ScanÚselo con un AWS SDK o CLI

        public static async Task<int> ScanTableAsync(
            AmazonDynamoDBClient client,
            string tableName,
            int startYear,
            int endYear)
        {
            var request = new ScanRequest
            {
                TableName = tableName,
                ExpressionAttributeNames = new Dictionary<string, string>
                {
                  { "#yr", "year" },
                },
                ExpressionAttributeValues = new Dictionary<string, AttributeValue>
                {
                    { ":y_a", new AttributeValue { N = startYear.ToString() } },
                    { ":y_z", new AttributeValue { N = endYear.ToString() } },
                },
                FilterExpression = "#yr between :y_a and :y_z",
                ProjectionExpression = "#yr, title, info.actors[0], info.directors, info.running_time_secs",
                Limit = 10 // Set a limit to demonstrate using the LastEvaluatedKey.
            };

            // Keep track of how many movies were found.
            int foundCount = 0;

            var response = new ScanResponse();
            do
            {
                response = await client.ScanAsync(request);
                foundCount += response.Items.Count;
                response.Items.ForEach(i => DisplayItem(i));
                request.ExclusiveStartKey = response.LastEvaluatedKey;
            }
            while (response.LastEvaluatedKey.Count > 0);
            return foundCount;
        }

#############################################################################
# function dynamodb_scan
#
# This function scans a DynamoDB table.
#
# Parameters:
#       -n table_name  -- The name of the table.
#       -f filter_expression  -- The filter expression.
#       -a expression_attribute_names -- Path to JSON file containing the expression attribute names.
#       -v expression_attribute_values -- Path to JSON file containing the expression attribute values.
#       [-p projection_expression]  -- Optional projection expression.
#
#  Returns:
#       The items as json output.
#  And:
#       0 - If successful.
#       1 - If it fails.
###########################################################################
function dynamodb_scan() {
  local table_name filter_expression expression_attribute_names expression_attribute_values projection_expression response
  local option OPTARG # Required to use getopts command in a function.

  # ######################################
  # Function usage explanation
  #######################################
  function usage() {
    echo "function dynamodb_scan"
    echo "Scan a DynamoDB table."
    echo " -n table_name  -- The name of the table."
    echo " -f filter_expression  -- The filter expression."
    echo " -a expression_attribute_names -- Path to JSON file containing the expression attribute names."
    echo " -v expression_attribute_values -- Path to JSON file containing the expression attribute values."
    echo " [-p projection_expression]  -- Optional projection expression."
    echo ""
  }

  while getopts "n:f:a:v:p:h" option; do
    case "${option}" in
      n) table_name="${OPTARG}" ;;
      f) filter_expression="${OPTARG}" ;;
      a) expression_attribute_names="${OPTARG}" ;;
      v) expression_attribute_values="${OPTARG}" ;;
      p) projection_expression="${OPTARG}" ;;
      h)
        usage
        return 0
        ;;
      \?)
        echo "Invalid parameter"
        usage
        return 1
        ;;
    esac
  done
  export OPTIND=1

  if [[ -z "$table_name" ]]; then
    errecho "ERROR: You must provide a table name with the -n parameter."
    usage
    return 1
  fi

  if [[ -z "$filter_expression" ]]; then
    errecho "ERROR: You must provide a filter expression with the -f parameter."
    usage
    return 1
  fi

  if [[ -z "$expression_attribute_names" ]]; then
    errecho "ERROR: You must provide expression attribute names with the -a parameter."
    usage
    return 1
  fi

  if [[ -z "$expression_attribute_values" ]]; then
    errecho "ERROR: You must provide expression attribute values with the -v parameter."
    usage
    return 1
  fi

  if [[ -z "$projection_expression" ]]; then
    response=$(aws dynamodb scan \
      --table-name "$table_name" \
      --filter-expression "$filter_expression" \
      --expression-attribute-names file://"$expression_attribute_names" \
      --expression-attribute-values file://"$expression_attribute_values")
  else
    response=$(aws dynamodb scan \
      --table-name "$table_name" \
      --filter-expression "$filter_expression" \
      --expression-attribute-names file://"$expression_attribute_names" \
      --expression-attribute-values file://"$expression_attribute_values" \
      --projection-expression "$projection_expression")
  fi

  local error_code=${?}

  if [[ $error_code -ne 0 ]]; then
    aws_cli_error_log $error_code
    errecho "ERROR: AWS reports scan operation failed.$response"
    return 1
  fi

  echo "$response"

  return 0
}

Las funciones de utilidad utilizadas en este ejemplo.

