85 lines
3.0 KiB
Go
85 lines
3.0 KiB
Go
// AttributeValue Marshaling and Unmarshaling Helpers
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//
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// Utility helpers to marshal and unmarshal AttributeValue to and
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// from Go types can be found in the dynamodbattribute sub package. This package
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// provides has specialized functions for the common ways of working with
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// AttributeValues. Such as map[string]*AttributeValue, []*AttributeValue, and
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// directly with *AttributeValue. This is helpful for marshaling Go types for API
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// operations such as PutItem, and unmarshaling Query and Scan APIs' responses.
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//
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// See the dynamodbattribute package documentation for more information.
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// https://docs.aws.amazon.com/sdk-for-go/api/service/dynamodb/dynamodbattribute/
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//
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// AttributeValue Marshaling
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//
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// To marshal a Go type to an AttributeValue you can use the Marshal
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// functions in the dynamodbattribute package. There are specialized versions
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// of these functions for collections of AttributeValue, such as maps and lists.
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//
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// The following example uses MarshalMap to convert the Record Go type to a
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// dynamodb.AttributeValue type and use the value to make a PutItem API request.
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//
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// type Record struct {
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// ID string
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// URLs []string
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// }
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//
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// //...
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//
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// r := Record{
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// ID: "ABC123",
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// URLs: []string{
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// "https://example.com/first/link",
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// "https://example.com/second/url",
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// },
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// }
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// av, err := dynamodbattribute.MarshalMap(r)
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// if err != nil {
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// panic(fmt.Sprintf("failed to DynamoDB marshal Record, %v", err))
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// }
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//
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// _, err = svc.PutItem(&dynamodb.PutItemInput{
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// TableName: aws.String(myTableName),
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// Item: av,
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// })
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// if err != nil {
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// panic(fmt.Sprintf("failed to put Record to DynamoDB, %v", err))
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// }
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//
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// AttributeValue Unmarshaling
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//
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// To unmarshal a dynamodb.AttributeValue to a Go type you can use the Unmarshal
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// functions in the dynamodbattribute package. There are specialized versions
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// of these functions for collections of AttributeValue, such as maps and lists.
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//
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// The following example will unmarshal the DynamoDB's Scan API operation. The
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// Items returned by the operation will be unmarshaled into the slice of Records
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// Go type.
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//
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// type Record struct {
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// ID string
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// URLs []string
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// }
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//
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// //...
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//
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// var records []Record
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//
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// // Use the ScanPages method to perform the scan with pagination. Use
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// // just Scan method to make the API call without pagination.
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// err := svc.ScanPages(&dynamodb.ScanInput{
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// TableName: aws.String(myTableName),
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// }, func(page *dynamodb.ScanOutput, last bool) bool {
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// recs := []Record{}
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//
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// err := dynamodbattribute.UnmarshalListOfMaps(page.Items, &recs)
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// if err != nil {
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// panic(fmt.Sprintf("failed to unmarshal Dynamodb Scan Items, %v", err))
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// }
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//
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// records = append(records, recs...)
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//
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// return true // keep paging
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// })
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package dynamodb
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