json.go 9.3 KB

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  1. /*
  2. Copyright (c) 2012, Jason Moiron
  3. Permission is hereby granted, free of charge, to any person
  4. obtaining a copy of this software and associated documentation
  5. files (the "Software"), to deal in the Software without
  6. restriction, including without limitation the rights to use,
  7. copy, modify, merge, publish, distribute, sublicense, and/or sell
  8. copies of the Software, and to permit persons to whom the
  9. Software is furnished to do so, subject to the following
  10. conditions:
  11. The above copyright notice and this permission notice shall be
  12. included in all copies or substantial portions of the Software.
  13. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  14. EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
  15. OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  16. NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
  17. HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  18. WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  19. FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  20. OTHER DEALINGS IN THE SOFTWARE.
  21. // */
  22. // https://github.com/jmoiron/jsonq
  23. package myth
  24. import (
  25. "bytes"
  26. "encoding/json"
  27. "fmt"
  28. "strconv"
  29. )
  30. // JSONQuery is an object that enables querying of a Go map with a simple
  31. // positional query language.
  32. type JSONQuery struct {
  33. data map[string]interface{}
  34. }
  35. // NewJSONQuery creates a new JSONQuery obj from []byte.
  36. func NewJSONQuery(data []byte) *JSONQuery {
  37. obj := map[string]interface{}{}
  38. // bytes.NewReader(data) strings.NewReader(jsonstring)
  39. dec := json.NewDecoder(bytes.NewReader(data))
  40. dec.Decode(&obj)
  41. jq := new(JSONQuery)
  42. jq.data = obj
  43. return jq
  44. }
  45. // Bool extracts a bool the JSONQuery
  46. func (jq *JSONQuery) Bool(s ...string) (bool, error) {
  47. val, err := rquery(jq.data, s...)
  48. if err != nil {
  49. return false, err
  50. }
  51. return boolFromInterface(val)
  52. }
  53. // Float extracts a float from the JsonQuery
  54. func (jq *JSONQuery) Float(s ...string) (float64, error) {
  55. val, err := rquery(jq.data, s...)
  56. if err != nil {
  57. return 0.0, err
  58. }
  59. return floatFromInterface(val)
  60. }
  61. // Int extracts an int from the JsonQuery
  62. func (jq *JSONQuery) Int(s ...string) (int, error) {
  63. val, err := rquery(jq.data, s...)
  64. if err != nil {
  65. return 0, err
  66. }
  67. return intFromInterface(val)
  68. }
  69. // String extracts a string from the JsonQuery
  70. func (jq *JSONQuery) String(s ...string) (string, error) {
  71. val, err := rquery(jq.data, s...)
  72. if err != nil {
  73. return "", err
  74. }
  75. return stringFromInterface(val)
  76. }
  77. // Object extracts a json object from the JsonQuery
  78. func (jq *JSONQuery) Object(s ...string) (map[string]interface{}, error) {
  79. val, err := rquery(jq.data, s...)
  80. if err != nil {
  81. return map[string]interface{}{}, err
  82. }
  83. return objectFromInterface(val)
  84. }
  85. // Array extracts a []interface{} from the JsonQuery
  86. func (jq *JSONQuery) Array(s ...string) ([]interface{}, error) {
  87. val, err := rquery(jq.data, s...)
  88. if err != nil {
  89. return []interface{}{}, err
  90. }
  91. return arrayFromInterface(val)
  92. }
  93. // Interface extracts an interface{} from the JsonQuery
  94. func (jq *JSONQuery) Interface(s ...string) (interface{}, error) {
  95. val, err := rquery(jq.data, s...)
  96. if err != nil {
  97. return nil, err
  98. }
  99. return val, nil
  100. }
  101. // ArrayOfStrings extracts an array of strings from some json
  102. func (jq *JSONQuery) ArrayOfStrings(s ...string) ([]string, error) {
  103. array, err := jq.Array(s...)
  104. if err != nil {
  105. return []string{}, err
  106. }
  107. toReturn := make([]string, len(array))
  108. for index, val := range array {
  109. toReturn[index], err = stringFromInterface(val)
  110. if err != nil {
  111. return toReturn, err
  112. }
  113. }
  114. return toReturn, nil
  115. }
  116. // ArrayOfInts extracts an array of ints from some json
  117. func (jq *JSONQuery) ArrayOfInts(s ...string) ([]int, error) {
  118. array, err := jq.Array(s...)
  119. if err != nil {
  120. return []int{}, err
  121. }
  122. toReturn := make([]int, len(array))
  123. for index, val := range array {
  124. toReturn[index], err = intFromInterface(val)
  125. if err != nil {
  126. return toReturn, err
  127. }
  128. }
  129. return toReturn, nil
  130. }
  131. // ArrayOfFloats extracts an array of float64s from some json
  132. func (jq *JSONQuery) ArrayOfFloats(s ...string) ([]float64, error) {
  133. array, err := jq.Array(s...)
  134. if err != nil {
  135. return []float64{}, err
  136. }
  137. toReturn := make([]float64, len(array))
  138. for index, val := range array {
  139. toReturn[index], err = floatFromInterface(val)
  140. if err != nil {
  141. return toReturn, err
  142. }
  143. }
  144. return toReturn, nil
  145. }
  146. // ArrayOfBools extracts an array of bools from some json
  147. func (jq *JSONQuery) ArrayOfBools(s ...string) ([]bool, error) {
  148. array, err := jq.Array(s...)
  149. if err != nil {
  150. return []bool{}, err
  151. }
  152. toReturn := make([]bool, len(array))
  153. for index, val := range array {
  154. toReturn[index], err = boolFromInterface(val)
  155. if err != nil {
  156. return toReturn, err
  157. }
  158. }
  159. return toReturn, nil
  160. }
  161. // ArrayOfObjects extracts an array of map[string]interface{} (objects) from some json
  162. func (jq *JSONQuery) ArrayOfObjects(s ...string) ([]map[string]interface{}, error) {
  163. array, err := jq.Array(s...)
