Golang-格式化和存储后时间戳丢失的年份

Question

I am using the Go runtime to store entities in the Appengine Datastore sequenced by the time they were added; to store the timestamp in the key I am formatting the timestamp using the time.Time.String() method and storing the string version as the key.

To get the Time back again on retrieval I use time.Parse:

time.Parse("2006-01-02 15:04:05.000000000 +0000 UTC", the_timestamp)

In unit testing this functionality independent of an app (using cmdline - goapp test) my tests retrieve the timestamp in its entirety no problem.

But when I import the package doing this into an appengine app and test it (using cmdline - goapp serve) the timestamp is stored with its Year field set to "0000"

Answer 1

When you are converting your time to string before saving into datastore, the extra 0s at the end of time are removed. So,

2009-11-10 23:00:00.12300000 +0000 UTC

is converted into

2009-11-10 23:00:00.123 +0000 UTC

Now when you retrieve it from datastore and use the Parse function, it tries to match upto 8 digits after decimal. Hence the error.

So, while converting the time into string, you need to Format the string so that 0s are not lost.

const layout = "2006-01-02 15:04:05.000000000 +0000 UTC"
t := time.Now()
tFormat := t.Format(layout)

http://play.golang.org/p/elr28mfMo8