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LowLevelItemCRUDExample.java

/** * Copyright 2010-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved. * * This file is licensed under the Apache License, Version 2.0 (the "License"). * You may not use this file except in compliance with the License. A copy of * the License is located at * * http://aws.amazon.com/apache2.0/ * * This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR * CONDITIONS OF ANY KIND, either express or implied. See the License for the * specific language governing permissions and limitations under the License. */ package com.amazonaws.codesamples.lowlevel; import java.io.IOException; import java.util.Arrays; import java.util.HashMap; import java.util.Map; import com.amazonaws.AmazonServiceException; import com.amazonaws.auth.profile.ProfileCredentialsProvider; import com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient; import com.amazonaws.services.dynamodbv2.model.AttributeValue; import com.amazonaws.services.dynamodbv2.model.ConditionalCheckFailedException; import com.amazonaws.services.dynamodbv2.model.DeleteItemRequest; import com.amazonaws.services.dynamodbv2.model.DeleteItemResult; import com.amazonaws.services.dynamodbv2.model.GetItemRequest; import com.amazonaws.services.dynamodbv2.model.GetItemResult; import com.amazonaws.services.dynamodbv2.model.PutItemRequest; import com.amazonaws.services.dynamodbv2.model.ReturnValue; import com.amazonaws.services.dynamodbv2.model.UpdateItemRequest; import com.amazonaws.services.dynamodbv2.model.UpdateItemResult; public class LowLevelItemCRUDExample { static AmazonDynamoDBClient client = new AmazonDynamoDBClient(new ProfileCredentialsProvider()); static String tableName = "ProductCatalog"; public static void main(String[] args) throws IOException { createItems(); retrieveItem(); // Perform various updates. updateMultipleAttributes(); updateAddNewAttribute(); updateExistingAttributeConditionally(); // Delete the item. deleteItem(); } private static void createItems() { try { Map<String, AttributeValue> item1 = new HashMap<String, AttributeValue>(); item1.put("Id", new AttributeValue().withN("120")); item1.put("Title", new AttributeValue().withS("Book 120 Title")); item1.put("ISBN", new AttributeValue().withS("120-1111111111")); item1.put("Authors", new AttributeValue().withSS(Arrays.asList("Author12", "Author22"))); item1.put("Price", new AttributeValue().withN("20.00")); item1.put("Category", new AttributeValue().withS("Book")); item1.put("Dimensions", new AttributeValue().withS("8.5x11.0x.75")); item1.put("InPublication", new AttributeValue().withBOOL(false)); PutItemRequest putItemRequest1 = new PutItemRequest().withTableName(tableName).withItem(item1); client.putItem(putItemRequest1); Map<String, AttributeValue> item2 = new HashMap<String, AttributeValue>(); item2.put("Id", new AttributeValue().withN("121")); item2.put("Title", new AttributeValue().withS("Book 121 Title")); item2.put("ISBN", new AttributeValue().withS("121-1111111111")); item2.put("Price", new AttributeValue().withN("20.00")); item2.put("ProductCategory", new AttributeValue().withS("Book")); item2.put("Authors", new AttributeValue().withSS(Arrays.asList("Author21", "Author22"))); item1.put("Dimensions", new AttributeValue().withS("8.5x11.0x.75")); item1.put("InPublication", new AttributeValue().withBOOL(true)); PutItemRequest putItemRequest2 = new PutItemRequest().withTableName(tableName).withItem(item2); client.putItem(putItemRequest2); } catch (AmazonServiceException ase) { System.err.println("Create items failed."); } } private static void retrieveItem() { try { HashMap<String, AttributeValue> key = new HashMap<String, AttributeValue>(); key.put("Id", new AttributeValue().withN("120")); GetItemRequest getItemRequest = new GetItemRequest().withTableName(tableName).withKey(key) .withProjectionExpression("Id, ISBN, Title, Authors"); GetItemResult result = client.getItem(getItemRequest); // Check the response. System.out.println("Printing item after retrieving it...."); printItem(result.getItem()); } catch (AmazonServiceException ase) { System.err.println("Failed to retrieve item in " + tableName); } } private static void updateAddNewAttribute() { try { HashMap<String, AttributeValue> key = new HashMap<String, AttributeValue>(); key.put("Id", new AttributeValue().withN("121")); Map<String, AttributeValue> expressionAttributeValues = new HashMap<String, AttributeValue>(); expressionAttributeValues.put(":val1", new AttributeValue().withS("Some value")); ReturnValue returnValues = ReturnValue.ALL_NEW; UpdateItemRequest updateItemRequest = new UpdateItemRequest().withTableName(tableName).withKey(key) .withUpdateExpression("set