I am new to Rust and I am making an API using Diesel and Actix-web. I have a DB in pgsql and mongodb and I use diesel 1.4.4 only for pgsql.
First, I did a test creating a DB with its tables and its primary keys and everything works fine. But, there are always scenarios in which there will be tables that do not have a primary key and only have foreign keys.
I have noticed that Diesel only supports table with Primary Keys, but if you wanted to use a table that does not have a primary key and only has a foreign key, is there a way to import that table? Manually can you? That is, defining it in the schema.rs and in my models.rs.
Tables without primary key are not supported by diesel, because they are bad practice from a database point of view. In almost all cases there is some combination of columns that form a natural primary key, otherwise adding a artificial one is preferred. If you have a table that consists only of foreign key columns the natural foreign key would be constructed out of all those columns.
That said: It is possible to use diesel with tables without primary key column by just telling diesel that a specific (combination) of columns should be treated as primary key. In this case you need to write your table! definition for those tables manually.