/*
* Copyright 2011-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License 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.mobileconnectors.dynamodbv2.dynamodbmapper;
import com.amazonaws.services.dynamodbv2.model.AttributeValue;
import com.amazonaws.services.dynamodbv2.model.ComparisonOperator;
import com.amazonaws.services.dynamodbv2.model.Condition;
import com.amazonaws.services.dynamodbv2.model.ConditionalOperator;
import com.amazonaws.services.dynamodbv2.model.ScanRequest;
import java.util.HashMap;
import java.util.Map;
/**
* Options for filtering results from a scan operation. For example, callers can
* specify filter conditions so that only objects whose attributes match
* different conditions are returned (see {@link ComparisonOperator} for more
* information on the available comparison types).
*
* @see DynamoDBMapper#scan(Class, DynamoDBScanExpression)
*/
public class DynamoDBScanExpression {
/** Optional filter to limit the results of the scan. */
private Map<String, Condition> scanFilter;
/** The exclusive start key for this scan. */
private Map<String, AttributeValue> exclusiveStartKey;
/** The limit of items to scan during this scan. */
private Integer limit;
/**
* The total number of segments into which the scan will be divided. Only
* required for parallel scan operation.
*/
private Integer totalSegments;
/**
* The ID (zero-based) of the segment to be scanned. Only required for
* parallel scan operation.
*/
private Integer segment;
/**
* The logical operator on the filter conditions of this scan.
*/
private String conditionalOperator;
/**
* Evaluates the scan results and returns only the desired values.
* <p>
* The condition you specify is applied to the items scanned; any items that
* do not match the expression are not returned.
*/
private String filterExpression;
/**
* One or more substitution variables for simplifying complex expressions.
* The following are some use cases for an ExpressionAttributeName:
* <ul>
* <li>
* <p>
* Shorten an attribute name that is very long or unwieldy in an expression.
* </li>
* <li>
* <p>
* Create a placeholder for repeating occurrences of an attribute name in an
* expression.</li>
* <li>
* <p>
* Prevent special characters in an attribute name from being misinterpreted
* in an expression.</li>
* </ul>
* <p>
* Use the <b>#</b> character in an expression to dereference an attribute
* name. For example, consider the following expression:
* <ul>
* <li>
* <p>
* <code>order.customerInfo.LastName = "Smith" OR
* order.customerInfo.LastName = "Jones"</code></li>
* </ul>
* <p>
* Now suppose that you specified the following for
* <i>ExpressionAttributeNames</i>:
* <ul>
* <li>
* <p>
* <code>{"n":"order.customerInfo.LastName"}</code></li>
* </ul>
* <p>
* The expression can now be simplified as follows:
* <ul>
* <li>
* <p>
* <code>#n = "Smith" OR #n = "Jones"</code></li>
* </ul>
*/
private java.util.Map<String, String> expressionAttributeNames;
/**
* One or more values that can be substituted in an expression.
* <p>
* Use the <b>:</b> character in an expression to dereference an attribute
* value. For example, consider the following expression:
* <ul>
* <li>
* <p>
* <code>ProductStatus IN
* ("Available","Backordered","Discontinued")</code></li>
* </ul>
* <p>
* Now suppose that you specified the following for
* <i>ExpressionAttributeValues</i>:
* <ul>
* <li>
* <p>
* <code>{
* "a":{"S":"Available"}, "b":{"S":"Backordered"},
* "d":{"S":"Discontinued"} }</code></li>
* </ul>
* <p>
* The expression can now be simplified as follows:
* <ul>
* <li>
* <p>
* <code>ProductStatus IN
* (:a,:b,:c)</code></li>
* </ul>
*/
private java.util.Map<String, AttributeValue> expressionAttributeValues;
/**
* Returns the scan filter as a map of attribute names to conditions.
*
* @return The scan filter as a map of attribute names to conditions.
*/
public Map<String, Condition> getScanFilter() {
return scanFilter;
}
/**
* Sets the scan filter to the map of attribute names to conditions given.
*
* @param scanFilter The map of attribute names to conditions to use when
* filtering scan results.
*/
public void setScanFilter(Map<String, Condition> scanFilter) {
this.scanFilter = scanFilter;
}
/**
* Sets the scan filter to the map of attribute names to conditions given
* and returns a pointer to this object for method-chaining.