###############################################################################
# function errecho
#
# This function outputs everything sent to it to STDERR (standard error output).
###############################################################################
function errecho() {
  printf "%s\n" "$*" 1>&2
}

##############################################################################
# function aws_cli_error_log()
#
# This function is used to log the error messages from the AWS CLI.
#
# See https://docs.aws.amazon.com/cli/latest/topic/return-codes.html#cli-aws-help-return-codes.
#
# The function expects the following argument:
#         $1 - The error code returned by the AWS CLI.
#
#  Returns:
#          0: - Success.
#
##############################################################################
function aws_cli_error_log() {
  local err_code=$1
  errecho "Error code : $err_code"
  if [ "$err_code" == 1 ]; then
    errecho "  One or more S3 transfers failed."
  elif [ "$err_code" == 2 ]; then
    errecho "  Command line failed to parse."
  elif [ "$err_code" == 130 ]; then
    errecho "  Process received SIGINT."
  elif [ "$err_code" == 252 ]; then
    errecho "  Command syntax invalid."
  elif [ "$err_code" == 253 ]; then
    errecho "  The system environment or configuration was invalid."
  elif [ "$err_code" == 254 ]; then
    errecho "  The service returned an error."
  elif [ "$err_code" == 255 ]; then
    errecho "  255 is a catch-all error."
  fi

  return 0
}

//! Scan an Amazon DynamoDB table.
/*!
  \sa scanTable()
  \param tableName: Name for the DynamoDB table.
  \param projectionExpression: An optional projection expression, ignored if empty.
  \param clientConfiguration: AWS client configuration.
  \return bool: Function succeeded.
 */

bool AwsDoc::DynamoDB::scanTable(const Aws::String &tableName,
                                 const Aws::String &projectionExpression,
                                 const Aws::Client::ClientConfiguration &clientConfiguration) {
    Aws::DynamoDB::DynamoDBClient dynamoClient(clientConfiguration);
    Aws::DynamoDB::Model::ScanRequest request;
    request.SetTableName(tableName);

    if (!projectionExpression.empty())
        request.SetProjectionExpression(projectionExpression);

    Aws::Vector<Aws::Map<Aws::String, Aws::DynamoDB::Model::AttributeValue>> all_items;
    Aws::Map<Aws::String, Aws::DynamoDB::Model::AttributeValue> last_evaluated_key; // Used for pagination;
    do {
        if (!last_evaluated_key.empty()) {
            request.SetExclusiveStartKey(last_evaluated_key);
        }
        const Aws::DynamoDB::Model::ScanOutcome &outcome = dynamoClient.Scan(request);
        if (outcome.IsSuccess()) {
            // Reference the retrieved items.
            const Aws::Vector<Aws::Map<Aws::String, Aws::DynamoDB::Model::AttributeValue>> &items = outcome.GetResult().GetItems();
            all_items.insert(all_items.end(), items.begin(), items.end());

            last_evaluated_key = outcome.GetResult().GetLastEvaluatedKey();
        }
        else {
            std::cerr << "Failed to Scan items: " << outcome.GetError().GetMessage()
                      << std::endl;
            return false;
        }

    } while (!last_evaluated_key.empty());

    if (!all_items.empty()) {
        std::cout << "Number of items retrieved from scan: " << all_items.size()
                  << std::endl;
        // Iterate each item and print.
        for (const Aws::Map<Aws::String, Aws::DynamoDB::Model::AttributeValue> &itemMap: all_items) {
            std::cout << "******************************************************"
                      << std::endl;
            // Output each retrieved field and its value.
            for (const auto &itemEntry: itemMap)
                std::cout << itemEntry.first << ": " << itemEntry.second.GetS()
                          << std::endl;
        }
    }

    else {
        std::cout << "No items found in table: " << tableName << std::endl;
    }

    return true;
}

Análisis de una tabla

En el siguiente ejemplo de scan se escanea toda la tabla MusicCollection y, a continuación, se reducen los resultados a las canciones del artista “No One You Know”. Para cada elemento, solo se devuelven el título del álbum y el título de la canción.

aws dynamodb scan \
    --table-name MusicCollection \
    --filter-expression "Artist = :a" \
    --projection-expression "#ST, #AT" \
    --expression-attribute-names file://expression-attribute-names.json \
    --expression-attribute-values file://expression-attribute-values.json

Contenidos de expression-attribute-names.json:

