Room Sqlite 从保存为字符串的日期查询到 return unix 时间戳

Question

大家好，我会保持简单并展示 table/model 和查询的代码。尝试获取要作为 unix 时间戳返回的日期。当前查询未从数据库返回任何内容。

请查看下面的代码片段

TABLE CLASS

@Entity(tableName = "moodBeforeTable")
public class MoodBeforeTable {

@PrimaryKey(autoGenerate = true)
private long moodBeforePK;

@NonNull
@ColumnInfo(name = "userId")
private int userId;

@NonNull
@ColumnInfo(name = "moodBefore")
private int moodBefore;

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

@ColumnInfo(name = "cbtId")
private long cbtId;

POJO CLASS 用于 JOINS

public class MoodStatsLineGraphModel {

private long day, dayAfter;
private int moodBefore;
private long userId;
private long cbtId;
private int moodAfter;
private String workoutDate;

**Constructors getters/setters not shown to save space**
}

带有查询的 DAO

@Dao
public interface MoodStatsLineGraphDao {

@Query("SELECT strftime ('%s',moodBeforeTable.workoutDate)AS 'day', strftime ('%s',moodAfterTable.workoutDate) AS 'dayAfter', moodBeforeTable.moodBefore, moodBeforeTable.userId, moodBeforeTable.workoutDate, moodBeforeTable.cbtId, moodAfterTable.moodAfter, moodAfterTable.workoutDate " +
        "FROM moodBeforeTable " +
        "LEFT JOIN moodAfterTable ON moodBeforeTable.cbtId = moodAfterTable.cbtId " +
        "WHERE DATE(moodBeforeTable.workoutDate) >= datetime('now', '-1 month') " +
        //"AND moodBeforeTable.userId = '$getId' " +
        "OR moodBeforeTable.cbtId = NULL " +
        "ORDER BY moodBeforeTable.workoutDate ASC")
LiveData<List<MoodStatsLineGraphModel>> getMoodStatsMonthly();

Answer 1

您需要一个类型转换器。来自文档 https://developer.android.com/training/data-storage/room/referencing-data#java:

public class Converters {
    @TypeConverter
    public static Date fromTimestamp(Long value) {
        return value == null ? null : new Date(value);
    }

    @TypeConverter
    public static Long dateToTimestamp(Date date) {
        return date == null ? null : date.getTime();
    }

}

Room Sqlite 从保存为字符串的日期查询到 return unix 时间戳

Room Sqlite Query to return unix time stamp from date saved as String

sqlite

android

android-sqlite

android-room