/
middleware_data.go
300 lines (225 loc) · 7.82 KB
/
middleware_data.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
296
297
298
299
300
package turtleware
import (
"github.com/jmoiron/sqlx"
"github.com/rs/zerolog"
"context"
"database/sql"
"errors"
"fmt"
"io"
"net/http"
"os"
)
type ListStaticDataFunc[T any] func(ctx context.Context, paging Paging) ([]T, error)
type ListSQLDataFunc func(ctx context.Context, paging Paging) (*sql.Rows, error)
type ListSQLxDataFunc func(ctx context.Context, paging Paging) (*sqlx.Rows, error)
type ResourceDataFunc[T any] func(ctx context.Context, entityUUID string) (T, error)
type SQLResourceFunc[T any] func(ctx context.Context, r *sql.Rows) (T, error)
type SQLxResourceFunc[T any] func(ctx context.Context, r *sqlx.Rows) (T, error)
func StaticListDataHandler[T any](dataFetcher ListStaticDataFunc[T], errorHandler ErrorHandlerFunc) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
logger := zerolog.Ctx(r.Context())
// Only proceed if we are working with an actual request
if r.Method == http.MethodHead {
logger.Trace().Msgf("Bailing out of list request because of HEAD method")
return
}
dataContext, cancel := context.WithCancel(r.Context())
defer cancel()
paging, err := PagingFromRequestContext(dataContext)
if err != nil {
errorHandler(dataContext, w, r, err)
return
}
logger.Trace().Msgf("Handling request for resource list request")
rows, err := dataFetcher(dataContext, paging)
if err != nil {
logger.Error().Err(err).Msg("Error while receiving rows")
errorHandler(dataContext, w, r, ErrReceivingResults)
return
}
if rows == nil {
rows = make([]T, 0)
}
logger.Trace().Msg("Assembling response for resource list request")
EmissioneWriter.Write(w, r, http.StatusOK, rows)
})
}
func SQLListDataHandler[T any](dataFetcher ListSQLDataFunc, dataTransformer SQLResourceFunc[T], errorHandler ErrorHandlerFunc) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
logger := zerolog.Ctx(r.Context())
// Only proceed if we are working with an actual request
if r.Method == http.MethodHead {
logger.Trace().Msg("Bailing out of list request because of HEAD method")
return
}
dataContext, cancel := context.WithCancel(r.Context())
defer cancel()
paging, err := PagingFromRequestContext(dataContext)
if err != nil {
errorHandler(dataContext, w, r, err)
return
}
rows, err := dataFetcher(dataContext, paging)
if err != nil {
logger.Error().Err(err).Msg("Error while receiving rows")
errorHandler(dataContext, w, r, ErrReceivingResults)
return
}
// Ensure row close, even on error
defer func() {
if err := rows.Close(); err != nil {
logger.Warn().Err(err).Msg("Failed to close row scanner")
}
}()
results, err := bufferSQLResults(dataContext, rows, dataTransformer)
if err != nil {
errorHandler(dataContext, w, r, ErrReceivingResults)
return
}
EmissioneWriter.Write(w, r, http.StatusOK, results)
})
}
func bufferSQLResults[T any](ctx context.Context, rows *sql.Rows, dataTransformer SQLResourceFunc[T]) ([]T, error) {
dataContext, cancel := context.WithCancel(ctx)
defer cancel()
logger := zerolog.Ctx(dataContext)
results := make([]T, 0)
for rows.Next() {
tempEntity, err := dataTransformer(dataContext, rows)
if err != nil {
logger.Error().Err(err).Msg("Error while receiving results")
return nil, ErrReceivingResults
}
results = append(results, tempEntity)
}
// Log, but don't act on the error
if err := rows.Err(); err != nil {
logger.Error().Err(err).Msg("Error while receiving results")
}
return results, nil
}
func SQLxListDataHandler[T any](dataFetcher ListSQLxDataFunc, dataTransformer SQLxResourceFunc[T], errorHandler ErrorHandlerFunc) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
logger := zerolog.Ctx(r.Context())
// Only proceed if we are working with an actual request
if r.Method == http.MethodHead {