NewAttribute = :val1") .withExpressionAttributeValues(expressionAttributeValues).withReturnValues(returnValues); UpdateItemResult result = client.updateItem(updateItemRequest); // Check the response. System.out.println("Printing item after adding new attribute..."); printItem(result.getAttributes()); } catch (AmazonServiceException ase) { System.err.println("Failed to add new attribute in " + tableName); System.err.println(ase.getMessage()); } } private static void updateMultipleAttributes() { try { HashMap<String, AttributeValue> key = new HashMap<String, AttributeValue>(); key.put("Id", new AttributeValue().withN("120")); Map<String, AttributeValue> expressionAttributeValues = new HashMap<String, AttributeValue>(); expressionAttributeValues.put(":val1", new AttributeValue().withSS("Author YY", "Author ZZ")); expressionAttributeValues.put(":val2", new AttributeValue().withS("someValue")); ReturnValue returnValues = ReturnValue.ALL_NEW; UpdateItemRequest updateItemRequest = new UpdateItemRequest().withTableName(tableName).withKey(key) .withUpdateExpression("add Authors :val1 set NewAttribute=:val2") .withExpressionAttributeValues(expressionAttributeValues).withReturnValues(returnValues); UpdateItemResult result = client.updateItem(updateItemRequest); // Check the response. System.out.println("Printing item after multiple attribute update..."); printItem(result.getAttributes()); } catch (AmazonServiceException ase) { System.err.println("Failed to update multiple attributes in " + tableName); System.out.println(ase.getMessage()); // DELETEME System.err.println("Failed to update multiple attributes in " + tableName); // DELETEME } } private static void updateExistingAttributeConditionally() { try { HashMap<String, AttributeValue> key = new HashMap<String, AttributeValue>(); key.put("Id", new AttributeValue().withN("120")); // Specify the desired price (25.00) and also the condition (price = // 20.00) Map<String, AttributeValue> expressionAttributeValues = new HashMap<String, AttributeValue>(); expressionAttributeValues.put(":val1", new AttributeValue().withN("25.00")); expressionAttributeValues.put(":val2", new AttributeValue().withN("20.00")); ReturnValue returnValues = ReturnValue.ALL_NEW; UpdateItemRequest updateItemRequest = new UpdateItemRequest().withTableName(tableName).withKey(key) .withUpdateExpression("set Price = :val1").withConditionExpression("Price = :val2") .withExpressionAttributeValues(expressionAttributeValues).withReturnValues(returnValues); UpdateItemResult result = client.updateItem(updateItemRequest); // Check the response. System.out.println("Printing item after conditional update to new attribute..."); printItem(result.getAttributes()); } catch (ConditionalCheckFailedException cse) { // Reload object and retry code. System.err.println("Conditional check failed in " + tableName); } catch (AmazonServiceException ase) { System.err.println("Error updating item in " + tableName); } } private static void deleteItem() { try { HashMap<String, AttributeValue> key = new HashMap<String, AttributeValue>(); key.put("Id", new AttributeValue().withN("120")); Map<String, AttributeValue> expressionAttributeValues = new HashMap<String, AttributeValue>(); expressionAttributeValues.put(":val", new AttributeValue().withBOOL(false)); ReturnValue returnValues = ReturnValue.ALL_OLD; DeleteItemRequest deleteItemRequest = new DeleteItemRequest().withTableName(tableName).withKey(key) .withConditionExpression("InPublication = :val") .withExpressionAttributeValues(expressionAttributeValues).withReturnValues(returnValues); DeleteItemResult result = client.deleteItem(deleteItemRequest); // Check the response. System.out.println("Printing item that was deleted..."); printItem(result.getAttributes()); } catch (AmazonServiceException ase) { System.err.println("Failed to get item after deletion " + tableName); } } private static void printItem(Map<String, AttributeValue> attributeList) { for (Map.Entry<String, AttributeValue> item : attributeList.entrySet()) { String attributeName = item.getKey(); AttributeValue value = item.getValue(); System.out.println(attributeName + " " + (value.getS() == null ? "" : "S=[" + value.getS() + "]") + (value.getN() == null ? "" : "N=[" + value.getN() + "]") + (value.getB() == null ? "" : "B=[" + value.getB() + "]") + (value.getSS() == null ? "" : "SS=[" + value.getSS() + "]") + (value.getNS() == null ? "" : "NS=[" + value.getNS() + "]") + (value.getBS() == null ? "" : "BS=[" + value.getBS() + "] \n")); } } }

Sample Details

Service: dynamodb

Last tested:

Author: AWS

Type: full-example

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