Android Room FOREIGN KEY约束失败(代码787)

问题描述

我想用两个外键在Android Room中创建一个数据库.每次我尝试在数据库中插入曲目时，程序都会崩溃，并说外键costraint失败(代码787)".也许你们中的某人知道原因，并且可以帮助我.

I'm tying to create a database in Android Room with two foreign keys. Every time I try to insert a track into the database the program chrashes and says that the "foreign key costraint failed(code 787)". Maybe someone of you knows why and can help me.

@Entity(foreignKeys = {@ForeignKey(
    entity = Kategorie.class,
    childColumns = "kategorieFremdschluessel",
    parentColumns = "kategorieID",
    onUpdate = ForeignKey.CASCADE,
    onDelete = ForeignKey.CASCADE
    ),
    @ForeignKey(
            entity = Playlist.class,
            childColumns = "playlistFremdschluessel",
            parentColumns = "uuid",
            onUpdate = ForeignKey.CASCADE,
            onDelete = ForeignKey.CASCADE
    )
 })

public class Track {

@PrimaryKey(autoGenerate = true)
private int uid;

private String trackTitel;
private String playlistName;
private String jsonObjectString;
private int kategorieFremdschluessel;
private int playlistFremdschluessel;

@Ignore
public Track(String trackTitel, String playlistName, String jsonObjectString) {
    this.trackTitel = trackTitel;
    this.playlistName = playlistName;
    this.jsonObjectString = jsonObjectString;
}

public Track(String trackTitel, String jsonObjectString) {
    this.trackTitel = trackTitel;
    this.jsonObjectString = jsonObjectString;
}
//Getter and Setter

@Dao

TrackDao

public interface TrackDao {

@Query("SELECT * FROM Track WHERE playlistName LIKE :playlist")
List<Track> getAllTracks(String playlist);

@Query("SELECT * FROM Track WHERE kategorieFremdschluessel = :kategorieFremdschluessel")
List<Track> loadAllKategorieTracks(int kategorieFremdschluessel);

@Query("SELECT * FROM Track WHERE playlistFremdschluessel = :playlistFremdschluessel")
List<Track> loadAllPlaylistTracks(int playlistFremdschluessel);

@Insert
void insertAll(List<Track> trackList);

@Insert
void insertOne(Track track);

@Update
void updateOne(Track track);

@Delete
void delete(Track track);
}

类别"和播放列表"也是数据库中的表.

"Kategorie" and "Playlist" are also tables in the database.

@Entity
public class Playlist{


@PrimaryKey(autoGenerate = true)
private int uuid;

@ColumnInfo(name = "name")
private String name;

类别

@Entity
public class Kategorie {



@PrimaryKey(autoGenerate = true)
private int kategorieID;


@ColumnInfo(name = "name")
private String name;

推荐答案

您需要在表Kategorie和Playlist中的行具有相同的外键，就像您要插入的Track一样.

You need to have rows in tables Kategorie and Playlist with a same foreign key as has Track that you are inserting.

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