如何找到项目的类，然后将其反序列化为对象？

Question

I am calling a method like this:

await App.CDB.InsertLogItem(logStart);
await App.CDB.InsertLogItem(logViews);

LogStart and LogViews are two classes that inherit from LogBase

Here's the method signature:

public async Task<bool> InsertLogItem(LogBase item) {
   await client.CreateDocumentAsync(collectionLink, item);
}

For the case where there is no internet connectivity I am planning to store the value of item and then later replay it like this:

public InsertLogItem(LogBase item) {
   string result = JsonConvert.SerializeObject(item);
   // store result as a string and possible somehow class name in a database row  
}

 public async Task<bool> InsertFromDatabase {
   string result = get result from database
   // get result and possible class from database and convert into item
   // this is the part that I am not sure how to do.
   return await client.CreateDocumentAsync(collectionLink, item);
}

How can I convert result back to item here? I assume I need to know the class but how can I find the class?

Answer 1

If you save both the serialized item as well as his type, you can deserialize, getting the type at run time.

Code:

public class BaseClass
{
    public string MyProperty0 { get; set; }
}

public class TestClass : BaseClass
{
    public int MyProperty1 { get; set; }
    public string MyProperty2 { get; set; }
}

public static string SerializeBaseClass<T>(T item) where T : BaseClass
{
    return JsonConvert.SerializeObject(item);
}

static void Main(string[] args)
{
    var item = new TestClass { MyProperty0 = "11111", MyProperty1 = 1, MyProperty2 = "1111" };

    string serializedItem, serializedType;

    serializedType = item.GetType().FullName;
    serializedItem = SerializeBaseClass(item);

    Console.WriteLine(serializedType);
    Console.WriteLine(serializedItem);

    var deserializedType = Type.GetType(serializedType);
    var deserializedItem = JsonConvert.DeserializeObject(serializedItem, deserializedType);

    Console.WriteLine(deserializedItem.GetType().FullName);

    Console.ReadKey();
}

Result:

Test001.Program+TestClass
{"MyProperty1":1,"MyProperty2":"1111","MyProperty0":"11111"}
Test001.Program+TestClass

As you can see, the object is deserialized to the correct type

Answer 2

You can make your method generic and constrain the open type to something that is or derives from LogBase . Your Document should contain everything the original class had:

public async Task<bool> InsertLogItem<T>(T item) where T: LogBase 
{
   string result = JsonConvert.SerializeObject(item);
   await client.CreateDocumentAsync(collectionLink, item);
}