aboutsummaryrefslogtreecommitdiff
path: root/vendor/github.com/gorilla/schema/decoder.go
blob: 025e438b561a79a7c58d4f372b5df38cffa90261 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
// Copyright 2012 The Gorilla Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package schema

import (
	"encoding"
	"errors"
	"fmt"
	"reflect"
	"strings"
)

// NewDecoder returns a new Decoder.
func NewDecoder() *Decoder {
	return &Decoder{cache: newCache()}
}

// Decoder decodes values from a map[string][]string to a struct.
type Decoder struct {
	cache             *cache
	zeroEmpty         bool
	ignoreUnknownKeys bool
}

// SetAliasTag changes the tag used to locate custom field aliases.
// The default tag is "schema".
func (d *Decoder) SetAliasTag(tag string) {
	d.cache.tag = tag
}

// ZeroEmpty controls the behaviour when the decoder encounters empty values
// in a map.
// If z is true and a key in the map has the empty string as a value
// then the corresponding struct field is set to the zero value.
// If z is false then empty strings are ignored.
//
// The default value is false, that is empty values do not change
// the value of the struct field.
func (d *Decoder) ZeroEmpty(z bool) {
	d.zeroEmpty = z
}

// IgnoreUnknownKeys controls the behaviour when the decoder encounters unknown
// keys in the map.
// If i is true and an unknown field is encountered, it is ignored. This is
// similar to how unknown keys are handled by encoding/json.
// If i is false then Decode will return an error. Note that any valid keys
// will still be decoded in to the target struct.
//
// To preserve backwards compatibility, the default value is false.
func (d *Decoder) IgnoreUnknownKeys(i bool) {
	d.ignoreUnknownKeys = i
}

// RegisterConverter registers a converter function for a custom type.
func (d *Decoder) RegisterConverter(value interface{}, converterFunc Converter) {
	d.cache.registerConverter(value, converterFunc)
}

// Decode decodes a map[string][]string to a struct.
//
// The first parameter must be a pointer to a struct.
//
// The second parameter is a map, typically url.Values from an HTTP request.
// Keys are "paths" in dotted notation to the struct fields and nested structs.
//
// See the package documentation for a full explanation of the mechanics.
func (d *Decoder) Decode(dst interface{}, src map[string][]string) error {
	v := reflect.ValueOf(dst)
	if v.Kind() != reflect.Ptr || v.Elem().Kind() != reflect.Struct {
		return errors.New("schema: interface must be a pointer to struct")
	}
	v = v.Elem()
	t := v.Type()
	errors := MultiError{}
	for path, values := range src {
		if parts, err := d.cache.parsePath(path, t); err == nil {
			if err = d.decode(v, path, parts, values); err != nil {
				errors[path] = err
			}
		} else if !d.ignoreUnknownKeys {
			errors[path] = UnknownKeyError{Key: path}
		}
	}
	errors.merge(d.checkRequired(t, src))
	if len(errors) > 0 {
		return errors
	}
	return nil
}

// checkRequired checks whether required fields are empty
//
// check type t recursively if t has struct fields.
//
// src is the source map for decoding, we use it here to see if those required fields are included in src
func (d *Decoder) checkRequired(t reflect.Type, src map[string][]string) MultiError {
	m, errs := d.findRequiredFields(t, "", "")
	for key, fields := range m {
		if isEmptyFields(fields, src) {
			errs[key] = EmptyFieldError{Key: key}
		}
	}
	return errs
}

