Why Does JSON Deserialization Fail When Trying to Convert an Object to a List?

JSON deserialization issue: Unable to convert object to list

When trying to deserialize a JSON object into a list of custom objects, developers may encounter the error: "Cannot deserialize the current JSON object (for example: {"name":"value"}) into Type 'System.Collections.Generic.List`1[...]'". This problem occurs when the JSON structure does not match the target deserialization type.

Consider the following code snippet:

string jsonstring = "{\"data\":[{\"target_id\":9503123,\"target_type\":\"user\"}]}";
List<RootObject> datalist = JsonConvert.DeserializeObject<List<RootObject>>(jsonstring);

In this scenario, the target deserialization type is List, which expects a JSON array of RootObject objects. However, the JSON string represents a single RootObject object, contained in an array named "data".

Solution:

To resolve this issue, the target deserialization type must be adjusted to align with the JSON structure.

Correct deserialization:

RootObject data = JsonConvert.DeserializeObject<RootObject>(jsonstring);

By changing the deserialization type to RootObject, the code is now aligned with the JSON structure and the deserialization process completes successfully without the above error. If you need to access target_id and target_type, you need to further process the data object, for example: data.data[0].target_id.

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