*
* @param scanFilter The map of attribute names to conditions to use when
* filtering scan results.
*/
public DynamoDBScanExpression withScanFilter(Map<String, Condition> scanFilter) {
setScanFilter(scanFilter);
return this;
}
/**
* Adds a new filter condition to the current scan filter.
*
* @param attributeName The name of the attribute on which the specified
* condition operates.
* @param condition The condition which describes how the specified
* attribute is compared and if a row of data is included in the
* results returned by the scan operation.
*/
public void addFilterCondition(String attributeName, Condition condition) {
if (scanFilter == null)
scanFilter = new HashMap<String, Condition>();
scanFilter.put(attributeName, condition);
}
/**
* Adds a new filter condition to the current scan filter and returns a
* pointer to this object for method-chaining.
*
* @param attributeName The name of the attribute on which the specified
* condition operates.
* @param condition The condition which describes how the specified
* attribute is compared and if a row of data is included in the
* results returned by the scan operation.
*/
public DynamoDBScanExpression withFilterConditionEntry(String attributeName, Condition condition) {
if (scanFilter == null)
scanFilter = new HashMap<String, Condition>();
scanFilter.put(attributeName, condition);
return this;
}
/**
* Returns the exclusive start key for this scan.
*/
public Map<String, AttributeValue> getExclusiveStartKey() {
return exclusiveStartKey;
}
/**
* Sets the exclusive start key for this scan.
*/
public void setExclusiveStartKey(Map<String, AttributeValue> exclusiveStartKey) {
this.exclusiveStartKey = exclusiveStartKey;
}
/**
* Sets the exclusive start key for this scan and returns a pointer to this
* object for method-chaining.
*/
public DynamoDBScanExpression withExclusiveStartKey(
Map<String, AttributeValue> exclusiveStartKey) {
this.exclusiveStartKey = exclusiveStartKey;
return this;
}
/**
* Returns the limit of items to scan during this scan.
* <p>
* Use with caution. Please note that this is <b>not</b> the same as the
* number of items to return from the scan operation -- the operation will
* cease and return as soon as this many items are scanned, even if no
* matching results are found. Furthermore, {@link PaginatedScanList} will
* execute as many scan operations as necessary until it either reaches the
* end of the result set as indicated by DynamoDB or enough elements are
* available to fulfill the list operation (e.g. iteration). Therefore,
* except when scanning without a scan filter, it's usually bad practice to
* set a low limit, since doing so will often generate the same amount of
* traffic to DynamoDB but with a greater number of round trips and
* therefore more overall latency.
*/
public Integer getLimit() {
return limit;
}
/**
* Sets the limit of items to scan during this scan. Please note that this
* is <b>not</b> the same as the number of items to return from the scan
* operation -- the operation will cease and return as soon as this many
* items are scanned, even if no matching results are found.
*
* @see DynamoDBScanExpression#getLimit()
*/
public void setLimit(Integer limit) {
this.limit = limit;
}
/**
* Sets the limit of items to scan and returns a pointer to this object for
* method-chaining. Please note that this is <b>not</b> the same as the
* number of items to return from the scan operation -- the operation will
* cease and return as soon as this many items are scanned, even if no
* matching results are found.
*
* @see DynamoDBScanExpression#getLimit()
*/
public DynamoDBScanExpression withLimit(Integer limit) {
this.limit = limit;
return this;
}
/**
* Returns the total number of segments into which the scan will be divided.
*/
public Integer getTotalSegments() {
return totalSegments;
}
/**
* Sets the total number of segments into which the scan will be divided.
*/
public void setTotalSegments(Integer totalSegments) {
this.totalSegments = totalSegments;
}
/**
* Sets the total number of segments into which the scan will be divided and
* returns a pointer to this object for method-chaining.
*/
public DynamoDBScanExpression withTotalSegments(Integer totalSegments) {
setTotalSegments(totalSegments);
return this;
}
/**
* Returns the ID of the segment to be scanned.
*/
public Integer getSegment() {
return segment;
}
/**
* Sets the ID of the segment to be scanned.
*/
public void setSegment(Integer segment) {
this.segment = segment;
}
/**
* Sets the ID of the segment to be scanned and returns a pointer to this
* object for method-chaining.
