如何将源类型转换器转换为房间

Question

我正在开发一个新闻应用程序并已实现，但我无法将模型类转换为模型类下面的类型转换器

 @Entity
@ForeignKey(entity = Source.class,parentColumns = "source", childColumns = "content")
public class Article {
    @PrimaryKey
    @SerializedName("source")
    @Expose
    @ColumnInfo(name ="source")
    @TypeConverters(SourceTypeConverter.class)
    private Source source;

    public Source getSource() {
        return source;
    }

    public void setSource(Source source) {
        this.source = source;
    }

    @SerializedName("author")
    @Expose
    @ColumnInfo(name = "author")
    private String author;
    @SerializedName("title")
    @Expose
    @ColumnInfo(name = "title")
    private String title;
    @SerializedName("description")
    @Expose
    @ColumnInfo(name = "description")
    private String description;
    @SerializedName("url")
    @Expose
    @ColumnInfo(name = "url")
    private String url;
    @SerializedName("urlToImage")
    @Expose
    @ColumnInfo(name = "urlToImage")
    private String urlToImage;

    @SerializedName("publishedAt")
    @Expose
    @ColumnInfo(name = "publishedAt")
    private String publishedAt;
    @SerializedName("content")
    @Expose
    @ColumnInfo(name = "content")
    private String content;





    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    public String getUrlToImage() {
        return urlToImage;
    }

    public void setUrlToImage(String urlToImage) {
        this.urlToImage = urlToImage;
    }

    public String getPublishedAt() {
        return publishedAt;
    }

    public void setPublishedAt(String publishedAt) {
        this.publishedAt = publishedAt;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

}

在我的 SourceTypeConverter 类下面

public class  SourceTypeConverter {

@TypeConverter
   public static Source ConvertSource(Source source){
   return source ==   null ? null : new Source(source);
}




}

在 Source.java 下面 公共类源{

@SerializedName("id")
@Expose
private String id;
@SerializedName("name")
@Expose
private String name;

public Source(Source source) {
}

public String getId() {
    return id;
}

public void setId(String id) {
    this.id = id;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

}

在下面我得到 C:\Users\Edgar\Desktop\Sport News\app\src\main\java\edgar\yodgorbek\sportnews\model\Article.java:18: 错误：无法弄清楚如何保存字段到数据库。您可以考虑为其添加类型转换器。 私有来源来源；

below my database class
@Database(entities = {Article.class}, version = 1, exportSchema = false)
public  abstract class SportNewsDatabase extends RoomDatabase {
  public  abstract SportNewsDao sportNewsDao();
}

Answer 1

根据我们在linkedin的聊天，我可以说你是个很忘恩负义的人。您的房间无法转换模型中的文件类型源的问题。因此，您需要从 Source 类创建转换器以键入支持的 sqlite。

根据您最新发布的代码，我可以说您尝试做错事。您有两个表：Source 和 Article。并且您想在文章中存储指向 Source 的链接。

1. 删除您的类型转换器
2. 阅读此http://androidkt.com/database-relationships/
3. 简而言之，您需要为文章中的来源创建外键。这是一对一的关系。