Merge pull request clj-time#12 from r0man/coerce-protocol

Coerce protocol

src/clj_time/coerce.clj

@@ -1,53 +1,99 @@
 (ns clj-time.coerce
   "Utilites to coerce Joda DateTime instances to and from various other types.
    For example, to convert a Joda DateTime to and from a Java long:
-   
+
      => (to-long (date-time 1998 4 25))
      893462400000
-     
+
      => (from-long 893462400000)
      #<DateTime 1998-04-25T00:00:00.000Z>"
   (:refer-clojure :exclude [extend])
   (:use clj-time.core)
   (:require [clj-time.format :as time-fmt])
   (:import (org.joda.time DateTime DateTimeZone))
-  (:import java.util.Date))
+  (:import java.util.Date java.sql.Timestamp))
 
-(defn to-long
-  "Returns the number of milliseconds that the given DateTime is after Unix
-   epoch."
-  [#^DateTime dt]
-  (.getMillis dt))
+(defprotocol ICoerce
+  (to-date-time [obj] "Convert `obj` to a Joda DateTime instance."))
 
 (defn from-long
   "Returns a DateTime instance in the UTC time zone corresponding to the given
    number of milliseconds after the Unix epoch."
-   [#^Long millis]
-   (DateTime. millis #^DateTimeZone utc))
+  [#^Long millis]
+  (DateTime. millis #^DateTimeZone utc))
 
 (defn from-string
   "return DateTime instance from string using
    formatters in clj-time.format, returning first
    which parses"
   [s]
   (first
-       (for [f (vals time-fmt/formatters)
-             :let [d (try (time-fmt/parse f s) (catch Exception _ nil))]
-             :when d] d)))
-
-(defn to-date
-  "Returns a Java Date object corresponding to the given DateTime instance."
-  [#^DateTime dt]
-  (Date. #^Long (to-long dt)))
+   (for [f (vals time-fmt/formatters)
+         :let [d (try (time-fmt/parse f s) (catch Exception _ nil))]
+         :when d] d)))
 
 (defn from-date
   "Returns a DateTime instance in the UTC time zone corresponding to the given
    Java Date object."
   [#^Date date]
   (from-long (.getTime date)))
 
+(defn to-long
+  "Convert `obj` to the number of milliseconds after the Unix epoch."
+  [obj]
+  (if-let [dt (to-date-time obj)]
+    (.getMillis dt)))
+
+(defn to-date
+  "Convert `obj` to a Java Date instance."
+  [obj]
+  (if-let [dt (to-date-time obj)]
+    (Date. (.getMillis dt))))
+
 (defn to-string
-  "Returns a string representation of date in UTC time-zone using
-   (ISODateTimeFormat/dateTime) date-time representation. "
-  [#^DateTime dt]
-  (time-fmt/unparse (:date-time time-fmt/formatters) dt))
+  "Returns a string representation of obj in UTC time-zone
+  using (ISODateTimeFormat/dateTime) date-time representation."
+  [obj]
+  (if-let [dt (to-date-time obj)]
+    (time-fmt/unparse (:date-time time-fmt/formatters) dt)))
+
+(defn to-timestamp
+  "Convert `obj` to a Java SQL Timestamp instance."
+  [obj]
+  (if-let [dt (to-date-time obj)]
+    (Timestamp. (.getMillis dt))))
+
+(extend-type nil
+  ICoerce
+  (to-date-time [_]
+    nil))
+
+(extend-type Date
+  ICoerce
+  (to-date-time [date]
+    (from-date date)))
+
+(extend-type DateTime
+  ICoerce
+  (to-date-time [date-time]
+    date-time))
+
+(extend-type Integer
+  ICoerce
+  (to-date-time [integer]
+    (from-long (long integer))))
+
+(extend-type Long
+  ICoerce
+  (to-date-time [long]
+    (from-long long)))
+
+(extend-type String
+  ICoerce
+  (to-date-time [string]
+    (from-string string)))
+
+(extend-type Timestamp
+  ICoerce
+  (to-date-time [timestamp]
+    (from-date timestamp)))

test/clj_time/coerce_test.clj

@@ -2,24 +2,72 @@
   (:refer-clojure :exclude [extend])
   (:use clojure.test)
   (:use (clj-time core coerce))
-  (:import java.util.Date))
+  (:import java.util.Date java.sql.Timestamp))
 