// findRequiredFields recursively searches the struct type t for required fields.
//
// canonicalPrefix and searchPrefix are used to resolve full paths in dotted notation
// for nested struct fields. canonicalPrefix is a complete path which never omits
// any embedded struct fields. searchPrefix is a user-friendly path which may omit
// some embedded struct fields to point promoted fields.
func (d *Decoder) findRequiredFields(t reflect.Type, canonicalPrefix, searchPrefix string) (map[string][]fieldWithPrefix, MultiError) {
	struc := d.cache.get(t)
	if struc == nil {
		// unexpect, cache.get never return nil
		return nil, MultiError{canonicalPrefix + "*": errors.New("cache fail")}
	}

	m := map[string][]fieldWithPrefix{}
	errs := MultiError{}
	for _, f := range struc.fields {
		if f.typ.Kind() == reflect.Struct {
			fcprefix := canonicalPrefix + f.canonicalAlias + "."
			for _, fspath := range f.paths(searchPrefix) {
				fm, ferrs := d.findRequiredFields(f.typ, fcprefix, fspath+".")
				for key, fields := range fm {
					m[key] = append(m[key], fields...)
				}
				errs.merge(ferrs)
			}
		}
		if f.isRequired {
			key := canonicalPrefix + f.canonicalAlias
			m[key] = append(m[key], fieldWithPrefix{
				fieldInfo: f,
				prefix:    searchPrefix,
			})
		}
	}
	return m, errs
}

type fieldWithPrefix struct {
	*fieldInfo
	prefix string
}

// isEmptyFields returns true if all of specified fields are empty.
func isEmptyFields(fields []fieldWithPrefix, src map[string][]string) bool {
	for _, f := range fields {
		for _, path := range f.paths(f.prefix) {
			v, ok := src[path]
			if ok && !isEmpty(f.typ, v) {
				return false
			}
			for key := range src {
				if !isEmpty(f.typ, src[key]) && strings.HasPrefix(key, path) {
					return false
				}
			}
		}
	}
	return true
}

// isEmpty returns true if value is empty for specific type
func isEmpty(t reflect.Type, value []string) bool {
	if len(value) == 0 {
		return true
	}
	switch t.Kind() {
	case boolType, float32Type, float64Type, intType, int8Type, int32Type, int64Type, stringType, uint8Type, uint16Type, uint32Type, uint64Type:
		return len(value[0]) == 0
	}
	return false
}

// decode fills a struct field using a parsed path.
func (d *Decoder) decode(v reflect.Value, path string, parts []pathPart, values []string) error {
	// Get the field walking the struct fields by index.
	for _, name := range parts[0].path {
		if v.Type().Kind() == reflect.Ptr {
			if v.IsNil() {
				v.Set(reflect.New(v.Type().Elem()))
			}
			v = v.Elem()
		}

		// alloc embedded structs
		if v.Type().Kind() == reflect.Struct {
			for i := 0; i < v.NumField(); i++ {
				field := v.Field(i)
				if field.Type().Kind() == reflect.Ptr && field.IsNil() && v.Type().Field(i).Anonymous == true {
					field.Set(reflect.New(field.Type().Elem()))
				}
			}
		}

		v = v.FieldByName(name)
	}
	// Don't even bother for unexported fields.
	if !v.CanSet() {
		return nil
	}

	// Dereference if needed.
	t := v.Type()
	if t.Kind() == reflect.Ptr {
		t = t.Elem()
		if v.IsNil() {
			v.Set(reflect.New(t))
		}
		v = v.Elem()
	}

	// Slice of structs. Let's go recursive.
	if len(parts) > 1 {
		idx := parts[0].index
		if v.IsNil() || v.Len() < idx+1 {
			value := reflect.MakeSlice(t, idx+1, idx+1)
			if v.Len() < idx+1 {
				// Resize it.
				reflect.Copy(value, v)
			}
			v.Set(value)
		}
		return d.decode(v.Index(idx), path, parts[1:], values)
	}

	// Get the converter early in case there is one for a slice type.
	conv := d.cache.converter(t)
	m := isTextUnmarshaler(v)
	if conv == nil && t.Kind() == reflect.Slice && m.IsSliceElement {
		var items []reflect.Value
		elemT := t.Elem()
		isPtrElem := elemT.Kind() == reflect.Ptr
		if isPtrElem {
			elemT = elemT.Elem()
		}

