Why Does JSON Deserialization Fail When a List Type Expects Non-Array JSON Data?

Handling JSON deserialization errors: list type and non-array JSON data

When deserializing JSON data using Newtonsoft's JsonConvert, developers often encounter the error: "The current JSON object cannot be deserialized to type 'System.Collections.Generic.List`1[T]' because the type A JSON array is required to deserialize correctly ”

This error occurs when the target data type is a list (shown as 'List`1' in the error message), but the JSON data is not an array. To resolve this issue, you need to modify the JSON data to match the expected array format, or adjust the target data type to accept non-array formats.

JSON data conversion

If your JSON data is actually an array but is not represented in this form, you will need to convert it to array format before deserializing. You can use JSON.NET's JObject or JArray classes for this purpose. For example, if your JSON data is in the following format:

<code>{"data":[{"target_id":9503123,"target_type":"user"}]}</code>

You can use the following code to convert it to array format:

<code>JObject obj = JObject.Parse(jsonstring);
jsonstring = obj["data"].ToString();</code>

This will convert the JSON data into the following array format:

<code>[{"target_id":9503123,"target_type":"user"}]</code>

Adjust the target data type

If your JSON data is not an array, you need to adjust the target data type to accept non-array formats. In this case, you should change the List type to RootObject type. For example:

<code>RootObject datalist = JsonConvert.DeserializeObject<RootObject>(jsonstring);</code>

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