How to make Primary key Auto increment while using Composite Primary keys in Room persistent library?

Question

I am using Room persistent library. I have requirement to add two primary keys in one table and one of the primary key should be auto increment. I don't know exact syntax to achieve this. Below is my Model class:

@Entity(tableName = "newsPapers", primaryKeys =  {"news_paper_id","news_paper_name"}) public class SelectNewsModel {  private int news_paper_id;  @ColumnInfo(name = "image_url") private String imageUrl;  @ColumnInfo(name = "news_paper_name") private String newsPaperName; } 

I want to make "news_paper_id" to be auto incremented. How can i make it?

Answer 1

I found another way around for this problem because as per my knowledge after some R&D, we can not have auto increment property in Composite Primary keys. So I used indices and unique constraint here because Room does not have direct UNIQUE constraint till now. So below is my working code:

@Entity(tableName = "newsPapers", indices = {@Index(value =         {"news_paper_name"}, unique = true)}) public class SelectNewsModel {      @PrimaryKey(autoGenerate = true)     private int news_paper_id;      @ColumnInfo(name = "image_url")     private String imageUrl;      @ColumnInfo(name = "news_paper_name")     private String newsPaperName; }