Question

我正在开发新闻应用程序并实施，但无法将模型类转换为模型类下面的typeconverter

 @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SourceTypeConverter类之下

public class  SourceTypeConverter {

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




}

在Source.java下面公共类来源{

@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此文件字段放入数据库。您可以考虑为其添加类型转换器。私人来源；

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上的聊天，我可以说你是一个非常忘恩负义的人。您的房间无法转换模型中存在的文件类型Source的问题。因此，您需要从Source类创建转换器以键入sqlite支持的类型。

根据您最新发布的代码，我可以说您尝试做错什么。您有两个表：“来源”和“文章”。并且您想将到Source的链接存储在Article中。

删除类型转换器
阅读此http://androidkt.com/database-relationships/
简而言之，您需要在Article中为Source创建外键。这是一对一的关系。

如何将源类型转换器转换为房间

1 个答案: