 
mySettings:complexObject:anything null 
mySettings:complexObject:anything:0 null 
mySettings:complexObject:anything:0:name John 
mySettings:complexObject:anything:0:id 3 

由此，我们可以构建一个 ExpandoObject，如下所示:

[HttpGet]
public IActionResult Get([FromServices] IConfiguration config)
{
    var result = new ExpandoObject();

    // retrieve all keys from your settings
    var configs = config.AsEnumerable().Where(_ => _.Key.StartsWith("mySettings"));
    foreach(var kvp in configs) 
    {
        var parent = result as IDictionary<string, object>;
        var path = kvp.Key.Split(':');

        // create or retrieve the hierarchy (keep last path item for later)
        var i = 0;
        for (i = 0; i < path.Length - 1; i++)
        {
            if (!parent.ContainsKey(path[i]))
            {
                parent.Add(path[i], new ExpandoObject());
            }

            parent = parent[path[i]] as IDictionary<string, object>;
        }

        if (kvp.Value == null)
            continue;

        // add the value to the parent
        // note: in case of an array, key will be an integer and will be dealt with later
        var key = path[i];
        parent.Add(key, kvp.Value);
    }

    // at this stage, all arrays are seen as dictionaries with integer keys
    ReplaceWithArray(null, null, result);

    return Ok(result);
}

private void ReplaceWithArray(ExpandoObject parent, string key, ExpandoObject input) 
{
    if (input == null)
        return;

    var dict = input as IDictionary<string, object>;
    var keys = dict.Keys.ToArray();

    // it's an array if all keys are integers
    if (keys.All(k => int.TryParse(k, out var dummy))) {
        var array = new object[keys.Length];
        foreach(var kvp in dict) {
            array[int.Parse(kvp.Key)] = kvp.Value;
            // Edit: If structure is nested deeper we need this next line 
            ReplaceWithArray(input, kvp.Key, kvp.Value as ExpandoObject);
        }

        var parentDict = parent as IDictionary<string, object>;
        parentDict.Remove(key);
        parentDict.Add(key, array);
    }
    else
    {
        foreach (var childKey in dict.Keys.ToList())
        {
            ReplaceWithArray(input, childKey, dict[childKey] as ExpandoObject);
        }
    }
}

注意:由于冒号 : 用作分隔符，因此您不能拥有包含冒号的键。

最后，因为你现在有了一个动态对象，你可以直接获取它的属性:

dynamic asDym = result;
string name = asDym.mySettings.complexObject.anything[0].name;