logger.Trace().Msg("Bailing out of list request because of HEAD method")
return
}
dataContext, cancel := context.WithCancel(r.Context())
defer cancel()
paging, err := PagingFromRequestContext(dataContext)
if err != nil {
errorHandler(dataContext, w, r, err)
return
}
rows, err := dataFetcher(dataContext, paging)
if err != nil {
logger.Error().Err(err).Msg("Error while receiving rows")
errorHandler(dataContext, w, r, ErrReceivingResults)
return
}
// Ensure row close, even on error
defer func() {
if err := rows.Close(); err != nil {
logger.Warn().Err(err).Msg("Failed to close row scanner")
}
}()
results, err := bufferSQLxResults(dataContext, rows, dataTransformer)
if err != nil {
errorHandler(dataContext, w, r, ErrReceivingResults)
return
}
EmissioneWriter.Write(w, r, http.StatusOK, results)
})
}
func bufferSQLxResults[T any](ctx context.Context, rows *sqlx.Rows, dataTransformer SQLxResourceFunc[T]) ([]T, error) {
dataContext, cancel := context.WithCancel(ctx)
defer cancel()
logger := zerolog.Ctx(dataContext)
results := make([]T, 0)
for rows.Next() {
tempEntity, err := dataTransformer(dataContext, rows)
if err != nil {
logger.Error().Err(err).Msg("Error while receiving results")
return nil, ErrReceivingResults
}
results = append(results, tempEntity)
}
// Log, but don't act on the error
if err := rows.Err(); err != nil {
logger.Error().Err(err).Msg("Error while receiving results")
}
return results, nil
}
func ResourceDataHandler[T any](dataFetcher ResourceDataFunc[T], errorHandler ErrorHandlerFunc) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
logger := zerolog.Ctx(r.Context())
// Only proceed if we are working with an actual request
if r.Method == http.MethodHead {
logger.Trace().Msg("Bailing out of resource request because of HEAD method")
return
}
dataContext, cancel := context.WithCancel(r.Context())
defer cancel()
entityUUID, err := EntityUUIDFromRequestContext(dataContext)
if err != nil {
errorHandler(dataContext, w, r, err)
return
}
tempEntity, err := dataFetcher(dataContext, entityUUID)
if errors.Is(err, sql.ErrNoRows) || errors.Is(err, os.ErrNotExist) {
errorHandler(dataContext, w, r, ErrResourceNotFound)
return
}
if err != nil {
logger.Error().Err(err).Msg("Error while receiving results")
errorHandler(dataContext, w, r, ErrReceivingResults)
return
}
if reader, ok := any(tempEntity).(io.Reader); ok {
logger.Trace().Msg("Streaming response for resource request")
StreamResponse(reader, w, r, errorHandler)
} else {
logger.Trace().Msg("Assembling response for resource request")
EmissioneWriter.Write(w, r, http.StatusOK, tempEntity)
}
})
}
func StreamResponse(reader io.Reader, w http.ResponseWriter, r *http.Request, errorHandler ErrorHandlerFunc) {
logger := zerolog.Ctx(r.Context())
if readCloser, ok := reader.(io.ReadCloser); ok {
defer func() {
if err := readCloser.Close(); err != nil {
logger.Error().Err(err).Msg("Error closing reader")
}
}()
}
// Only the first 512 bytes are used to sniff the content type.
buffer := make([]byte, 512)
headerRead, err := reader.Read(buffer)
if err != nil {
errorHandler(
r.Context(),
w, r,
fmt.Errorf("error while trying to read content type: %w", err),
)
return
}
w.Header().Set("Content-Type", http.DetectContentType(buffer))
w.WriteHeader(http.StatusOK)
if _, err := w.Write(buffer[:headerRead]); err != nil {
// Worst-case - we already send the header and potentially
// some content, but something went wrong in between.
logger.Error().Err(err).Msg("Fatal error while streaming data")
return
}
// Copy all that is left in the pipe
if _, err := io.Copy(w, reader); err != nil {
// Worst-case - we already send the header and potentially
// some content, but something went wrong in between.
logger.Error().Err(err).Msg("Fatal error while streaming data")
return
}
}