Question

Using the clojure jdbc library with postgresql. I have a table “xxx” with a timestamp column “created_at” in postgresql, and I have a string containing a date in the right format. Doing an insert fails:

(require '[clojure.java.jdbc :as sql])

(sql/with-connection *db*
  (sql/insert-record :xxx {:created_at "Thu Feb 09 10:38:01 +0000 2012"}))

Here is the error:

org.postgresql.util.PSQLException: ERROR: column "created_at" 
is of type timestamp with time zone but expression is of type character varying

So I understand that postgres requires a timestamp value, but how do I convert my string representation of the date into something postgres will accept? java.util.Date fails also, and I can’t find any docs on the clojure postgres library.

Thanks!

Answer 1

You’ll need to pass in a java.sql.Timestamp instance. To parse your string into one using clj-time, a Joda-Time-wrapping library for Clojure, you’d do something along the following lines:

(require '(clj-time [format :as timef] [coerce :as timec])

(->> "Thu Feb 09 10:38:01 +0000 2012"
     (timef/parse (timef/formatter "EEE MMM dd HH:mm:ss Z yyyy"))
     timec/to-timestamp)

The returned value can then be passed to PostgreSQL via JDBC.

In case you’re obtaining the date in some other string format and converting it to this one, you could skip the conversion and provide an appropriate formatter for the original representation. There are quite a few available by default in the clj-time.format/formatters map, say (clj-time.format/show-formatters) at the REPL to see a list with examples. Also, clj-time.coerce/from-string tries all default formatters in sequence returning the value of the first succeeding parse (nil if there is none). If you’re obtaining the date as a java.util.Date or a long, see from-date and from-long in the same namespace.

Use [clj-time "0.3.6"] as the dependency specifier in your project.clj if you decide to use clj-time.

Alternatively, you could use some other way of parsing your timestamp string into a java.sql.Timestamp; Timestamp itself can parse a different string representation:

(java.sql.Timestamp/valueOf "2004-10-19 10:23:54")

clj-time is the most sane way of dealing with date and time in Clojure, though, so it’s likely to be worth your while.