C# 使用JSON补丁向字典添加值 概述
我正在尝试使用ASP.NET内核编写一个web服务,它允许客户端查询和修改微控制器的状态。该微控制器包含许多我在应用程序中建模的系统-例如,PWM系统、执行器输入系统等 这些系统的组件都具有特定的属性,可以使用请求查询或修改这些属性。例如,可以使用带有C# 使用JSON补丁向字典添加值 概述,c#,json-patch,C#,Json Patch,我正在尝试使用ASP.NET内核编写一个web服务,它允许客户端查询和修改微控制器的状态。该微控制器包含许多我在应用程序中建模的系统-例如,PWM系统、执行器输入系统等 这些系统的组件都具有特定的属性,可以使用请求查询或修改这些属性。例如,可以使用带有{“op”:“replace”,“path”:/pwms/3/enabled”,“value”:true}的HTTP请求启用micro上的第四个PWM。为了支持这一点,我使用了图书馆 我的问题是我正在尝试为一个新的“CAN数据库”系统实现JSON补
{“op”:“replace”,“path”:/pwms/3/enabled”,“value”:true}
的HTTP请求启用micro上的第四个PWM。为了支持这一点,我使用了图书馆
我的问题是我正在尝试为一个新的“CAN数据库”系统实现JSON补丁支持,该系统在逻辑上应该将定义名称映射到特定的CAN消息定义,我不确定如何实现这一点
细节
下图为CAN数据库系统建模。CanDatabase
实例在逻辑上应该包含一个形式为IDictionary
的字典
为了支持创建新的消息定义,我的应用程序应该允许用户发送JSON补丁请求,如下所示:
{
“op”:“添加”,
“路径”:“/candb/my\u新定义”,
“价值”:{
“模板”:[“…”,“…”],
“重复率”:“…”,
"...": "...",
}
}
在这里,my\u new\u definition
将定义名称,与值
关联的对象应反序列化为CanMessageDefinition
对象。然后应将其作为新的键值对存储在CanDatabase
字典中
问题是路径
应该指定一个属性路径,对于静态类型的对象,该路径应该是静态的(例外情况是,它允许引用数组元素,例如上面提到的/pwms/3
)
我试过的
A.利罗伊·詹金斯方法
忘记我知道它不起作用的事实——我尝试了下面的实现(尽管我需要支持动态JSON补丁路径,但它只使用静态类型),只是为了看看会发生什么
实施
内部密封类CanDatabaseModel:DeviceComponentModel
{
公共CanDatabaseModel()
{
this.Definitions=新字典();
}
[JsonProperty(PropertyName=“candb”)]
公共IDictionary定义{get;}
...
}
测试
{
“op”:“添加”,
“路径”:“/candb/foo”,
“价值”:{
“messageId”:171,
“模板”:[17,34],
“重复率”:100,
“canPort”:0
}
}
结果
在我尝试将指定更改应用于JsonPatchDocument
的站点上抛出了一个InvalidCastException
地点:
var currentModelSnapshot=this.currentModelFilter(this.currentModel.Copy());
var snapshotWithChangesApplied=currentModelSnapshot.Copy();
diffDocument.ApplyTo(应用更改的快照);
例外情况:
无法将“Newtonsoft.Json.Serialization.JsonDictionaryContract”类型的对象强制转换为“Newtonsoft.Json.Serialization.JsonObjectContract”类型。
B.依赖动态JSON补丁 一个更有希望的攻击计划似乎依赖于,它涉及对
ExpandoObject
的实例执行补丁操作。这允许您使用JSON修补程序文档添加、删除或替换属性,因为您处理的是动态类型的对象
实施
内部密封类CanDatabaseModel:DeviceComponentModel
{
公共CanDatabaseModel()
{
this.Definitions=newexpandoobject();
}
[JsonProperty(PropertyName=“candb”)]
公共IDictionary定义{get;}
...
