Push Query for RxDB

For the push query we use an upsert:

Copy
    const pushQueryBuilder = doc => {
        const query = `
            mutation InsertTodo($todo: [todos_insert_input!]!) {
                insert_todos(
                    objects: $todo,
                    on_conflict: {
                        constraint: todos_pkey,
                        update_columns: [text, isCompleted, deleted, updatedAt]
                    }){
                    returning {
                    id
                    }
                }
        }
        `;
        const variables = {
            todo: doc
        };

        return {
            query,
            variables
        };
    };

RxDB will call the above method whenever a document is updated or a new document is created. RxDB will then fire the graphQL query returned along with the variables returned. In the above function the InsertTodo mutation tells hasura to try to insert the row only if a row with the same id does not already exist. If a row with the same id exists then Hasura will simply update the columns given in the update_columns field of that row.