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flatten.go
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flatten.go
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// Copyright (c) 2016 Jeremy Wohl
// Hacked together from sources obtained at https://github.com/jeremywohl/flatten
package flatten
import (
"errors"
"regexp"
"go.mongodb.org/mongo-driver/bson/primitive"
)
// The style of keys. If there is an input with two
// nested keys "f" and "g", with "f" at the root,
// { "f": { "g": ... } }
// the output will be the concatenation
// f{Middle}{Before}g{After}...
// Any struct element may be blank.
// If you use Middle, you will probably leave Before & After blank, and vice-versa.
// See examples in flatten_test.go and the "Default styles" here.
type SeparatorStyle struct {
Before string // Prepend to key
Middle string // Add between keys
After string // Append to key
}
// Default styles
var (
// Separate nested key components with dots, e.g. "a.b.1.c.d"
DotStyle = SeparatorStyle{Middle: "."}
// Separate with path-like slashes, e.g. a/b/1/c/d
PathStyle = SeparatorStyle{Middle: "/"}
// Separate ala Rails, e.g. "a[b][c][1][d]"
RailsStyle = SeparatorStyle{Before: "[", After: "]"}
// Separate with underscores, e.g. "a_b_1_c_d"
UnderscoreStyle = SeparatorStyle{Middle: "_"}
)
// Nested input must be a map or slice
var NotValidInputError = errors.New("Not a valid input: map or slice")
// Flatten generates a flat map from a nested one. The original may include values of type map, slice and scalar,
// but not struct. Keys in the flat map will be a compound of descending map keys and slice iterations.
// The presentation of keys is set by style. A prefix is joined to each key.
func Flatten(nested map[string]interface{}, style SeparatorStyle) (map[string]interface{}, error) {
flatmap := make(map[string]interface{})
err := flatten(true, flatmap, nested, "", style)
if err != nil {
return nil, err
}
return flatmap, nil
}
// JSON nested input must be a map
var NotValidJsonInputError = errors.New("Not a valid input, must be a map")
var isJsonMap = regexp.MustCompile(`^\s*\{`)
func flatten(top bool, flatMap map[string]interface{}, nested interface{}, prefix string, style SeparatorStyle) error {
assign := func(newKey string, v interface{}) error {
switch v.(type) {
case map[string]interface{}:
if err := flatten(false, flatMap, v, newKey, style); err != nil {
return err
}
case primitive.M:
if err := flatten(false, flatMap, v, newKey, style); err != nil {
return err
}
default:
flatMap[newKey] = v
}
return nil
}
switch nested.(type) {
case map[string]interface{}:
for k, v := range nested.(map[string]interface{}) {
newKey := enkey(top, prefix, k, style)
assign(newKey, v)
}
case primitive.M:
for k, v := range nested.(primitive.M) {
newKey := enkey(top, prefix, k, style)
assign(newKey, v)
}
default:
return NotValidInputError
}
return nil
}
func enkey(top bool, prefix, subkey string, style SeparatorStyle) string {
key := prefix
if top {
key += subkey
} else {
key += style.Before + style.Middle + subkey + style.After
}
return key
}