pass data from one Struct to another Struct and convert to json - go

Question

Hi I have json data which I Unmarshal to machines slice . Now I am looking to copy/append each cluster information, hostname from machines slice struct to Cluster Struct []Cluster and try to populate different values in that struct.
Each machine record has an associated serviceName . I am Looking for the out json format in the desired output below where service_name ,required, vars, value are only passed once even though they are associated with each json record when passed from machine slice.
current Code :
https://go.dev/play/p/6zVRIaLIgdN
Desired output :
{
"cluster_name": "dev",
"services": [
{
"service_name": "serviceA",
"required" : true,
"vars": {
"common_vars": {
"user": "custom-user",
"group": "custom-group"
}
},
"hosts": [
{
"host_name": "host1",
"vars": {
"common_vars" :{
"id": 1
}
}
},
{
"host_name": "host2",
"vars": {
"common_vars":{
"id": 2
}
}
}
]
},
{
"service_name": "serviceB",
"required" : false
.....
}
}
]
}
Current OutPut:
where the ServiceName is repeated with every machine name , I want it to have service_name once in the slice as above output
"cluster_name": "dev",
"services": [
{
"service_name": "serviceA",
"required": true,
"hosts": [
{
"host_name": "Machine-1",
"vars": {
"common_vars": {
"id": "1"
},
"custom_listeners": {}
}
}
],
"vars": {
"custom_listeners": {}
}
},
{
**"service_name": "serviceA"**,
"required": true,
"hosts": [
{
"host_name": "Machine-2",
"vars": {
"common_vars": {
"id": "2"
},
"custom_listeners": {}
}
}
],
"vars": {
"custom_listeners": {}
}
}
]
}

Answer 1

You have to implement some logic for merging service records with same name.
map[<ServiceName>]<Service> could be used to avoid iterating through slice of services every time.
m := map[string]*Service{}
for i := range machines {
s, found := m[machines[i].Servicename]
if !found {
s = &Service{ServiceName: machines[i].Servicename, Required: true}
m[machines[i].Servicename] = s
}
s.Hosts = append(s.Hosts, Host{HostName: machines[i].Hostname, Vars: Var{CommonVars: map[string]interface{}{"id": machines[i].ID}}})
}
for _, s := range m {
cService.Services = append(cService.Services, *s)
}