Accessing custom fragments from child-additions

[k-butz]

Hi,

I'm having a Managed Object with two child-additions in my tenant. Both child-additions are having the same custom fragment (in this example hello).
In below minimal example I'm iterating through the child-additions and would like to access the custom fragment with help of mo.ManagedObject.Item.Get(). However, helloValue is always empty (even though the fragment definitely exists on the MO). Why would that be?

package main

import (
	"context"
	"fmt"

	"github.com/reubenmiller/go-c8y/pkg/c8y"
)

func main() {
	client := c8y.NewClientFromEnvironment(nil, false)

	mor, _, _ := client.Inventory.GetChildAdditions(context.Background(), "9261202",
		&c8y.ManagedObjectOptions{
			Query: "type eq myTest",
		})

	for _, mo := range mor.References {
		fmt.Println(mo.ManagedObject.ID)
		helloValue := mo.ManagedObject.Item.Get("hello")
		fmt.Println(helloValue)
	}
}

[reubenmiller]

This is one of the trickier parts that I haven't been able to solve nicely. Basically, when the response is an array of objects, the .Item property of an item in the array (e.g. the .ManagedObject in this case) does not have the raw JSON related to that items json array...so you can't access custom fields from it.

For most collections, the sdk adds a generic .Items which is an array of gjson objects, where gjson can be used to access any field using dot notation. Though the problem you ran into was that the managed object references structs, didn't have the .Items set, however I've just pushed a new version, v0.28.0 to fix this, and added a client example where I just took your example above and modified it slightly to show two different ways of accessing custom data from an array.

But in the future, if the returned object does not contain the information that you want, you can always fallback to using the response object (typically the second argument returned from any api calls), so you could of rewritten your example with (but the latest v0.28.0 release includes the .Items accessor, so check out the example):

func main() {
	client := c8y.NewClientFromEnvironment(nil, false)

	_, resp, err := client.Inventory.GetChildAdditions(context.Background(), "25636204",
		&c8y.ManagedObjectOptions{
			Query: "type eq myTest",
		})
	if err != nil {
		panic("request failed")
	}

	for _, mor := range resp.JSON("references").Array() {
		fmt.Printf("managedObject.id: %s\n", mor.Get("managedObject.id").String())

		if helloValue := mor.Get("managedObject.hello"); helloValue.Exists() {
			fmt.Printf("managedObject.hello: %s\n", helloValue)
		} else {
			fmt.Printf("managedObject.hello: <unset>\n")
		}
	}
}

[k-butz]

Excellent, can confirm it works well on v0.28! Also thanks for the hint about the response-fallback.