Modify time:now() to be less one hour

First of all, I don't quite know what the core language is of this. I have followed a tutorial.

My code looks like this:

{
    "type": "dateRange",
    "dateRange": "${time:extractStringFromDateTZ(time:now(), 'UTC', 'yyyy-MM-dd\'T\'HH:mm:ss.SSS')}/${time:extractStringFromDateTZ(time:now(), 'UTC', 'yyyy-MM-dd\'T\'HH:mm:ss.SSS')}"
}

This gives me the following:

{
    "type": "dateRange",
    "dateRange": "2019-04-01T00:00:00.000/2019-04-01T00:00:00.000"
}

What I am trying to do is take 1h off the first date. This is what I have tried:

Before:

${time:extractStringFromDateTZ(time:now(), 'UTC', 'yyyy-MM-dd\'T\'HH:mm:ss.SSS')}

After:

${time:millisecondsToDateTime(time:dateTimeToMilliseconds(time:now()) - (3600), 'UTC', 'yyyy-MM-dd\'T\'HH:mm:ss.SSS')}

Although this seems to be valid code, it says its invalid. Please can someone help me understand how to modify the "before" code to be 1 hour from the time now.

Solution

First, as mentioned in the comments to your post, 1h is 3600000 milliseconds

Then, I never worked with StreamSets but looking at the doc:

the signature of the method you try to use is time:dateTimeToMilliseconds(<Date object>) and it returns a Long Its description is:

Converts a Date object to an epoch or UNIX time in milliseconds.

So you can't call it with these parameters , 'UTC', 'yyyy-MM-dd\'T\'HH:mm:ss.SSS'

This might be the valid syntax it is expecting:

${time:millisecondsToDateTime(time:dateTimeToMilliseconds(time:now()) - (3600000))}

You should be using other functions if you want to use a time zone:

time:millisecondsToDateTime(<long>) returns a Date object and time:extractStringFromDateTZ(<Date object>, <time zone>, <format string>) returns a String

Can't you chain them like this?

${time:extractStringFromDateTZ(
    time:millisecondsToDateTime(time:dateTimeToMilliseconds(time:now()) - 3600000), 
    'UTC', 
    'yyyy-MM-dd\'T\'HH:mm:ss.SSS')}