{
    "#ST": "SongTitle",
    "#AT":"AlbumTitle"
}

Contenidos de expression-attribute-values.json:

{
    ":a": {"S": "No One You Know"}
}

Salida:

{
    "Count": 2,
    "Items": [
        {
            "SongTitle": {
                "S": "Call Me Today"
            },
            "AlbumTitle": {
                "S": "Somewhat Famous"
            }
        },
        {
            "SongTitle": {
                "S": "Scared of My Shadow"
            },
            "AlbumTitle": {
                "S": "Blue Sky Blues"
            }
        }
    ],
    "ScannedCount": 3,
    "ConsumedCapacity": null
}

Para obtener más información, consulte Uso de operaciones de análisis en DynamoDB en la Guía para desarrolladores de Amazon DynamoDB.

import (
	"context"
	"errors"
	"log"
	"time"

	"github.com/aws/aws-sdk-go-v2/aws"
	"github.com/aws/aws-sdk-go-v2/feature/dynamodb/attributevalue"
	"github.com/aws/aws-sdk-go-v2/feature/dynamodb/expression"
	"github.com/aws/aws-sdk-go-v2/service/dynamodb"
	"github.com/aws/aws-sdk-go-v2/service/dynamodb/types"
)

// TableBasics encapsulates the Amazon DynamoDB service actions used in the examples.
// It contains a DynamoDB service client that is used to act on the specified table.
type TableBasics struct {
	DynamoDbClient *dynamodb.Client
	TableName      string
}



// Scan gets all movies in the DynamoDB table that were released in a range of years
// and projects them to return a reduced set of fields.
// The function uses the `expression` package to build the filter and projection
// expressions.
func (basics TableBasics) Scan(ctx context.Context, startYear int, endYear int) ([]Movie, error) {
	var movies []Movie
	var err error
	var response *dynamodb.ScanOutput
	filtEx := expression.Name("year").Between(expression.Value(startYear), expression.Value(endYear))
	projEx := expression.NamesList(
		expression.Name("year"), expression.Name("title"), expression.Name("info.rating"))
	expr, err := expression.NewBuilder().WithFilter(filtEx).WithProjection(projEx).Build()
	if err != nil {
		log.Printf("Couldn't build expressions for scan. Here's why: %v\n", err)
	} else {
		scanPaginator := dynamodb.NewScanPaginator(basics.DynamoDbClient, &dynamodb.ScanInput{
			TableName:                 aws.String(basics.TableName),
			ExpressionAttributeNames:  expr.Names(),
			ExpressionAttributeValues: expr.Values(),
			FilterExpression:          expr.Filter(),
			ProjectionExpression:      expr.Projection(),
		})
		for scanPaginator.HasMorePages() {
			response, err = scanPaginator.NextPage(ctx)
			if err != nil {
				log.Printf("Couldn't scan for movies released between %v and %v. Here's why: %v\n",
					startYear, endYear, err)
				break
			} else {
				var moviePage []Movie
				err = attributevalue.UnmarshalListOfMaps(response.Items, &moviePage)
				if err != nil {
					log.Printf("Couldn't unmarshal query response. Here's why: %v\n", err)
					break
				} else {
					movies = append(movies, moviePage...)
				}
			}
		}
	}
	return movies, err
}

Defina una estructura Película para utilizar en este ejemplo.

import (
	"archive/zip"
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/http"

	"github.com/aws/aws-sdk-go-v2/feature/dynamodb/attributevalue"
	"github.com/aws/aws-sdk-go-v2/service/dynamodb/types"
)

// Movie encapsulates data about a movie. Title and Year are the composite primary key
// of the movie in Amazon DynamoDB. Title is the sort key, Year is the partition key,
// and Info is additional data.
type Movie struct {
	Title string                 `dynamodbav:"title"`
	Year  int                    `dynamodbav:"year"`
	Info  map[string]interface{} `dynamodbav:"info"`
}

// GetKey returns the composite primary key of the movie in a format that can be
// sent to DynamoDB.
func (movie Movie) GetKey() map[string]types.AttributeValue {
	title, err := attributevalue.Marshal(movie.Title)
	if err != nil {
		panic(err)
	}
	year, err := attributevalue.Marshal(movie.Year)
	if err != nil {
		panic(err)
	}
	return map[string]types.AttributeValue{"title": title, "year": year}
}

// String returns the title, year, rating, and plot of a movie, formatted for the example.
func (movie Movie) String() string {
	return fmt.Sprintf("%v\n\tReleased: %v\n\tRating: %v\n\tPlot: %v\n",
		movie.Title, movie.Year, movie.Info["rating"], movie.Info["plot"])
}

