How to pass Java date as path variable in a rest get call

Question

There is an existing api which is having the below code :

@GetMapping(value = "/getAmount")
public long getAmount(){

    Date d = new Date();
    long amountFetchedFromDb = callToDatabase(d);
    return amountFetchedFromDb;
}

Now I need to change the functionality as below:

@GetMapping(value = "/getAmount")
public long getAmount(){

    Date d = new Date();
    <CALL TO A NEW  REST API PASSING IT THE DATE d AND THE NEW API 
     WILL MAKE THE DB CALL AND RETURN THE AMOUNT>
    return amount;
}

Now, I have created a new rest service which takes a java date as a path variable as below:

@GetMapping("/getAmount/{dateTo}")
public long getAmount(@PathVariable Date dateTo){

   long amountFetchedFromDb = callToDatabase(d);
   return amountFetchedFromDb;
}

Now i need to test my new service.How to pass the date in the request below:

http://localhost:8080/getAmount/?

There is no date format being used in the existing api. it just creates a java date and passes in the query to Db. No conversion. So, i am not sure what will it pass to me. So, what I did was created a simple rest service which returns new Date(). When I ran it, I got in response 1530137142067(Today is 27June). What format is this?

I hope this is not too confusing. Please let me know if my query is not clear.

Any reason why you are using the `Date` class? That class is long outdated. Today we have so much better in [`java.time`, the modern Java date and time API](https://docs.oracle.com/javase/tutorial/datetime/). I suggest that you can use ISO 8601 format for passing the date. It goes like 2018-06-28. `LocalTime` from `java.time` produces this format through its `toString` method and parses the same format back into a `LocalDate` without any explicit formatter. — Ole V.V., Jun 28 '18 at 08:16

score 9 · Answer 1 · answered Apr 26 '19 at 14:31

If you want to use a PathVariable, you can use the example method below:

//You can consume the path .../getAmount/2019-04-25
@GetMapping("/getAmount/{dateTo}")
public long getAmount(@PathVariable("dateTo") @DateTimeFormat(pattern = "yyyy-MM-dd") Date dateTo) {
    long amountFetchedFromDb = callToDatabase(dateTo);
    return amountFetchedFromDb;
}

score 4 · Answer 2 · answered Jun 27 '18 at 22:31

4

There a couple of ways to achieve this.

Pass in a simple String date as a path variable. Then use SimpleDateFormat to parse the String into a date object. Note here that in this way you'll be dealing with conversion that may fail. Also your clients should be aware of the date format they will be using. Not the very best approach in my opinion but do-able.

Pass in an number defining an epoch and use this to construct your date object. Assuming that you're not interested in very fine precision (nanoseconds etc) you should be fine.

So in case of the first option your get request would look like:

someurl/getAmount/28-06-2018/

For the second:

someurl/getAmount/1530137142067

In my opinion the latter is the best.

answered Jun 27 '18 at 22:31

akortex

5,067
2
25
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I used the second approach. I get the error:"message": "Failed to convert value of type 'java.lang.String' to required type 'java.util.Date'; nested exception is org.springframework.core.convert.ConversionFailedException: Failed to convert from type [java.lang.String] to type [@org.springframework.web.bind.annotation.PathVariable java.util.Date] for value '1530137142067'; nested exception is java.lang.IllegalArgumentException", – T Anna Jun 27 '18 at 22:53
I suppose you left the code this way: `@PathVariable Date dateTo` you need to change this to `@PathVariable Long dateTo` and the use `Date` constructor accepting the long epoch. – akortex Jun 27 '18 at 22:58
Thanks one thing you need to be wary of are timezone conversions for this. But I suppose as long as you don't have multiple clients from different timezones you should be fine. – akortex Jun 27 '18 at 23:02
As of now, it is the same timezon, but if in future, i receive requests from across different timezones, what should be the approach? – T Anna Jun 27 '18 at 23:13
I suggest you avoid the long outdated and notoriously troublesome `SimpleDateFormat` class. At least as the first option. And at least take some reservation. Today we have so much better in [`java.time`, the modern Java date and time API](https://docs.oracle.com/javase/tutorial/datetime/). – Ole V.V. Jun 28 '18 at 08:19
@OleV.V. parsing the date alltogether is not a good idea as mentioned in my original answer, using a timestamp is much more robust. The example using the SimpeDateFormat was meant to only show how the conversion from String to Date would happen. – akortex Jun 28 '18 at 08:30

Jim Garrison · Answer 3 · 2018-06-27T22:35:38.673

The value 1530137142067 is the number of milliseconds since the Unix epoch.

Example,

$ date
Wed, Jun 27, 2018  3:28:30 PM
$ date +%s
1530138468

The +%s option asks the date command to return the seconds since the epoch. If you format your value as 1530137142.067 you can see it's very close to what my system displayed.

This is probably the "best" (most portable) way to transmit a timestamp as a parameter, as long as both ends agree as to the timezone. The value returned by the date +%s command is in UTC. For maximum portability, you should use UTC everywhere and convert to the local timezone only on output. Internaly, everything should be UTC.

How to pass Java date as path variable in a rest get call

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