我有一个Component包含外键来自Component_category

我的目的是通过选择的组件类别来过滤组件列表。

这两个类如下：

成分

@Entity(tableName = "component_table", foreignKeys = {
        @ForeignKey(
            entity = Rack.class,
            parentColumns = "rack_id",
            childColumns = "component_id",
            onDelete = ForeignKey.CASCADE,
            onUpdate = ForeignKey.CASCADE
        ),
        @ForeignKey(
            entity = ComponentCat.class,
            parentColumns = "component_cat_id",
            childColumns = "component_id",
            onDelete = ForeignKey.CASCADE,
            onUpdate = ForeignKey.CASCADE
        )
})

public class Component {

    @PrimaryKey(autoGenerate = true)
    @ColumnInfo(name = "component_id")
    public int componentID;

    @NonNull
    @ColumnInfo(name = "component_name")
    private String componentName;

    // .. omitted

组件类别

@Entity(tableName = "component_cat_table")

public class ComponentCat
{
    @PrimaryKey(autoGenerate = true)
    @ColumnInfo(name = "component_cat_id")
    public int componentCatID;

    @NonNull
    @ColumnInfo(name = "component_cat_name")
    private String componentCatName;

    // .. omitted

询问

我希望我的查询如下：

 @Query("SELECT * from component_table " +
        "INNER JOIN component_cat_table " +
        "WHERE component_table.component_cat_id == :categoryID ORDER BY component_name ASC")
        LiveData<List<Component>> getFilteredComponents(int categoryID);

但是在编译时它告诉我它无法解决component_table.component_cat_id。我也无法在Component课堂上的外键实体上设置名称。我尝试了一些选项，但在不“访问”外键的情况下不知道如何解决查询。