When you call show()
method on a PaymentRequest
object, it returns the
payment request response. After the response is received, it must be sent back
to the retailer server. There, the transaction ID is verified against
PSP to ensure the transaction was successful. The UI is then updated for the
user based on the verification status.
To aid in verification, the response from Google Pay contains the fields required by NPCI. For more information, see the NPCI UPI Linking Specification . Additionally, Google Pay provides the flexibility of a customized response. Refer to Google Pay response section for detailed response fields.
The following example shows how the browser response is converted to a JSON string and sent back to the retailer server, then further processed. After receiving the server response, it will complete the payment by logging a message in the console.
/**
*
Process
the
response
from
browser
.
*
*
@
private
*
@
param
{
PaymentResponse
}
instrument
The
payment
instrument
that
was
authed
.
*/
function
processResponse
(
instrument
)
{
var
instrumentString
=
instrumentToJsonString
(
instrument
);
console
.
log
(
instrumentString
);
fetch
(
'/buy'
,
{
method
:
'POST'
,
headers
:
new
Headers
({
'Content-Type'
:
'application/json'
}),
body
:
instrumentString
,
})
.
then
(
function
(
buyResult
)
{
if
(
buyResult
.
ok
)
{
return
buyResult
.
json
();
}
console
.
log
(
'Error sending instrument to server.'
);
})
.
then
(
function
(
buyResultJson
)
{
completePayment
(
instrument
,
buyResultJson
.
status
,
buyResultJson
.
message
);
})
.
catch
(
function
(
err
)
{
console
.
log
(
'Unable to process payment. '
+
err
);
});
}
/**
*
Notify
browser
that
the
instrument
authorization
has
completed
.
*
*
@
private
*
@
param
{
PaymentResponse
}
instrument
The
payment
instrument
that
was
authed
.
*
@
param
{
string
}
result
Whether
the
auth
was
successful
.
Should
be
either
*
'success'
or
'fail'
.
*
@
param
{
string
}
msg
The
message
to
log
in
console
.
*/
function
completePayment
(
instrument
,
result
,
msg
)
{
instrument
.
complete
(
result
)
.
then
(
function
()
{
console
.
log
(
'Payment succeeds.'
);
console
.
log
(
msg
);
})
.
catch
(
function
(
err
)
{
console
.
log
(
err
);
});
}
Utility methods
This section will cover all of the utility methods used in the provided sample codes.
A utility method to show the alert dialog when the user cannot make payment with the Google Pay.
/**
Handle
Google
Pay
not
ready
to
pay
case
.
*/
function
handleNotReadyToPay
()
{
alert
(
'Google Pay is not ready to pay.'
);
}
Utility
method to convert paymentResponse
to JSON string.
*
Converts
the
payment
response
into
a
JSON
string
.
*
*
@
private
*
@
param
{
PaymentResponse
}
paymentResponse
The
payment
response
to
convert
.
*
@
return
{
string
}
The
string
representation
of
the
payment
response
.
*/
function
paymentResponseToJsonString
(
paymentResponse
)
{
//
PaymentResponse
is
an
interface
,
JSON
.
stringify
works
only
on
dictionaries
.
var
paymentResponseDictionary
=
{
methodName
:
paymentResponse
.
methodName
,
details
:
paymentResponse
.
details
,
shippingAddress
:
addressToJsonString
(
paymentResponse
.
shippingAddress
),
shippingOption
:
paymentResponse
.
shippingOption
,
payerName
:
paymentResponse
.
payerName
,
payerPhone
:
paymentResponse
.
payerPhone
,
payerEmail
:
paymentResponse
.
payerEmail
,
};
return
JSON
.
stringify
(
paymentResponseDictionary
,
undefined
,
2
);
}
