Port migratus to next.jdbc

[ieugen]

PR for #182

There are some differences in how java.jdbc works and how next.jdbc works and I don't know what is the best way to handle this in migratus. migratus receives a db-spec and builds a connection that it uses as :connection . Most functions use this connection via this pattern:

 (sql/with-db-transaction [t-con db]
      (sql/db-do-commands
        t-con .... ) 

java.jdbc has a function db-find-connection that extracts the connection from the map. There is also logic to create a connection if one is not found.

next.jdbc does not have this so I implemented:

(defn connection-or-spec
  "Migration code from java.jdbc to next.jdbc .
   java.jdbc accepts a spec that contains a ^java.sql.Connection as :connection.
   Return :connection or the db spec."
  [db]
  (let [conn (:connection db)]
    (if conn conn db)))

[ieugen]

@yogthos : All tests pass for this. I ported just a few functions but I think most will follow the pattern with connection-or-spec (see above).

[ieugen]

@yogthos : In this context modify-sql-fn receives an vector which is not as documented in the README - where the function expects a string.

(sql-mig/do-commands
     t-con
     (modify-sql-fn
      [(str "ALTER TABLE " table-name " ADD COLUMN description varchar(1024)")
       (str "ALTER TABLE " table-name " ADD COLUMN applied timestamp")]))

p.s. Migrated this to jdbc/execute-batch!

[ieugen]

So I tested this with PostgreSQL migration from the work project and got some failures in the way configuration is handled. Started a discussion on Slack and posting here to have issue history:

looking at the code I think the feature with :connection and :datasource was broken for some time.: Database gets the config with :db {:connection xxx }

(defrecord Database [connection config]
proto/Store
(config [this] config)
(init [this]
(let [conn (connect* (assoc (:db config) :transaction? (:init-in-transaction? config)))]

then in connect* we have (had):

(defn connect* [db]
(let [^Connection conn
(cond
(instance? Connection db) db
(instance? DataSource db) (try (.getConnection ^DataSource db)
(catch Exception e
(log/error e (str "Error getting DB connection from source" db))))
:else (try
(sql/get-connection db)
(catch Exception e
(log/error e (str "Error creating DB connection for "
(utils/censor-password db))))))]

connect* checks the db var with instance? , not (:connection db) as is documented in README things in docs changed at this point https://github.com/yogthos/migratus/pull/183/files

what is the way to go here?

[yogthos]

Yup, that looks like a bug. Probably would make sense to assume there is a :connection key going forward, and then do update on it?