Map results in surprising key case

[evadnoob]

Map() results in a map with keys that are surprising. For example A struct with member CIDR, its resulting key in the map is cDIR. A member with Name results in a key with name, less surprising but still odd. It's like the Map() call is taking the inverse of the first character always. Is this by design? I think this behavior is in conflict with the documentation: "Keys are capitalized to find each corresponding exported field". The godoc is closer to the behavior.

import (
  "fmt"
  "testing"
)

type Record struct {
  Data    map[string]interface{}
  Mapping map[string]string
}

func StructToRecord(in interface{}) *Record {
  rec := Record{}
  rec.Data = make(map[string]interface{})
  rec.Mapping = make(map[string]string)
  typ := reflect.TypeOf(in)
  for i := 0; i < typ.NumField(); i++ {
    field := typ.Field(i)
    dbFieldName := field.Tag.Get("db")

    fmt.Printf("%d %v, tags: %v\n", i, field.Name, dbFieldName)
    if dbFieldName != "" {
      rec.Mapping[field.Name] = dbFieldName
    }
  }

  mergo.Map(&rec.Data, in)
  return &rec
}

func TestStructToRecord(t *testing.T) {

  type A struct {
    Name string `json:"name" db:"name"`
    CIDR string `json:"cidr" db:"cidr"`
  }

  type Record struct {
    Data    map[string]interface{}
    Mapping map[string]string
  }

  a := A{Name: "David", CIDR: "10.0.0.0/8"}
  rec := StructToRecord(a)
  fmt.Printf("rec: %+v\n", rec)
  if len(rec.Mapping) < 2 {
    t.Fatalf("struct to record failed, no mapping, struct missing tags?, rec: %+v, a: %+v ", rec, a)
  }
}

Output:

go test -v
=== RUN   TestStructToRecord
0 Name, tags: name
1 CIDR, tags: cidr
rec: &{Data:map[name:David cIDR:10.0.0.0/8] Mapping:map[Name:name CIDR:cidr]}
--- PASS: TestStructToRecord (0.00s)
PASS
ok             0.003s

[darccio]

Works in current master (future 0.3.10).