Escanea una tabla de Amazon DynamoDB utilizando. DynamoDbClient

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.ScanRequest;
import software.amazon.awssdk.services.dynamodb.model.ScanResponse;
import java.util.Map;
import java.util.Set;

/**
 * Before running this Java V2 code example, set up your development
 * environment, including your credentials.
 *
 * For more information, see the following documentation topic:
 *
 * https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html
 *
 * To scan items from an Amazon DynamoDB table using the AWS SDK for Java V2,
 * its better practice to use the
 * Enhanced Client, See the EnhancedScanRecords example.
 */

public class DynamoDBScanItems {
    public static void main(String[] args) {

        final String usage = """

                Usage:
                    <tableName>

                Where:
                    tableName - The Amazon DynamoDB table to get information from (for example, Music3).
                """;

        if (args.length != 1) {
            System.out.println(usage);
            System.exit(1);
        }

        String tableName = args[0];
        Region region = Region.US_EAST_1;
        DynamoDbClient ddb = DynamoDbClient.builder()
                .region(region)
                .build();

        scanItems(ddb, tableName);
        ddb.close();
    }

    public static void scanItems(DynamoDbClient ddb, String tableName) {
        try {
            ScanRequest scanRequest = ScanRequest.builder()
                    .tableName(tableName)
                    .build();

            ScanResponse response = ddb.scan(scanRequest);
            for (Map<String, AttributeValue> item : response.items()) {
                Set<String> keys = item.keySet();
                for (String key : keys) {
                    System.out.println("The key name is " + key + "\n");
                    System.out.println("The value is " + item.get(key).s());
                }
            }

        } catch (DynamoDbException e) {
            e.printStackTrace();
            System.exit(1);
        }
    }
}

Este ejemplo utiliza el cliente de documentos para simplificar el trabajo con elementos en DynamoDB. Para API obtener más información, consulte ScanCommand.

import { DynamoDBClient } from "@aws-sdk/client-dynamodb";
import { DynamoDBDocumentClient, ScanCommand } from "@aws-sdk/lib-dynamodb";

const client = new DynamoDBClient({});
const docClient = DynamoDBDocumentClient.from(client);

export const main = async () => {
  const command = new ScanCommand({
    ProjectionExpression: "#Name, Color, AvgLifeSpan",
    ExpressionAttributeNames: { "#Name": "Name" },
    TableName: "Birds",
  });

  const response = await docClient.send(command);
  for (const bird of response.Items) {
    console.log(`${bird.Name} - (${bird.Color}, ${bird.AvgLifeSpan})`);
  }
  return response;
};

// Load the AWS SDK for Node.js.
var AWS = require("aws-sdk");
// Set the AWS Region.
AWS.config.update({ region: "REGION" });

// Create DynamoDB service object.
var ddb = new AWS.DynamoDB({ apiVersion: "2012-08-10" });

const params = {
  // Specify which items in the results are returned.
  FilterExpression: "Subtitle = :topic AND Season = :s AND Episode = :e",
  // Define the expression attribute value, which are substitutes for the values you want to compare.
  ExpressionAttributeValues: {
    ":topic": { S: "SubTitle2" },
    ":s": { N: 1 },
    ":e": { N: 2 },
  },
  // Set the projection expression, which are the attributes that you want.
  ProjectionExpression: "Season, Episode, Title, Subtitle",
  TableName: "EPISODES_TABLE",
};

ddb.scan(params, function (err, data) {
  if (err) {
    console.log("Error", err);
  } else {
    console.log("Success", data);
    data.Items.forEach(function (element, index, array) {
      console.log(
        "printing",
        element.Title.S + " (" + element.Subtitle.S + ")"
      );
    });
  }
});

suspend fun scanItems(tableNameVal: String) {
    val request =
        ScanRequest {
            tableName = tableNameVal
        }

    DynamoDbClient { region = "us-east-1" }.use { ddb ->
        val response = ddb.scan(request)
        response.items?.forEach { item ->
            item.keys.forEach { key ->
                println("The key name is $key\n")
                println("The value is ${item[key]}")
            }
        }
    }
}