-(deftest test-to-long
-  (is (= 893462400000 (to-long (date-time 1998 4 25)))))
-
-(deftest test-from-long
-  (is (= (date-time 1998 4 25) (from-long 893462400000))))
-
-(deftest test-to-from-date
+(deftest test-from-date
   (let [dt (from-long 893462400000)
         d  (to-date dt)]
     (is (instance? Date d))
     (is (= dt (from-date d)))))
 
-(deftest test-to-string
-  (is (= (to-string (date-time 1998 4 25))
-	 "1998-04-25T00:00:00.000Z")))
+(deftest test-from-long
+  (is (= (date-time 1998 4 25) (from-long 893462400000))))
 
 (deftest test-from-string
   (is (= (from-string "1998-04-25T00:00:00.000Z")
-	 (date-time 1998 4 25))))
+         (date-time 1998 4 25))))
+
+(deftest test-to-date
+  (is (nil? (to-date nil)))
+  (is (nil? (to-date "")))
+  (is (nil? (to-date "x")))
+  (is (= (Date. 893462400000) (to-date (date-time 1998 4 25))))
+  (is (= (Date. 893462400000) (to-date (Date. 893462400000))))
+  (is (= (Date. (long 0)) (to-date 0)))
+  (is (= (Date. 893462400000) (to-date 893462400000)))
+  (is (= (Date. 893462400000) (to-date (Timestamp. 893462400000))))
+  (is (= (Date. 893462400000) (to-date "1998-04-25T00:00:00.000Z"))))
+
+(deftest test-to-date-time
+  (is (nil? (to-date-time nil)))
+  (is (nil? (to-date-time "")))
+  (is (nil? (to-date-time "x")))
+  (is (= (date-time 1998 4 25) (to-date-time (date-time 1998 4 25))))
+  (is (= (date-time 1998 4 25) (to-date-time (Date. 893462400000))))
+  (is (= (date-time 1970 1 1) (to-date-time 0)))
+  (is (= (date-time 1998 4 25) (to-date-time 893462400000)))
+  (is (= (date-time 1998 4 25) (to-date-time (Timestamp. 893462400000))))
+  (is (= (date-time 1998 4 25) (to-date-time "1998-04-25T00:00:00.000Z"))))
+
+(deftest test-to-long
+  (is (nil? (to-long nil)))
+  (is (nil? (to-long "")))
+  (is (nil? (to-long "x")))
+  (is (= 893462400000 (to-long (date-time 1998 4 25))))
+  (is (= 893462400000 (to-long (Date. 893462400000))))
+  (is (= (long 0) (to-long 0)))
+  (is (= 893462400000 (to-long 893462400000)))
+  (is (= 893462400000 (to-long (Timestamp. 893462400000))))
+  (is (= 893462400000 (to-long "1998-04-25T00:00:00.000Z"))))
+
+(deftest test-to-string
+  (is (nil? (to-string nil)))
+  (is (nil? (to-string "")))
+  (is (nil? (to-string "x")))
+  (is (= "1998-04-25T00:00:00.000Z" (to-string (date-time 1998 4 25))))
+  (is (= "1998-04-25T00:00:00.000Z" (to-string (Date. 893462400000))))
+  (is (= "1970-01-01T00:00:00.000Z" (to-string 0)))
+  (is (= "1998-04-25T00:00:00.000Z" (to-string 893462400000)))
+  (is (= "1998-04-25T00:00:00.000Z" (to-string (Timestamp. 893462400000))))
+  (is (= "1998-04-25T00:00:00.000Z" (to-string "1998-04-25T00:00:00.000Z"))))
+
+(deftest test-to-timestamp
+  (is (nil? (to-timestamp nil)))
+  (is (nil? (to-timestamp "")))
+  (is (nil? (to-timestamp "x")))
+  (is (= (Timestamp. 893462400000) (to-timestamp (date-time 1998 4 25))))
+  (is (= (Timestamp. 893462400000) (to-timestamp (Date. 893462400000))))
+  (is (= (Timestamp. (long 0)) (to-timestamp 0)))
+  (is (= (Timestamp. 893462400000) (to-timestamp 893462400000)))
+  (is (= (Timestamp. 893462400000) (to-timestamp (Timestamp. 893462400000))))
+  (is (= (Timestamp. 893462400000) (to-timestamp "1998-04-25T00:00:00.000Z"))))