CODEWITHSUNDEEP
joinforeign-keyssequelize.js
vanessa
vanessa

Reputation: 451

Sequelize : how to join on foreign keys

I'm using Sequelize and Node.js, and I need to join 2 tables on 2 foreign keys,

tableA.hasOne(tableB, { foreignKey: 'fk_tableB' });
tableB.belongsTo(tableA, {foreignKey: 'fk_tableB' });

(by the way, I don't understand the functionality of "targetKey") but I can only obtain a join on tableA.primaryKey = tableB.fk_tableB. How can I replace the tableA.primaryKey by tableA.fk_tableA?

I also tried to define twice tableA : in 2 different structures (one with the real primary key and the other with fk_tableA as primary key), but it's also not working (because I need the real tableA mode in another place).

Has someone an idea? Is it a bug from Sequelize?

Upvotes: 0

Views: 1547

Answers (1)

philipxy
philipxy

Reputation: 15157

How can I replace the tableA.primaryKey by tableA.fk_tableA?

There is no tableA.fk_tableA. But if there were, we would expect you to have named it that because column tableA.fk_tableA is a FK to a key column in tableA. Because that's the convention for naming a column fk_tableA. Similarly we would expect a belongTo like yours that adds a column that is a FK to the tableA PK to call it fk_tableA, not fk_tableB. Just like your hasOne gives tableA a column fk_tableB to the tableB PK. (If you want a FK to be to some other column than the PK then you say so via targetKey.)

If you so named FKs after their target table, you seem to want tableA.fk_tableB = tableB.fk_tableA. The way you have named them now, you seem to want tableA.fk_tableB = tableB.fk_tableB.

I need to join 2 tables on 2 foreign keys

It is extremely unlikely that you need the join above. Declaring a column to be a FK says that a value of the source/referencing column is always a value of the target/referenced column. Here targets are PKs. Such a join on a FK to one table and a FK to another table will only return rows that share the same PK value, even though the PKs are from different tables.

Upvotes: 1

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