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
|
// +build example
package main
import (
"flag"
"fmt"
"os"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/aws/session"
"github.com/aws/aws-sdk-go/service/dynamodb"
"github.com/aws/aws-sdk-go/service/dynamodb/expression"
)
func exitWithError(err error) {
fmt.Fprintln(os.Stderr, err)
os.Exit(1)
}
func main() {
cfg := Config{}
if err := cfg.Load(); err != nil {
exitWithError(fmt.Errorf("failed to load config, %v", err))
}
// Create the config specifying the Region for the DynamoDB table.
// If Config.Region is not set the region must come from the shared
// config or AWS_REGION environment variable.
awscfg := &aws.Config{}
if len(cfg.Region) > 0 {
awscfg.WithRegion(cfg.Region)
}
// Create the session that the DynamoDB service will use.
sess := session.Must(session.NewSession(awscfg))
// Create the DynamoDB service client to make the query request with.
svc := dynamodb.New(sess)
// Create the Expression to fill the input struct with.
filt := expression.Name("Artist").Equal(expression.Value("No One You Know"))
proj := expression.NamesList(expression.Name("SongTitle"), expression.Name("AlbumTitle"))
expr, err := expression.NewBuilder().WithFilter(filt).WithProjection(proj).Build()
if err != nil {
exitWithError(fmt.Errorf("failed to create the Expression, %v", err))
}
// Build the query input parameters
params := &dynamodb.ScanInput{
ExpressionAttributeNames: expr.Names(),
ExpressionAttributeValues: expr.Values(),
FilterExpression: expr.Filter(),
ProjectionExpression: expr.Projection(),
TableName: aws.String(cfg.Table),
}
if cfg.Limit > 0 {
params.Limit = aws.Int64(cfg.Limit)
}
// Make the DynamoDB Query API call
result, err := svc.Scan(params)
if err != nil {
exitWithError(fmt.Errorf("failed to make Query API call, %v", err))
}
fmt.Println(result)
}
type Config struct {
Table string // required
Region string // optional
Limit int64 // optional
}
func (c *Config) Load() error {
flag.Int64Var(&c.Limit, "limit", 0, "Limit is the max items to be returned, 0 is no limit")
flag.StringVar(&c.Table, "table", "", "Table to Query on")
flag.StringVar(&c.Region, "region", "", "AWS Region the table is in")
flag.Parse()
if len(c.Table) == 0 {
flag.PrintDefaults()
return fmt.Errorf("table name is required.")
}
return nil
}
|
