Google Maps API and duration_in_traffic

Question

I am trying to understand DistanceMatrix API. When I do this on browser:

https://maps.googleapis.com/maps/api/distancematrix/json?origins=14.614786,121.046587&destinations=14.610301,121.080233&mode=driving&language=en&departure_time=now&key=MY_KEY

I get the duration_in_traffic.

{
   "destination_addresses" : [
      "17 Orchard Rd, Bagumbayan, Quezon City, 1109 Metro Manila, Philippines"
   ],
   "origin_addresses" : [ "74 C. Benitez St, Quezon City, Metro Manila, Philippines" ],
   "rows" : [
      {
         "elements" : [
            {
               "distance" : {
                  "text" : "8.5 km",
                  "value" : 8470
               },
               "duration" : {
                  "text" : "23 mins",
                  "value" : 1406
               },
               "duration_in_traffic" : {
                  "text" : "35 mins",
                  "value" : 2112
               },
               "status" : "OK"
            }
         ]
      }
   ],
   "status" : "OK"
}

But when I have it in golang using maps API

I do not get the duration_in_traffic and returns only null

    r := &maps.DistanceMatrixRequest{
    Language:      *language,
    DepartureTime: "now",
    ArrivalTime:   *arrivalTime,
}

Below is result

{
    "origin_addresses": [
        "74 C. Benitez St, Quezon City, Metro Manila, Philippines"
    ],
    "destination_addresses": [
        "17 Orchard Rd, Bagumbayan, Quezon City, 1109 Metro Manila, Philippines"
    ],
    "rows": [
        {
            "elements": [
                {
                    "status": "OK",
                    "distance": {
                        "text": "8.5 km",
                        "value": 8470
                    },
                    "duration": {
                        "value": 1406,
                        "text": "23m26s"
                    },
                    "duration_in_traffic": null
                }
            ]
        }
    ]
}

Anything I am doing wrong?

EDIT:

    r := &maps.DistanceMatrixRequest{
    Origins:       strings.Split(origins, "|"),
    Destinations:  strings.Split(destinations, "|"),
    Language:      "en",
    DepartureTime: "now",
    Mode:          maps.TravelModeDriving,
    Units:         maps.UnitsMetric,
}

resp, err := client.DistanceMatrix(context.Background(), r)
if err != nil {
    return c.JSON(http.StatusBadRequest, err)
}

return c.JSON(http.StatusOK, resp)

Answer 1

Another potential gotcha is that Google does not return duration_in_traffic if it has no traffic data.

Documentation states:

The duration in traffic is returned only if all of the following are true:

The request includes a departure_time parameter.
The request includes a valid API key, or a valid Google Maps Platform Premium Plan client ID and signature.
Traffic conditions are available for the requested route.
The mode parameter is set to driving.

Answer 2

Was running into the same issue as you, and the edit to your post solved my issue.

To clarify the solution for anyone who may come along later- the issue was that I wasn't specifying the DepartureTime in my request.

If you run the below code with DepartureTime commented-out, it prints:

go run traffic.go 
Duration in minutes: 0.000000

But with the DepartureTime: "now" specified in the request, it gives:

go run traffic.go 
Duration in minutes: 135.966667

Here's what the full working example looks like.

package main

import (
    "fmt"
    "log"

    "golang.org/x/net/context"
    "googlemaps.github.io/maps"
)

func main() {
    c, err := maps.NewClient(maps.WithAPIKey("my-api-key-here"))
    if err != nil {
        log.Fatalf("fatal error: %s", err)
    }
    r := &maps.DistanceMatrixRequest{
        Origins:      []string{"Newark, DE"},
        Destinations: []string{"Charles Town, WV"},
        Units:        maps.UnitsImperial,
        Language:     "en",
        // Must specify DepartureTime in order to get DurationInTraffic in response
        DepartureTime: "now",
    }
    route, err := c.DistanceMatrix(context.Background(), r)

    if err != nil {
        log.Fatalf("fatal error: %s", err)
    }

    fmt.Printf("Duration in minutes: %f\n", route.Rows[0].Elements[0].DurationInTraffic.Minutes())
}