PUT inventory custom fragment - cumulocity

Question

This is my device inventory with the custom tasks array:
{
...
"c8y_IsDevice": {},
"tasks": [
{
"task_status" : "NEW",
"task_id" : "1",
"task_data" : {
...
}
},
{
"task_status" : "DONE",
"task_id" : "2",
"task_data" : {
...
}
},
...
]
...
}
I want to create a MQTT/SMARTREST PUT template to update a task by id and status.
For example: 800,[task_id],[task_status]
I am not able to find a way for this, especially it's an json array and all my attempts end up in overwriting the complete json array.
Maybe there's sth. like a condition, if task_id = x -> set task_status = y
Thank you.

Answer 1

You can only replace the whole fragment. There is no way to partially modify fragments.

Answer 2

one way to do it is get the whole array, using it for create a new one locally with the changes to want to do and finally put it again into the database. It is not a kind of solution but have been working for me.

Answer 3

Thanks for the info, but I still got a question about updating an array.
Concerning your answers I want to update the whole fragment.
This is my inventory:
"tasks": [
{
"address": {
"street": "Street",
"street_number": "1"
},
"description": "Test Description",
"id": "1",
"status": "NEW"
},
{
"address": {
"street": "Street2",
"street_number": "2"
},
"description": "Test Description 2",
"id": "2",
"status": "DONE"
}
]
My template:
801,<$.tasks.status>,<$.tasks.description>,<$.tasks.address.street>,<$.tasks.address.street_number>
Template screenshot
Now I publish:
//801,SERIAL,status,description,street_name,street_nr
801,SERIAL,NEW,1,2,3,4
Of course, this will overwrite the array and just set a json object tasks.
"tasks": {
"address": {
"street": "2",
"street_number": "3"
},
"description": "1",
"status": "NEW"
}
So I tried tasks[*]/tasks[] in my template (like in response templates), but this won't work too. I don't get it, maybe you can give me a small solution about putting a complete fragment with an array inside.