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DynamoDBScanItems.go
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DynamoDBScanItems.go
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// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
// snippet-start:[dynamodb.go.scan_items]
package main
// snippet-start:[dynamodb.go.scan_items.imports]
import (
"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/dynamodbattribute"
"github.com/aws/aws-sdk-go/service/dynamodb/expression"
"fmt"
"log"
)
// snippet-end:[dynamodb.go.scan_items.imports]
// snippet-start:[dynamodb.go.scan_items.struct]
// Create struct to hold info about new item
type Item struct {
Year int
Title string
Plot string
Rating float64
}
// snippet-end:[dynamodb.go.scan_items.struct]
// Get the movies with a minimum rating of 4.0 in 2013
func main() {
// snippet-start:[dynamodb.go.scan_items.session]
// Initialize a session that the SDK will use to load
// credentials from the shared credentials file ~/.aws/credentials
// and region from the shared configuration file ~/.aws/config.
sess := session.Must(session.NewSessionWithOptions(session.Options{
SharedConfigState: session.SharedConfigEnable,
}))
// Create DynamoDB client
svc := dynamodb.New(sess)
// snippet-end:[dynamodb.go.scan_items.session]
// snippet-start:[dynamodb.go.scan_items.vars]
tableName := "Movies"
minRating := 4.0
year := 2013
// snippet-end:[dynamodb.go.scan_items.vars]
// snippet-start:[dynamodb.go.scan_items.expr]
// Create the Expression to fill the input struct with.
// Get all movies in that year; we'll pull out those with a higher rating later
filt := expression.Name("Year").Equal(expression.Value(year))
// Or we could get by ratings and pull out those with the right year later
// filt := expression.Name("info.rating").GreaterThan(expression.Value(min_rating))
// Get back the title, year, and rating
proj := expression.NamesList(expression.Name("Title"), expression.Name("Year"), expression.Name("Rating"))
expr, err := expression.NewBuilder().WithFilter(filt).WithProjection(proj).Build()
if err != nil {
log.Fatalf("Got error building expression: %s", err)
}
// snippet-end:[dynamodb.go.scan_items.expr]
// snippet-start:[dynamodb.go.scan_items.call]
// Build the query input parameters
params := &dynamodb.ScanInput{
ExpressionAttributeNames: expr.Names(),
ExpressionAttributeValues: expr.Values(),
FilterExpression: expr.Filter(),
ProjectionExpression: expr.Projection(),
TableName: aws.String(tableName),
}
// Make the DynamoDB Query API call
result, err := svc.Scan(params)
if err != nil {
log.Fatalf("Query API call failed: %s", err)
}
// snippet-end:[dynamodb.go.scan_items.call]
// snippet-start:[dynamodb.go.scan_items.process]
numItems := 0
for _, i := range result.Items {
item := Item{}
err = dynamodbattribute.UnmarshalMap(i, &item)
if err != nil {
log.Fatalf("Got error unmarshalling: %s", err)
}
// Which ones had a higher rating than minimum?
if item.Rating > minRating {
// Or it we had filtered by rating previously:
// if item.Year == year {
numItems++
fmt.Println("Title: ", item.Title)
fmt.Println("Rating:", item.Rating)
fmt.Println()
}
}
fmt.Println("Found", numItems, "movie(s) with a rating above", minRating, "in", year)
// snippet-end:[dynamodb.go.scan_items.process]
}
// snippet-end:[dynamodb.go.scan_items]