I have this data structure:

public class AutoCompleteObject
{
    public Predictions[] predictions { get; set; }
    public string status { get; set; }
}

public class Predictions
{
    public string description { get; set; }
}

and this is the result of my api:

{
    "predictions": [
        {
            "description": "Hoisberg 142, Hamburg, Germany",
            "matched_substrings": [
                {
                    "length": 8,
                    "offset": 0
                },
                {
                    "length": 2,
                    "offset": 9
                },
                {
                    "length": 7,
                    "offset": 13
                }
            ],
            "place_id": "ChIJr_7fvYSKsUcRejFkuj1Nr0o",
            "reference": "ChIJr_7fvYSKsUcRejFkuj1Nr0o",
            "structured_formatting": {
                "main_text": "Hoisberg 143",
                "main_text_matched_substrings": [
                    {
                        "length": 8,
                        "offset": 0
                    },
                    {
                        "length": 2,
                        "offset": 9
                    }
                ],
                "secondary_text": "Hamburg, Germany",
                "secondary_text_matched_substrings": [
                    {
                        "length": 7,
                        "offset": 0
                    }
                ]
            },
         

        }
    ],
    "status": "OK"
}

I am trying to deserialize into my object using this:

ObservableCollection<AutoCompleteObject> res = JsonConvert.DeserializeObject<ObservableCollection<AutoCompleteObject>>(content);

But it fails stating it was unable to put the string into the array. But the result is an array and can contain many elements. What am I missing?

CodePudding user response：

The exception thrown is the following

Cannot deserialize the current JSON object (e.g. {"name":"value"}) into type 'System.Collections.ObjectModel.ObservableCollection`1[AutoCompleteObject]' because the type requires a JSON array (e.g. [1,2,3]) to deserialize correctly. To fix this error either change the JSON to a JSON array (e.g. [1,2,3]) or change the deserialized type so that it is a normal .NET type (e.g. not a primitive type like integer, not a collection type like an array or List) that can be deserialized from a JSON object. JsonObjectAttribute can also be added to the type to force it to deserialize from a JSON object.

So the exception point to the problem being that it expects an array. If you look at the json example you provided it starts with { which means it's a json object. To fix it you need to wrap the json object in [] or deserialize to a different class.

For example your json would have to look like this:

[
    {
        "predictions": [
            {
                "description": "Hoisberg 142, Hamburg, Germany",
                "matched_substrings": [
                    {
                        "length": 8,
                        "offset": 0
                    },
                    {
                        "length": 2,
                        "offset": 9
                    },
                    {
                        "length": 7,
                        "offset": 13
                    }
                ],
                "place_id": "ChIJr_7fvYSKsUcRejFkuj1Nr0o",
                "reference": "ChIJr_7fvYSKsUcRejFkuj1Nr0o",
                "structured_formatting": {
                    "main_text": "Hoisberg 143",
                    "main_text_matched_substrings": [
                        {
                            "length": 8,
                            "offset": 0
                        },
                        {
                            "length": 2,
                            "offset": 9
                        }
                    ],
                    "secondary_text": "Hamburg, Germany",
                    "secondary_text_matched_substrings": [
                        {
                            "length": 7,
                            "offset": 0
                        }
                    ]
                }
            }
        ],
        "status": "OK"
    }
]