AWS EventBridge PutEvent Detail Malformed - amazon-web-services

Question

I have tried both AWS Go SDKs both versions and every time I get an error stating that the Details field is malformed. The Details field accepts a JSON string.
In SDK V2 you basically have a struct for the event
type Event struct {
Details []struct {
Key string `json:"Key"`
Value string `json:"Value"`
} `json:"Details"`
DetailType string `json:"DetailType"`
Source string `json:"Source"`
}
The example then builds up the JSON string with this code
myDetails := "{ "
for _, d := range event.Details {
myDetails = myDetails + "\"" + d.Key + "\": \"" + d.Value + "\","
}
myDetails = myDetails + " }"
And then make the api call
input := &cloudwatchevents.PutEventsInput{
Entries: []types.PutEventsRequestEntry{
{
Detail: &myDetails,
DetailType: &event.DetailType,
Resources: []string{
*lambdaARN,
},
Source: &event.Source,
},
},
}
Basically I get an error saying that the string assigned to the Detail field is malformed. I believe this is because the example code generates a string with a trailing which is not valid . However when you omit the , you get a nil memory reference.
AWS SDK Example
The example for SDK version 1 also generates an error.
Any help would be great

Answer 1

The code on the page you linked is not 100% correct. They actually link the "complete example" at the bottom of the page, which has slightly different code:
https://github.com/awsdocs/aws-doc-sdk-examples/blob/main/gov2/cloudwatch/PutEvent/PutEventv2.go#L108-L117
myDetails := "{ "
for i, d := range event.Details {
if i == (len(event.Details) - 1) {
myDetails = myDetails + "\"" + d.Key + "\": \"" + d.Value + "\""
} else {
myDetails = myDetails + "\"" + d.Key + "\": \"" + d.Value + "\","
}
}
myDetails = myDetails + " }"
But building the JSON like this is not ideal and error-prone, as you already found out.
I'd propose the following:
details := make(map[string]string, len(event.Details))
for _, d := range event.Details {
details[d.Key] = d.Value
}
b, err := json.Marshal(details)
if err != nil {
return
}
fmt.Println(string(b))
Checkout the playground to see it in action:
https://play.golang.com/p/E4ueZLGIKp4