}
测试
{
“op”:“添加”,
“路径”:“/candb/foo”,
“价值”:{
“messageId”:171,
“模板”:[17,34],
“重复率”:100,
“canPort”:0
}
}
结果
进行此更改允许我的测试的这一部分在运行时不会引发异常,但JSON修补程序不知道将值
反序列化为什么,导致数据作为作业对象
而不是CanMessageDefinition
存储在字典中:
有没有可能“告诉”JSON补丁如何反序列化信息?也许是类似于在定义
上使用JsonConverter
属性的东西
[JsonProperty(PropertyName=“candb”)]
[JsonConverter(…)]
公共IDictionary定义{get;}
总结
- 我需要支持向字典添加值的JSON补丁请求
- 我试着走纯静态路线,但失败了
- 我尝试过使用动态JSON补丁
- 这部分起作用,但我的数据存储为
类型,而不是预期的类型JObject
- 是否有一个属性(或其他技术)可以应用于我的属性,使其反序列化为正确的类型(而不是匿名类型)
- 这部分起作用,但我的数据存储为
DynamicDeserialisationStore
的类,它继承并利用JSON补丁对动态对象的支持
更具体地说,该类重写方法,如TrySetMember
、TrySetIndex
、TryGetMember
,本质上就像一个字典,只是它将所有这些操作委托给
internal sealed class DynamicDeserialisationStore<T> : DynamicObject, IDictionary<string, object> where T : class
{
private readonly Action<string, T> storeValue;
private readonly Func<string, bool> removeValue;
private readonly Func<string, T> retrieveValue;
private readonly Func<IEnumerable<string>> retrieveKeys;
public DynamicDeserialisationStore(
Action<string, T> storeValue,
Func<string, bool> removeValue,
Func<string, T> retrieveValue,
Func<IEnumerable<string>> retrieveKeys)
{
this.storeValue = storeValue;
this.removeValue = removeValue;
this.retrieveValue = retrieveValue;
this.retrieveKeys = retrieveKeys;
}
public int Count
{
get
{
return this.retrieveKeys().Count();
}
}
private IReadOnlyDictionary<string, T> AsDict
{
get
{
return (from key in this.retrieveKeys()
let value = this.retrieveValue(key)
select new { key, value })
.ToDictionary(it => it.key, it => it.value);
}
}
public override bool TrySetIndex(SetIndexBinder binder, object[] indexes, object value)
{
if (indexes.Length == 1 && indexes[0] is string && value is JObject)
{
return this.TryUpdateValue(indexes[0] as string, value);
}
return base.TrySetIndex(binder, indexes, value);
}
public override bool TryGetIndex(GetIndexBinder binder, object[] indexes, out object result)
{
if (indexes.Length == 1 && indexes[0] is string)
{
try
{
result = this.retrieveValue(indexes[0] as string);
return true;
}
catch (KeyNotFoundException)
{
// Pass through.
}
}
return base.TryGetIndex(binder, indexes, out result);
}
public override bool TrySetMember(SetMemberBinder binder, object value)
{
return this.TryUpdateValue(binder.Name, value);
}
public override bool TryGetMember(GetMemberBinder binder, out object result)
{
try
{
result = this.retrieveValue(binder.Name);
return true;
}
catch (KeyNotFoundException)
{
return base.TryGetMember(binder, out result);
}
}
private bool TryUpdateValue(string name, object value)
{
JObject jObject = value as JObject;
T tObject = value as T;
if (jObject != null)
{
this.storeValue(name, jObject.ToObject<T>());
return true;
}
else if (tObject != null)
{
this.storeValue(name, tObject);
return true;
}
return false;
}
object IDictionary<string, object>.this[string key]
{
get
{
return this.retrieveValue(key);
}
set
{
this.TryUpdateValue(key, value);
}
}
public IEnumerator<KeyValuePair<string, object>> GetEnumerator()
{
return this.AsDict.ToDictionary(it => it.Key, it => it.Value as object).GetEnumerator();
}
public void Add(string key, object value)
{
this.TryUpdateValue(key, value);
}
public bool Remove(string key)
{
return this.removeValue(key);
}
#region Unused methods
bool ICollection<KeyValuePair<string, object>>.IsReadOnly
{
get
{
throw new NotImplementedException();
}
}
ICollection<string> IDictionary<string, object>.Keys
{
get
{
throw new NotImplementedException();
}
}
ICollection<object> IDictionary<string, object>.Values
{
get
{
throw new NotImplementedException();
}
}
void ICollection<KeyValuePair<string, object>>.Add(KeyValuePair<string, object> item)
{
throw new NotImplementedException();
}
void ICollection<KeyValuePair<string, object>>.Clear()
{
throw new NotImplementedException();
}
bool ICollection<KeyValuePair<string, object>>.Contains(KeyValuePair<string, object> item)
{
throw new NotImplementedException();
}
bool IDictionary<string, object>.ContainsKey(string key)
{
throw new NotImplementedException();
}
void ICollection<KeyValuePair<string, object>>.CopyTo(KeyValuePair<string, object>[] array, int arrayIndex)
{
throw new NotImplementedException();
}
IEnumerator IEnumerable.GetEnumerator()
{
throw new NotImplementedException();
}
bool ICollection<KeyValuePair<string, object>>.Remove(KeyValuePair<string, object> item)
{
throw new NotImplementedException();
}
bool IDictionary<string, object>.TryGetValue(string key, out object value)
{
throw new NotImplementedException();
}
#endregion
}
public class DynamicDeserialisationStoreTests
{
private readonly FooSystemModel fooSystem;
public DynamicDeserialisationStoreTests()
{
this.fooSystem = new FooSystemModel();
}
[Fact]
public void Store_Should_Handle_Adding_Keyed_Model()
{
// GIVEN the foo system currently contains no foos.