        $yearsKey = [
            'Key' => [
                'year' => [
                    'N' => [
                        'minRange' => 1990,
                        'maxRange' => 1999,
                    ],
                ],
            ],
        ];
        $filter = "year between 1990 and 1999";
        echo "\nHere's a list of all the movies released in the 90s:\n";
        $result = $service->scan($tableName, $yearsKey, $filter);
        foreach ($result['Items'] as $movie) {
            $movie = $marshal->unmarshalItem($movie);
            echo $movie['title'] . "\n";
        }

    public function scan(string $tableName, array $key, string $filters)
    {
        $query = [
            'ExpressionAttributeNames' => ['#year' => 'year'],
            'ExpressionAttributeValues' => [
                ":min" => ['N' => '1990'],
                ":max" => ['N' => '1999'],
            ],
            'FilterExpression' => "#year between :min and :max",
            'TableName' => $tableName,
        ];
        return $this->dynamoDbClient->scan($query);
    }

Ejemplo 1: devuelve todos los elementos de la tabla Music.

Invoke-DDBScan -TableName 'Music' | ConvertFrom-DDBItem

Salida:

Name                           Value
----                           -----
Genre                          Country
Artist                         No One You Know
Price                          1.94
CriticRating                   9
SongTitle                      Somewhere Down The Road
AlbumTitle                     Somewhat Famous
Genre                          Country
Artist                         No One You Know
Price                          1.98
CriticRating                   8.4
SongTitle                      My Dog Spot
AlbumTitle                     Hey Now

Ejemplo 2: Devuelve los elementos de la tabla Música con un valor CriticRating mayor o igual a nueve.

$scanFilter = @{
        CriticRating = [Amazon.DynamoDBv2.Model.Condition]@{
            AttributeValueList = @(@{N = '9'})
            ComparisonOperator = 'GE'
        }
    }
    Invoke-DDBScan -TableName 'Music' -ScanFilter $scanFilter | ConvertFrom-DDBItem

Salida:

Name                           Value
----                           -----
Genre                          Country
Artist                         No One You Know
Price                          1.94
CriticRating                   9
SongTitle                      Somewhere Down The Road
AlbumTitle                     Somewhat Famous

class Movies:
    """Encapsulates an Amazon DynamoDB table of movie data.

    Example data structure for a movie record in this table:
        {
            "year": 1999,
            "title": "For Love of the Game",
            "info": {
                "directors": ["Sam Raimi"],
                "release_date": "1999-09-15T00:00:00Z",
                "rating": 6.3,
                "plot": "A washed up pitcher flashes through his career.",
                "rank": 4987,
                "running_time_secs": 8220,
                "actors": [
                    "Kevin Costner",
                    "Kelly Preston",
                    "John C. Reilly"
                ]
            }
        }
    """

    def __init__(self, dyn_resource):
        """
        :param dyn_resource: A Boto3 DynamoDB resource.
        """
        self.dyn_resource = dyn_resource
        # The table variable is set during the scenario in the call to
        # 'exists' if the table exists. Otherwise, it is set by 'create_table'.
        self.table = None


    def scan_movies(self, year_range):
        """
        Scans for movies that were released in a range of years.
        Uses a projection expression to return a subset of data for each movie.

        :param year_range: The range of years to retrieve.
        :return: The list of movies released in the specified years.
        """
        movies = []
        scan_kwargs = {
            "FilterExpression": Key("year").between(
                year_range["first"], year_range["second"]
            ),
            "ProjectionExpression": "#yr, title, info.rating",
            "ExpressionAttributeNames": {"#yr": "year"},
        }
        try:
            done = False
            start_key = None
            while not done:
                if start_key:
                    scan_kwargs["ExclusiveStartKey"] = start_key
                response = self.table.scan(**scan_kwargs)
                movies.extend(response.get("Items", []))
                start_key = response.get("LastEvaluatedKey", None)
                done = start_key is None
        except ClientError as err:
            logger.error(
                "Couldn't scan for movies. Here's why: %s: %s",
                err.response["Error"]["Code"],
                err.response["Error"]["Message"],
            )
            raise

        return movies

class DynamoDBBasics
  attr_reader :dynamo_resource, :table

  def initialize(table_name)
    client = Aws::DynamoDB::Client.new(region: 'us-east-1')
    @dynamo_resource = Aws::DynamoDB::Resource.new(client: client)
    @table = @dynamo_resource.table(table_name)
  end