		// Try to get a converter for the element type.
		conv := d.cache.converter(elemT)
		if conv == nil {
			conv = builtinConverters[elemT.Kind()]
			if conv == nil {
				// As we are not dealing with slice of structs here, we don't need to check if the type
				// implements TextUnmarshaler interface
				return fmt.Errorf("schema: converter not found for %v", elemT)
			}
		}

		for key, value := range values {
			if value == "" {
				if d.zeroEmpty {
					items = append(items, reflect.Zero(elemT))
				}
			} else if m.IsValid {
				u := reflect.New(elemT)
				if m.IsSliceElementPtr {
					u = reflect.New(reflect.PtrTo(elemT).Elem())
				}
				if err := u.Interface().(encoding.TextUnmarshaler).UnmarshalText([]byte(value)); err != nil {
					return ConversionError{
						Key:   path,
						Type:  t,
						Index: key,
						Err:   err,
					}
				}
				if m.IsSliceElementPtr {
					items = append(items, u.Elem().Addr())
				} else if u.Kind() == reflect.Ptr {
					items = append(items, u.Elem())
				} else {
					items = append(items, u)
				}
			} else if item := conv(value); item.IsValid() {
				if isPtrElem {
					ptr := reflect.New(elemT)
					ptr.Elem().Set(item)
					item = ptr
				}
				if item.Type() != elemT && !isPtrElem {
					item = item.Convert(elemT)
				}
				items = append(items, item)
			} else {
				if strings.Contains(value, ",") {
					values := strings.Split(value, ",")
					for _, value := range values {
						if value == "" {
							if d.zeroEmpty {
								items = append(items, reflect.Zero(elemT))
							}
						} else if item := conv(value); item.IsValid() {
							if isPtrElem {
								ptr := reflect.New(elemT)
								ptr.Elem().Set(item)
								item = ptr
							}
							if item.Type() != elemT && !isPtrElem {
								item = item.Convert(elemT)
							}
							items = append(items, item)
						} else {
							return ConversionError{
								Key:   path,
								Type:  elemT,
								Index: key,
							}
						}
					}
				} else {
					return ConversionError{
						Key:   path,
						Type:  elemT,
						Index: key,
					}
				}
			}
		}
		value := reflect.Append(reflect.MakeSlice(t, 0, 0), items...)
		v.Set(value)
	} else {
		val := ""
		// Use the last value provided if any values were provided
		if len(values) > 0 {
			val = values[len(values)-1]
		}

		if conv != nil {
			if value := conv(val); value.IsValid() {
				v.Set(value.Convert(t))
			} else {
				return ConversionError{
					Key:   path,
					Type:  t,
					Index: -1,
				}
			}
		} else if m.IsValid {
			if m.IsPtr {
				u := reflect.New(v.Type())
				if err := u.Interface().(encoding.TextUnmarshaler).UnmarshalText([]byte(val)); err != nil {
					return ConversionError{
						Key:   path,
						Type:  t,
						Index: -1,
						Err:   err,
					}
				}
				v.Set(reflect.Indirect(u))
			} else {
				// If the value implements the encoding.TextUnmarshaler interface
				// apply UnmarshalText as the converter
				if err := m.Unmarshaler.UnmarshalText([]byte(val)); err != nil {
					return ConversionError{
						Key:   path,
						Type:  t,
						Index: -1,
						Err:   err,
					}
				}
			}
		} else if val == "" {
			if d.zeroEmpty {
				v.Set(reflect.Zero(t))
			}
		} else if conv := builtinConverters[t.Kind()]; conv != nil {
			if value := conv(val); value.IsValid() {
				v.Set(value.Convert(t))
			} else {
				return ConversionError{
					Key:   path,
					Type:  t,
					Index: -1,
				}
			}
		} else {
			return fmt.Errorf("schema: converter not found for %v", t)
		}
	}
	return nil
}

func isTextUnmarshaler(v reflect.Value) unmarshaler {
	// Create a new unmarshaller instance
	m := unmarshaler{}
	if m.Unmarshaler, m.IsValid = v.Interface().(encoding.TextUnmarshaler); m.IsValid {
		return m
	}
	// As the UnmarshalText function should be applied to the pointer of the
	// type, we check that type to see if it implements the necessary
	// method.
	if m.Unmarshaler, m.IsValid = reflect.New(v.Type()).Interface().(encoding.TextUnmarshaler); m.IsValid {
		m.IsPtr = true
		return m
	}

	// if v is []T or *[]T create new T
	t := v.Type()
	if t.Kind() == reflect.Ptr {
		t = t.Elem()
	}
	if t.Kind() == reflect.Slice {
		// Check if the slice implements encoding.TextUnmarshaller
		if m.Unmarshaler, m.IsValid = v.Interface().(encoding.TextUnmarshaler); m.IsValid {
			return m
		}
		// If t is a pointer slice, check if its elements implement
		// encoding.TextUnmarshaler
		m.IsSliceElement = true
		if t = t.Elem(); t.Kind() == reflect.Ptr {
			t = reflect.PtrTo(t.Elem())
			v = reflect.Zero(t)
			m.IsSliceElementPtr = true
			m.Unmarshaler, m.IsValid = v.Interface().(encoding.TextUnmarshaler)
			return m
		}
	}

	v = reflect.New(t)
	m.Unmarshaler, m.IsValid = v.Interface().(encoding.TextUnmarshaler)
	return m
}

// TextUnmarshaler helpers ----------------------------------------------------
// unmarshaller contains information about a TextUnmarshaler type
type unmarshaler struct {
	Unmarshaler encoding.TextUnmarshaler
	// IsValid indicates whether the resolved type indicated by the other
	// flags implements the encoding.TextUnmarshaler interface.
	IsValid bool
	// IsPtr indicates that the resolved type is the pointer of the original
	// type.
	IsPtr bool
	// IsSliceElement indicates that the resolved type is a slice element of
	// the original type.
	IsSliceElement bool
	// IsSliceElementPtr indicates that the resolved type is a pointer to a
	// slice element of the original type.
	IsSliceElementPtr bool
}

// Errors ---------------------------------------------------------------------

// ConversionError stores information about a failed conversion.
type ConversionError struct {
	Key   string       // key from the source map.
	Type  reflect.Type // expected type of elem
	Index int          // index for multi-value fields; -1 for single-value fields.
	Err   error        // low-level error (when it exists)
}

func (e ConversionError) Error() string {
	var output string

	if e.Index < 0 {
		output = fmt.Sprintf("schema: error converting value for %q", e.Key)
	} else {
		output = fmt.Sprintf("schema: error converting value for index %d of %q",
			e.Index, e.Key)
	}

	if e.Err != nil {
		output = fmt.Sprintf("%s. Details: %s", output, e.Err)
	}

	return output
}

// UnknownKeyError stores information about an unknown key in the source map.
type UnknownKeyError struct {
	Key string // key from the source map.
}

func (e UnknownKeyError) Error() string {
	return fmt.Sprintf("schema: invalid path %q", e.Key)
}

// EmptyFieldError stores information about an empty required field.
type EmptyFieldError struct {
	Key string // required key in the source map.
}

func (e EmptyFieldError) Error() string {
	return fmt.Sprintf("%v is empty", e.Key)
}

// MultiError stores multiple decoding errors.
//
// Borrowed from the App Engine SDK.
type MultiError map[string]error

func (e MultiError) Error() string {
	s := ""
	for _, err := range e {
		s = err.Error()
		break
	}
	switch len(e) {
	case 0:
		return "(0 errors)"
	case 1:
		return s
	case 2:
		return s + " (and 1 other error)"
	}
	return fmt.Sprintf("%s (and %d other errors)", s, len(e)-1)
}

func (e MultiError) merge(errors MultiError) {
	for key, err := range errors {
		if e[key] == nil {
			e[key] = err
		}
	}
}