viper yaml config sequence

Question

I'm trying to read a yaml config file using viper (see viper docs). But I cannot see a way to read the sequence of map values under issue-types. I've tried the various Get_ methods but none seem to support this.

remote:
  host: http://localhost/
  user: admin
  password:  changeit

mapping:
    source-project-key: IT
    remote-project-key: SCRUM

issue-types:
  - source-type: Incident
    remote-type: Task
  - source-type: Service Request
    remote-type: Task
  - source-type: Change
    remote-type: Story
  - source-type: Problem
    remote-type: Task

I'd like to be able to iterate over the sequence of map[strings]

Answer 1

If you look closely at the different Get methods available, you'll see that the return types are string, []string, map[string]interface{}, map[string]string and map[string][]string.

However, the type of the value associated with "issue-types" is []map[string]string. So, the only way to get this data is through the Get method and using type assertions.

Now, the following code produces the appropriate type of issue_types, which is []map[string]string.

issues_types := make([]map[string]string, 0)
var m map[string]string

issues_i := viper.Get("issue-types")
// issues_i is interface{}

issues_s := issues_i.([]interface{})
// issues_s is []interface{}

for _, issue := range issues_s {
    // issue is an interface{}

    issue_map := issue.(map[interface{}]interface{})
    // issue_map is a map[interface{}]interface{}

    m = make(map[string]string)
    for k, v := range issue_map {
        m[k.(string)] = v.(string)
    }
    issues_types = append(issues_types, m)
}

fmt.Println(reflect.TypeOf(issues_types))
# []map[string]string

fmt.Println(issues_types)
# [map[source-type:Incident remote-type:Task]
#  map[source-type:Service Request remote-type:Task]
#  map[source-type:Change remote-type:Story]
#  map[source-type:Problem remote-type:Task]]

Note that I did not do any safety check in order to make the code smaller. However, the correct way of doing type assertion is:

var i interface{} = "42"
str, ok := i.(string)
if !ok {
    // A problem occurred, do something
}