Question 109948 in Json Question posted in
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How to map JSON array to Java class in Spring Boot

I’m trying to get responce from another API convert it to Java clases and then sent to the front end using Spring Boot
I have JSON response from external API like this

{
    "status": {
        "timestamp": "2023-01-31T14:06:45.210Z",
        "error_code": 0,
        "error_message": null,
    },
    "data": [
        {
            "id": 7982,
            "name": "wc4qtz6py1i",
            "tags": [
                "40rcevshzab",
                "3ja25pufu0z"
            ],
            "quote": {
                "USD": {
                    "price": 0.2,
                },
                "BTC": {
                    "price": 7159,
                }
            }
        },
        {
            "id": 8742,
            "name": "uhso98ca",
            "tags": [
                "84jsjsaesxx",
                "sasdd5dda76"
            ],
            "quote": {
                "USD": {
                    "price": 6,
                },
                "BTC": {
                    "price": 1230,
                }
            }
        }
     ]
 }

I need to convert all of this to classes using Spring Boot. But how I should organize it?
The most question is about "Data" array.
For now I have something like this.

@AllArgsConstructor
@NoArgsConstructor
@Getter
@Setter
public class MainDTO{
    @JsonProperty("status")
    private Status status;
    @JsonProperty("data")
    private Data data;
}

@AllArgsConstructor
@NoArgsConstructor
@Getter
@Setter
public class Data {
    Coin[] coins;
}

@AllArgsConstructor
@NoArgsConstructor
@Getter
@Setter
public class Coin{
    @JsonProperty("id")
    private Integer id;
    @JsonProperty("name")
    private String name;
    private Map<String, Coin> quote;
}

But it doesn’t work. I have error:

I have error
Tue Jan 31 16:13:45 EET 2023
There was an unexpected error (type=Internal Server Error, status=500).
Error while extracting response for type [class com.example.myCoolApp.entity.MainDTO] and content type [application/json;charset=utf-8]
org.springframework.web.client.RestClientException: Error while extracting response for type [class com.example.myCoolApp.entity.CryptoDTO] and content type [application/json;charset=utf-8]
Tags:

2

Answers


  1. 0

    You do not need a Data class because data field in your json is not an object – it is an array of objects, in your case it is an array of Coin objects.

    Change it the next way:

    public class MainDTO{
    @JsonProperty("status")
    private Status status;
    @JsonProperty("data")
    private List<Coin> data;
}
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  2. 0

    It’s worth mentioning that the JSON in your example is incorrect due to extra commas. I presume the correct form should look like this:

    {
    "status": {
        "timestamp": "2023-01-31T14:06:45.210Z",
        "error_code": 0,
        "error_message": null
    },
    "data": [
        {
            "id": 7982,
            "name": "wc4qtz6py1i",
            "tags": [
                "40rcevshzab",
                "3ja25pufu0z"
            ],
            "quote": {
                "USD": {
                    "price": 0.2
                },
                "BTC": {
                    "price": 7159
                }
            }
        },
        {
            "id": 8742,
            "name": "uhso98ca",
            "tags": [
                "84jsjsaesxx",
                "sasdd5dda76"
            ],
            "quote": {
                "USD": {
                    "price": 6
                },
                "BTC": {
                    "price": 1230
                }
            }
        }
     ]
 }

    As for classes I would suggest you the next:

    @AllArgsConstructor
@NoArgsConstructor
@Getter
@Setter
public class MainDTO {
    @JsonProperty("status")
    private Status status;
    @JsonProperty("data")
    private List<Coin> coins;
}

@AllArgsConstructor
@NoArgsConstructor
@Getter
@Setter
public class Status {
    @JsonProperty("timestamp")
    private String timestamp;
    @JsonProperty("error_code")
    private Integer errorCode;
    @JsonProperty("error_message")
    private String errorMessage;
}

@AllArgsConstructor
@NoArgsConstructor
@Getter
@Setter
public class Coin {
    @JsonProperty("id")
    private Integer id;
    @JsonProperty("name")
    private String name;
    @JsonProperty("tags")
    private List<String> tags;
    @JsonProperty("quote")
    private Map<String, Quote> quote;
}

@AllArgsConstructor
@NoArgsConstructor
@Getter
@Setter
public class Quote {
    @JsonProperty("price")
    private Double price;
}

    The "data" array in the JSON response is an array of coins, so the coins property in the MainDTO class should be of type List<Coin>.

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