I am retrieving data from an API. The struct output is :
{
StreamSpecification: {
StreamEnabled: true,
StreamViewType: "NEW_AND_OLD_IMAGES"
},
TableStatus: "ACTIVE"
}
But if the API output does not have StreamSpecification in it, I am receiving the following error when trying to print the struct.
panic: runtime error: invalid memory address or nil pointer dereference [signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=xxxxxxxx]
How to check if the struct StreamSpecification exists in the value? Or how to fix the issue in any other way?
If I understand the question correctly, I would convert the struct into a map, and then check if the field you are interested in is in the map.
For example:
package main
import (
"encoding/json"
"fmt"
)
type MyStruct struct {
Name string
Score int
}
func main() {
ms := MyStruct{Name: "Amy", Score: 34}
var myMap map[string]interface{}
data, _ := json.Marshal(ms)
fmt.Println(data)
json.Unmarshal(data, &myMap)
fmt.Println(myMap)
_, ok := myMap["Name"]
fmt.Printf("name is in myMap: %t
", ok)
_, ok = myMap["Location"]
fmt.Printf("Location is in myMap: %t
", ok)
}
It sounds like you're trying to access StreamEnabled or StreamViewType when you haven't first confirmed if StreamSpecification was provided in the JSON object.
Assuming you have the internal StreamSpecification as a reference to a struct, you need to ensure that StreamSpecification isn't nil:
if (instance.StreamSpecification == nil) {
// StreamSpecification was not passed in the JSON.
}