  164. if err != nil {
  165. return []map[string]interface{}{}, err
  166. }
  167. toReturn := make([]map[string]interface{}, len(array))
  168. for index, val := range array {
  169. toReturn[index], err = objectFromInterface(val)
  170. if err != nil {
  171. return toReturn, err
  172. }
  173. }
  174. return toReturn, nil
  175. }
  176. // ArrayOfArrays extracts an array of []interface{} (arrays) from some json
  177. func (jq *JSONQuery) ArrayOfArrays(s ...string) ([][]interface{}, error) {
  178. array, err := jq.Array(s...)
  179. if err != nil {
  180. return [][]interface{}{}, err
  181. }
  182. toReturn := make([][]interface{}, len(array))
  183. for index, val := range array {
  184. toReturn[index], err = arrayFromInterface(val)
  185. if err != nil {
  186. return toReturn, err
  187. }
  188. }
  189. return toReturn, nil
  190. }
  191. // Matrix2D is an alias for ArrayOfArrays
  192. func (jq *JSONQuery) Matrix2D(s ...string) ([][]interface{}, error) {
  193. return jq.ArrayOfArrays(s...)
  194. }
  195. // Recursively query a decoded json blob
  196. func rquery(blob interface{}, s ...string) (interface{}, error) {
  197. var (
  198. val interface{}
  199. err error
  200. )
  201. val = blob
  202. for _, q := range s {
  203. val, err = query(val, q)
  204. if err != nil {
  205. return nil, err
  206. }
  207. }
  208. switch val.(type) {
  209. case nil:
  210. return nil, fmt.Errorf("nil value")
  211. }
  212. return val, nil
  213. }
  214. // query a json blob for a single field or index. If query is a string, then
  215. // the blob is treated as a json object (map[string]interface{}). If query is
  216. // an integer, the blob is treated as a json array ([]interface{}). Any kind
  217. // of key or index error will result in a nil return value with an error set.
  218. func query(blob interface{}, query string) (interface{}, error) {
  219. index, err := strconv.Atoi(query)
  220. // if it's an integer, then we treat the current interface as an array
  221. if err == nil {
  222. switch blob.(type) {
  223. case []interface{}:
  224. default:
  225. return nil, fmt.Errorf("Array index on non-array")
  226. }
  227. if len(blob.([]interface{})) > index {
  228. return blob.([]interface{})[index], nil
  229. }
  230. return nil, fmt.Errorf("Array index %d out of bounds", index)
  231. }
  232. // blob is likely an object, but verify first
  233. switch blob.(type) {
  234. case map[string]interface{}:
  235. default:
  236. return nil, fmt.Errorf("Object lookup \"%s\" on non-object", query)
  237. }
  238. val, ok := blob.(map[string]interface{})[query]
  239. if !ok {
  240. return nil, fmt.Errorf("Object does not contain field %s", query)
  241. }
  242. return val, nil
  243. }
  244. // stringFromInterface converts an interface{} to a string and returns an error if types don't match.
  245. func stringFromInterface(val interface{}) (string, error) {
  246. switch val.(type) {
  247. case string:
  248. return val.(string), nil
  249. }
  250. return "", fmt.Errorf("Expected string value for String, got \"%v\"", val)
  251. }
  252. // boolFromInterface converts an interface{} to a bool and returns an error if types don't match.
  253. func boolFromInterface(val interface{}) (bool, error) {
  254. switch val.(type) {
  255. case bool:
  256. return val.(bool), nil
  257. }
  258. return false, fmt.Errorf("Expected boolean value for Bool, got \"%v\"", val)
  259. }
  260. // floatFromInterface converts an interface{} to a float64 and returns an error if types don't match.
  261. func floatFromInterface(val interface{}) (float64, error) {
  262. switch val.(type) {
  263. case float64:
  264. return val.(float64), nil
  265. case int:
  266. return float64(val.(int)), nil
  267. case string:
  268. fval, err := strconv.ParseFloat(val.(string), 64)
  269. if err == nil {
  270. return fval, nil
  271. }
  272. }
  273. return 0.0, fmt.Errorf("Expected numeric value for Float, got \"%v\"", val)
  274. }
  275. // intFromInterface converts an interface{} to an int and returns an error if types don't match.
  276. func intFromInterface(val interface{}) (int, error) {
  277. switch val.(type) {
  278. case float64:
  279. return int(val.(float64)), nil
  280. case string:
  281. ival, err := strconv.ParseFloat(val.(string), 64)
  282. if err == nil {
  283. return int(ival), nil
  284. }
  285. case int:
  286. return val.(int), nil
  287. }
  288. return 0, fmt.Errorf("Expected numeric value for Int, got \"%v\"", val)
  289. }
  290. // objectFromInterface converts an interface{} to a map[string]interface{} and returns an error if types don't match.
  291. func objectFromInterface(val interface{}) (map[string]interface{}, error) {
  292. switch val.(type) {
  293. case map[string]interface{}:
  294. return val.(map[string]interface{}), nil
  295. }
  296. return map[string]interface{}{}, fmt.Errorf("Expected json object for Object, got \"%v\"", val)
  297. }
  298. // arrayFromInterface converts an interface{} to an []interface{} and returns an error if types don't match.
  299. func arrayFromInterface(val interface{}) ([]interface{}, error) {
  300. switch val.(type) {
  301. case []interface{}:
  302. return val.([]interface{}), nil
  303. }
  304. return []interface{}{}, fmt.Errorf("Expected json array for Array, got \"%v\"", val)
  305. }