this.fooSystem.Foos.ShouldBeEmpty();
// GIVEN a patch document to store a foo called "test".
var request = "{\"op\":\"add\",\"path\":\"/foos/test\",\"value\":{\"number\":3,\"bazzed\":true}}";
var operation = JsonConvert.DeserializeObject<Operation<FooSystemModel>>(request);
var patchDocument = new JsonPatchDocument<FooSystemModel>(
new[] { operation }.ToList(),
new CamelCasePropertyNamesContractResolver());
// WHEN we apply this patch document to the foo system model.
patchDocument.ApplyTo(this.fooSystem);
// THEN the system model should now contain a new foo called "test" with the expected properties.
this.fooSystem.Foos.ShouldHaveSingleItem();
FooModel foo = this.fooSystem.Foos["test"] as FooModel;
foo.Number.ShouldBe(3);
foo.IsBazzed.ShouldBeTrue();
}
[Fact]
public void Store_Should_Handle_Removing_Keyed_Model()
{
// GIVEN the foo system currently contains a foo.
var testFoo = new FooModel { Number = 3, IsBazzed = true };
this.fooSystem.Foos["test"] = testFoo;
// GIVEN a patch document to remove a foo called "test".
var request = "{\"op\":\"remove\",\"path\":\"/foos/test\"}";
var operation = JsonConvert.DeserializeObject<Operation<FooSystemModel>>(request);
var patchDocument = new JsonPatchDocument<FooSystemModel>(
new[] { operation }.ToList(),
new CamelCasePropertyNamesContractResolver());
// WHEN we apply this patch document to the foo system model.
patchDocument.ApplyTo(this.fooSystem);
// THEN the system model should be empty.
this.fooSystem.Foos.ShouldBeEmpty();
}
[Fact]
public void Store_Should_Handle_Modifying_Keyed_Model()
{
// GIVEN the foo system currently contains a foo.
var originalFoo = new FooModel { Number = 3, IsBazzed = true };
this.fooSystem.Foos["test"] = originalFoo;
// GIVEN a patch document to modify a foo called "test".
var request = "{\"op\":\"replace\",\"path\":\"/foos/test\", \"value\":{\"number\":6,\"bazzed\":false}}";
var operation = JsonConvert.DeserializeObject<Operation<FooSystemModel>>(request);
var patchDocument = new JsonPatchDocument<FooSystemModel>(
new[] { operation }.ToList(),
new CamelCasePropertyNamesContractResolver());
// WHEN we apply this patch document to the foo system model.
patchDocument.ApplyTo(this.fooSystem);
// THEN the system model should contain a modified "test" foo.
this.fooSystem.Foos.ShouldHaveSingleItem();
FooModel foo = this.fooSystem.Foos["test"] as FooModel;
foo.Number.ShouldBe(6);
foo.IsBazzed.ShouldBeFalse();
}
#region Mock Models
private class FooModel
{
[JsonProperty(PropertyName = "number")]
public int Number { get; set; }
[JsonProperty(PropertyName = "bazzed")]
public bool IsBazzed { get; set; }
}
private class FooSystemModel
{
private readonly IDictionary<string, FooModel> foos;
public FooSystemModel()
{
this.foos = new Dictionary<string, FooModel>();
this.Foos = new DynamicDeserialisationStore<FooModel>(
storeValue: (name, foo) => this.foos[name] = foo,
removeValue: name => this.foos.Remove(name),
retrieveValue: name => this.foos[name],
retrieveKeys: () => this.foos.Keys);
}
[JsonProperty(PropertyName = "foos")]
public IDictionary<string, object> Foos { get; }
}
#endregion
}
var dataDict = JsonConvert.DeserializeObject<Dictionary<string, object>>(json);
Dictionary<string, CanMessageDefinition> updateData = new Dictionary<string, CanMessageDefinition>();
foreach (var record in dataDict)
{
CanMessageDefinition recordValue = (CanMessageDefinition)record.Value;
if (yourExistingRecord.KeyAttributes.Keys.Contains(record.Key) && (!yourExistingRecord.KeyAttributes.Values.Equals(record.Value)))
{
updateData.Add(record.Key, recordValue);
}
}