Entity
@Target([AnnotationTarget.CLASS, AnnotationTarget.FILE]) class Entity
| androidx.room.Entity |
Marks a class as an entity. This class will have a mapping SQLite table in the database.
Each entity must have at least 1 field annotated with PrimaryKey. You can also use primaryKeys() attribute to define the primary key.
Each entity must either have a no-arg constructor or a constructor whose parameters match fields (based on type and name). Constructor does not have to receive all fields as parameters but if a field is not passed into the constructor, it should either be public or have a public setter. If a matching constructor is available, Room will always use it. If you don't want it to use a constructor, you can annotate it with Ignore.
When a class is marked as an Entity, all of its fields are persisted. If you would like to exclude some of its fields, you can mark them with Ignore.
If a field is transient, it is automatically ignored unless it is annotated with ColumnInfo, Embedded or Relation.
Example:
@Entity
public class Song {
@PrimaryKey
private final long id;
private final String name;
@ColumnInfo(name = "release_year")
private final int releaseYear;
public Song(long id, String name, int releaseYear) {
this.id = id;
this.name = name;
this.releaseYear = releaseYear;
}
public int getId() {
return id;
}
public String getName() {
return name;
}
public int getReleaseYear() {
return releaseYear;
}
}
Summary
Public constructors |
|
|---|---|
<init>(tableName: String, indices: Array<Index>, inheritSuperIndices: Boolean, primaryKeys: Array<String>, foreignKeys: Array<ForeignKey>, ignoredColumns: Array<String>)Marks a class as an entity. |
|
Properties |
|
|---|---|
| Array<ForeignKey> |
List of |
| Array<String> |
The list of column names that should be ignored by Room. |
| Array<Index> |
List of indices on the table. |
| Boolean |
If set to |
| Array<String> |
The list of Primary Key column names. |
| String |
The table name in the SQLite database. |
Public constructors
<init>
Entity(
tableName: String,
indices: Array<Index>,
inheritSuperIndices: Boolean,
primaryKeys: Array<String>,
foreignKeys: Array<ForeignKey>,
ignoredColumns: Array<String>)
Marks a class as an entity. This class will have a mapping SQLite table in the database.
Each entity must have at least 1 field annotated with PrimaryKey. You can also use primaryKeys() attribute to define the primary key.
Each entity must either have a no-arg constructor or a constructor whose parameters match fields (based on type and name). Constructor does not have to receive all fields as parameters but if a field is not passed into the constructor, it should either be public or have a public setter. If a matching constructor is available, Room will always use it. If you don't want it to use a constructor, you can annotate it with Ignore.
When a class is marked as an Entity, all of its fields are persisted. If you would like to exclude some of its fields, you can mark them with Ignore.
If a field is transient, it is automatically ignored unless it is annotated with ColumnInfo, Embedded or Relation.
Example:
@Entity
public class Song {
@PrimaryKey
private final long id;
private final String name;
@ColumnInfo(name = "release_year")
private final int releaseYear;
public Song(long id, String name, int releaseYear) {
this.id = id;
this.name = name;
this.releaseYear = releaseYear;
}
public int getId() {
return id;
}
public String getName() {
return name;
}
public int getReleaseYear() {
return releaseYear;
}
}
See Also
Properties
foreignKeys
val foreignKeys: Array<ForeignKey>
List of ForeignKey constraints on this entity.
| Return | |
|---|---|
Array<ForeignKey>: The list of ForeignKey constraints on this entity. |
ignoredColumns
val ignoredColumns: Array<String>
The list of column names that should be ignored by Room.
Normally, you can use Ignore, but this is useful for ignoring fields inherited from parents.
Columns that are part of an Embedded field can not be individually ignored. To ignore columns from an inherited Embedded field, use the name of the field.
| Return | |
|---|---|
| Array<String>: The list of field names. |
indices
val indices: Array<Index>
List of indices on the table.
| Return | |
|---|---|
| Array<Index>: The list of indices on the table. |
inheritSuperIndices
val inheritSuperIndices: Boolean
If set to true, any Index defined in parent classes of this class will be carried over to the current Entity. Note that if you set this to true, even if the Entity has a parent which sets this value to false, the Entity will still inherit indices from it and its parents.
When the Entity inherits an index from the parent, it is always renamed with the default naming schema since SQLite does not allow using the same index name in multiple tables. See Index for the details of the default name.
By default, indices defined in parent classes are dropped to avoid unexpected indices. When this happens, you will receive a RoomWarnings#INDEX_FROM_PARENT_FIELD_IS_DROPPED or RoomWarnings#INDEX_FROM_PARENT_IS_DROPPED warning during compilation.
| Return | |
|---|---|
| Boolean: True if indices from parent classes should be automatically inherited by this Entity, false otherwise. Defaults to false. |
primaryKeys
val primaryKeys: Array<String>
The list of Primary Key column names.
If you would like to define an auto generated primary key, you can use PrimaryKey annotation on the field with PrimaryKey#autoGenerate() set to true.
| Return | |
|---|---|
Array<String>: The primary key of this Entity. Can be empty if the class has a field annotated with PrimaryKey. |