  # Scans for movies that were released in a range of years.
  # Uses a projection expression to return a subset of data for each movie.
  #
  # @param year_range [Hash] The range of years to retrieve.
  # @return [Array] The list of movies released in the specified years.
  def scan_items(year_range)
    movies = []
    scan_hash = {
      filter_expression: '#yr between :start_yr and :end_yr',
      projection_expression: '#yr, title, info.rating',
      expression_attribute_names: { '#yr' => 'year' },
      expression_attribute_values: {
        ':start_yr' => year_range[:start], ':end_yr' => year_range[:end]
      }
    }
    done = false
    start_key = nil
    until done
      scan_hash[:exclusive_start_key] = start_key unless start_key.nil?
      response = @table.scan(scan_hash)
      movies.concat(response.items) unless response.items.empty?
      start_key = response.last_evaluated_key
      done = start_key.nil?
    end
  rescue Aws::DynamoDB::Errors::ServiceError => e
    puts("Couldn't scan for movies. Here's why:")
    puts("\t#{e.code}: #{e.message}")
    raise
  else
    movies
  end

pub async fn list_items(client: &Client, table: &str, page_size: Option<i32>) -> Result<(), Error> {
    let page_size = page_size.unwrap_or(10);
    let items: Result<Vec<_>, _> = client
        .scan()
        .table_name(table)
        .limit(page_size)
        .into_paginator()
        .items()
        .send()
        .collect()
        .await;

    println!("Items in table (up to {page_size}):");
    for item in items? {
        println!("   {:?}", item);
    }

    Ok(())
}

    TRY.
        " Scan movies for rating greater than or equal to the rating specified
        DATA(lt_attributelist) = VALUE /aws1/cl_dynattributevalue=>tt_attributevaluelist(
            ( NEW /aws1/cl_dynattributevalue( iv_n = |{ iv_rating }| ) ) ).
        DATA(lt_filter_conditions) = VALUE /aws1/cl_dyncondition=>tt_filterconditionmap(
          ( VALUE /aws1/cl_dyncondition=>ts_filterconditionmap_maprow(
          key = 'rating'
          value = NEW /aws1/cl_dyncondition(
          it_attributevaluelist = lt_attributelist
          iv_comparisonoperator = |GE|
          ) ) ) ).
        oo_scan_result = lo_dyn->scan( iv_tablename = iv_table_name
          it_scanfilter = lt_filter_conditions ).
        DATA(lt_items) = oo_scan_result->get_items( ).
        LOOP AT lt_items INTO DATA(lo_item).
          " You can loop over to get individual attributes.
          DATA(lo_title) = lo_item[ key = 'title' ]-value.
          DATA(lo_year) = lo_item[ key = 'year' ]-value.
        ENDLOOP.
        DATA(lv_count) = oo_scan_result->get_count( ).
        MESSAGE 'Found ' && lv_count && ' items' TYPE 'I'.
      CATCH /aws1/cx_dynresourcenotfoundex.
        MESSAGE 'The table or index does not exist' TYPE 'E'.
    ENDTRY.

import AWSDynamoDB


    /// Return an array of `Movie` objects released in the specified range of
    /// years.
    ///
    /// - Parameters:
    ///   - firstYear: The first year of movies to return.
    ///   - lastYear: The last year of movies to return.
    ///   - startKey: A starting point to resume processing; always use `nil`.
    ///
    /// - Returns: An array of `Movie` objects describing the matching movies.
    ///
    /// > Note: The `startKey` parameter is used by this function when
    ///   recursively calling itself, and should always be `nil` when calling
    ///   directly.
    ///
    func getMovies(firstYear: Int, lastYear: Int,
                   startKey: [Swift.String: DynamoDBClientTypes.AttributeValue]? = nil)
        async throws -> [Movie]
    {
        do {
            var movieList: [Movie] = []

            guard let client = self.ddbClient else {
                throw MoviesError.UninitializedClient
            }

            let input = ScanInput(
                consistentRead: true,
                exclusiveStartKey: startKey,
                expressionAttributeNames: [
                    "#y": "year" // `year` is a reserved word, so use `#y` instead.
                ],
                expressionAttributeValues: [
                    ":y1": .n(String(firstYear)),
                    ":y2": .n(String(lastYear))
                ],
                filterExpression: "#y BETWEEN :y1 AND :y2",
                tableName: self.tableName
            )

            let pages = client.scanPaginated(input: input)

            for try await page in pages {
                guard let items = page.items else {
                    print("Error: no items returned.")
                    continue
                }

                // Build an array of `Movie` objects for the returned items.

                for item in items {
                    let movie = try Movie(withItem: item)
                    movieList.append(movie)
                }
            }
            return movieList

        } catch {
            print("ERROR: getMovies with scan:", dump(error))
            throw error
        }
    }