Question

我从我的服务器接收此JSON。我的要求与通常的用例略有不同，因此这个问题。就我而言，我使用了Room库提供的@Embedded。

[
{
    "id": 105,
    "title": "Clear notification",
    "message": "Opening the app should automatically clear the notifications",
    "klass": "Demo",
    "priority": 0,
    "timestamp": "2017-09-03T07:20:56.130500Z",
    "teacher": "ABC",
    "attachments": []
},
{
    "id": 104,
    "title": "Attachment",
    "message": "File upload take 1",
    "attachments": [
        {
            "id": 5,
            "name": "Technology List.txt",
            "url": "https://cdn.filestackcontent.com/",
            "type": "text/plain",
            "size": 954
        }
    ]
}

上述JSON的POJO。我将JSON反序列化为FeedWithAttachment类。

public class FeedWithAttachment {
    @NotNull @Embedded
    public Feed feed; 
    @Relation(parentColumn = "id", entityColumn = "feedId", entity = Attachment.class)       
    public List<Attachment> attachments;

}

我的Feed类：

data class Feed(
        @PrimaryKey @SerializedName("id")
        var id: Long = 0,

        @SerializedName("title")
        var title: String = "",

        @SerializedName("message")
        var message: String = "",
)

我的附件类：

data class Attachment(
        @PrimaryKey @SerializedName("id")
        var attachmentId: Int = 0,
        var name: String = "",
        var url: String = "",
        var type: String = "",
        var size: Long = 0,
        @Transient
        var feedId: Long = 0
)

如果我们将List<Attachment放在Feed模型中，那么它会按预期工作。不幸的是，我的要求是需要另一个名为FeedWithAttachment的类。

改造：

interface FeedService {
    public Call<List<FeedWithAttachment>> getFeeds();
}

问题

我在FeedWithAttachment为feed且null符合预期的回复中获得attachments。

Answer 1

在FeedWithAttachment中编写Feed变量时，请尝试查找＆＃34; feed＆＃34;在json的钥匙。类中定义的每个变量名必须存在于json的键中。你使用这个类：

public class FeedWithAttachment {
    int id;
    String title;
    String message;
    String klass;
    int priority;
    String timestamp;
    String teacher;

    List<Attachment> attachments;
}

和Attachment.class：

public class Attachment{
    int id;
    String name;
    String url;
    String type;
    int size;
}

使用Retrofit将JSON反序列化为Room Embedded Class

1 个答案: