-
Notifications
You must be signed in to change notification settings - Fork 0
/
fields.go
295 lines (251 loc) · 8.21 KB
/
fields.go
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
package configreader
import (
"encoding/base64"
"encoding/json"
"errors"
"fmt"
"reflect"
"github.com/mxmauro/configreader/internal/helpers"
"github.com/mxmauro/configreader/model"
)
// -----------------------------------------------------------------------------
func (cr *ConfigReader[T]) checkT() error {
var instT T
// Use reflection to inspect the configuration struct
rSettings := reflect.ValueOf(&instT).Elem()
if rSettings.Kind() != reflect.Struct {
return errors.New("template parameter must be a struct")
}
// Done
return nil
}
func (cr *ConfigReader[T]) fillFields(settings *T, values model.Values) error {
rSettings := reflect.ValueOf(settings).Elem()
return cr.fillFieldsRecursive(rSettings, values)
}
func (cr *ConfigReader[T]) fillFieldsRecursive(v reflect.Value, values model.Values) error {
// Ignore non-valid items
if !v.IsValid() {
return nil
}
// Ignore non-struct and pointers (single, double, ...) to non-structs
if !isStructOrPtrToStruct(v) {
return nil
}
// Allocate pointers if needed
v = ptrAlloc(v)
vType := v.Type()
// Populate each field
for fIdx := 0; fIdx < v.NumField(); fIdx++ {
field := v.Field(fIdx)
structField := vType.Field(fIdx)
// Analyze field tags
tags := structField.Tag
// Get our tag
configTag := tags.Get("config")
if len(configTag) == 0 {
// This field has no configuration but handle it if a struct or a pointer to one
effField := ptrAlloc(field)
if effField.Kind() == reflect.Struct {
// Create struct object
effField.Set(reflect.Zero(effField.Type()))
// Go deeper
err := cr.fillFieldsRecursive(effField, values)
if err != nil {
return err
}
}
// Jump to next field
continue
}
// Signal error if field cannot be written
if !field.CanSet() {
return fmt.Errorf("field \"%s.%s\" is not settable", vType.Name(), structField.Name)
}
// Get default value to use if no value is present
defaultValue, defaultValuePresent := tags.Lookup("default")
// Check if this field should be treated as JSON
isJson, isJsonPresent := helpers.Str2Bool(tags.Get("isjson"))
if !isJsonPresent {
isJson, isJsonPresent = helpers.Str2Bool(tags.Get("is_json"))
if !isJsonPresent {
isJson, isJsonPresent = helpers.Str2Bool(tags.Get("is-json"))
if !isJsonPresent {
isJson = false
}
}
}
// Get value to store
vToSet, vToSetIsPresent := values[configTag]
if !vToSetIsPresent {
if defaultValuePresent {
vToSet = defaultValue
} else {
vToSet = nil
}
}
// Get effective field
effField := ptrAlloc(field)
effFieldIsPtr := field.Kind() == reflect.Pointer
// Signal error if field cannot be written
if !effField.CanSet() {
return fmt.Errorf("field \"%s.%s\" is not settable", vType.Name(), structField.Name)
}
// Treat as JSON?
if !isJson {
switch effField.Kind() {
case reflect.String:
valueStr, isNil, ok := helpers.ToString(vToSet)
if !ok {
return fmt.Errorf("unable to convert value for field \"%s.%s\"", vType.Name(), structField.Name)
}
if isNil {
if !effFieldIsPtr {
return fmt.Errorf("unable to assign nil value to field \"%s.%s\"", vType.Name(), structField.Name)
}
effField.Set(reflect.Zero(effField.Type()))
} else {
effField.SetString(valueStr)
}
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
valueInt, isNil, overflow, ok := helpers.ToInt(vToSet, effField.Type().Bits())
if !ok {
return fmt.Errorf("unable to convert value for field \"%s.%s\"", vType.Name(), structField.Name)
}
if isNil {
if !effFieldIsPtr {
return fmt.Errorf("unable to assign nil value to field \"%s.%s\"", vType.Name(), structField.Name)
}
effField.Set(reflect.Zero(effField.Type()))
} else if overflow {
return fmt.Errorf("overflow while assigning value to field \"%s.%s\"", vType.Name(), structField.Name)
} else {
effField.SetInt(valueInt)
}
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
valueUint, isNil, overflow, ok := helpers.ToUint(vToSet, effField.Type().Bits())
if !ok {
return fmt.Errorf("unable to convert value for field \"%s.%s\"", vType.Name(), structField.Name)
}
if isNil {
if !effFieldIsPtr {
return fmt.Errorf("unable to assign nil value to field \"%s.%s\"", vType.Name(), structField.Name)
}
effField.Set(reflect.Zero(effField.Type()))
} else if overflow {
return fmt.Errorf("overflow while assigning value to field \"%s.%s\"", vType.Name(), structField.Name)
} else {
effField.SetUint(valueUint)
}
case reflect.Float32, reflect.Float64:
valueFloat, isNil, overflow, ok := helpers.ToFloat(vToSet)
if !ok {
return fmt.Errorf("unable to convert value for field \"%s.%s\"", vType.Name(), structField.Name)
}
if isNil {
if !effFieldIsPtr {
return fmt.Errorf("unable to assign nil value to field \"%s.%s\"", vType.Name(), structField.Name)
}
effField.Set(reflect.Zero(effField.Type()))
} else if overflow {
return fmt.Errorf("overflow while assigning value to field \"%s.%s\"", vType.Name(), structField.Name)
} else {
effField.SetFloat(valueFloat)
}
case reflect.Bool:
valueBool, isNil, ok := helpers.ToBool(vToSet)
if !ok {
return fmt.Errorf("unable to convert value for field \"%s.%s\"", vType.Name(), structField.Name)
}
if isNil {
if !effFieldIsPtr {
return fmt.Errorf("unable to assign nil value to field \"%s.%s\"", vType.Name(), structField.Name)
}
effField.Set(reflect.Zero(effField.Type()))
} else {
effField.SetBool(valueBool)
}
case reflect.Struct:
// Create struct object
effField.Set(reflect.Zero(effField.Type()))
// Go deeper
err := cr.fillFieldsRecursive(effField, values)
if err != nil {
return err
}
case reflect.Slice:
fallthrough
case reflect.Array:
if vToSet == nil {
if !effFieldIsPtr {
return fmt.Errorf("unable to assign nil value to field \"%s.%s\"", vType.Name(), structField.Name)
}
effField.Set(reflect.Zero(effField.Type()))
// DOne
break
}
// If the target a byte array/slice and the source a string, assume base64 encoded data
if effField.Elem().Kind() == reflect.Uint8 && reflect.TypeOf(vToSet).Kind() == reflect.String {
data, err := base64.StdEncoding.DecodeString(vToSet.(string))
if err != nil {
return fmt.Errorf("unable to convert value for field \"%s.%s\"", vType.Name(), structField.Name)
}
// Check array size or create slice
if effField.Kind() == reflect.Slice {
l := len(data)
effField.Set(reflect.MakeSlice(effField.Type(), l, l))
} else {
if len(data) != effField.Len() {
return fmt.Errorf("base64 encoded data length mismatch for field \"%s.%s\"", vType.Name(), structField.Name)
}
}
// Copy decoded data
copy(effField.Bytes(), data)
// Done
break
}
// No other conversion supported for now
return fmt.Errorf("unable to convert value for field \"%s.%s\"", vType.Name(), structField.Name)
default:
return fmt.Errorf("unable to convert value for field \"%s.%s\"", vType.Name(), structField.Name)
}
} else {
valueStr, isNil, ok := helpers.ToString(vToSet)
if !ok {
return fmt.Errorf("unable to convert value for json field \"%s.%s\"", vType.Name(), structField.Name)
}
if isNil {
if !effFieldIsPtr {
return fmt.Errorf("unable to assign nil value to json field \"%s.%s\"", vType.Name(), structField.Name)
}
effField.Set(reflect.Zero(effField.Type()))
} else {
iface := effField.Addr().Interface()
// Unmarshal
err := json.Unmarshal([]byte(valueStr), iface)
if err != nil {
return err
}
}
}
}
// Done
return nil
}
// -----------------------------------------------------------------------------
func ptrAlloc(v reflect.Value) reflect.Value {
for v.Kind() == reflect.Pointer {
if v.IsNil() {
v.Set(reflect.New(v.Type().Elem()))
}
v = v.Elem()
}
return v
}
func isStructOrPtrToStruct(v reflect.Value) bool {
vType := v.Type()
for vType.Kind() == reflect.Pointer {
vType = vType.Elem()
}
return vType.Kind() == reflect.Struct
}