*/
public DynamoDBScanExpression withSegment(Integer segment) {
setSegment(segment);
return this;
}
/**
* Returns the logical operator on the filter conditions of this scan.
*/
public String getConditionalOperator() {
return conditionalOperator;
}
/**
* Sets the logical operator on the filter conditions of this scan.
*/
public void setConditionalOperator(String conditionalOperator) {
this.conditionalOperator = conditionalOperator;
}
/**
* Sets the logical operator on the filter conditions of this scan and
* returns a pointer to this object for method-chaining.
*/
public DynamoDBScanExpression withConditionalOperator(String conditionalOperator) {
setConditionalOperator(conditionalOperator);
return this;
}
/**
* Sets the logical operator on the filter conditions of this scan.
*/
public void setConditionalOperator(ConditionalOperator conditionalOperator) {
setConditionalOperator(conditionalOperator.toString());
}
/**
* Sets the logical operator on the filter conditions of this scan and
* returns a pointer to this object for method-chaining.
*/
public DynamoDBScanExpression withConditionalOperator(ConditionalOperator conditionalOperator) {
return withConditionalOperator(conditionalOperator.toString());
}
/**
* Evaluates the query results and returns only the desired values.
* <p>
* The condition you specify is applied to the items queried; any items that
* do not match the expression are not returned.
*
* @return Evaluates the query results and returns only the desired values.
* <p>
* The condition you specify is applied to the items queried; any
* items that do not match the expression are not returned.
* @see ScanRequest#getFilterExpression()
*/
public String getFilterExpression() {
return filterExpression;
}
/**
* Evaluates the query results and returns only the desired values.
* <p>
* The condition you specify is applied to the items queried; any items that
* do not match the expression are not returned.
*
* @param filterExpression Evaluates the query results and returns only the
* desired values.
* <p>
* The condition you specify is applied to the items queried; any
* items that do not match the expression are not returned.
* @see ScanRequest#setFilterExpression(String)
*/
public void setFilterExpression(String filterExpression) {
this.filterExpression = filterExpression;
}
/**
* Evaluates the query results and returns only the desired values.
* <p>
* The condition you specify is applied to the items queried; any items that
* do not match the expression are not returned.
* <p>
* Returns a reference to this object so that method calls can be chained
* together.
*
* @param filterExpression Evaluates the query results and returns only the
* desired values.
* <p>
* The condition you specify is applied to the items queried; any
* items that do not match the expression are not returned.
* @return A reference to this updated object so that method calls can be
* chained together.
* @see ScanRequest#withFilterExpression(String)
*/
public DynamoDBScanExpression withFilterExpression(String filterExpression) {
this.filterExpression = filterExpression;
return this;
}
/**
* One or more substitution variables for simplifying complex expressions.
*
* @return One or more substitution variables for simplifying complex
* expressions.
* @see scanRequest#getExpressionAttributeNames()
*/
public java.util.Map<String, String> getExpressionAttributeNames() {
return expressionAttributeNames;
}
/**
* One or more substitution variables for simplifying complex expressions.
*
* @param expressionAttributeNames One or more substitution variables for
* simplifying complex expressions.
* @see ScanRequest#setExpressionAttributeNames(Map)
*/
public void setExpressionAttributeNames(
java.util.Map<String, String> expressionAttributeNames) {
this.expressionAttributeNames = expressionAttributeNames;
}
/**
* One or more substitution variables for simplifying complex expressions.
*
* @param expressionAttributeNames One or more substitution variables for
* simplifying complex expressions.
* @return A reference to this updated object so that method calls can be
* chained together.
* @see ScanRequest#withExpressionAttributeNames(Map)
*/
public DynamoDBScanExpression withExpressionAttributeNames(
java.util.Map<String, String> expressionAttributeNames) {
setExpressionAttributeNames(expressionAttributeNames);
return this;
}
/**
* One or more substitution variables for simplifying complex expressions.
* The method adds a new key-value pair into ExpressionAttributeNames
* parameter, and returns a reference to this object so that method calls
* can be chained together.
*
* @param key The key of the entry to be added into
* ExpressionAttributeNames.
* @param value The corresponding value of the entry to be added into
* ExpressionAttributeNames.
* @see ScanRequest#addExpressionAttributeNamesEntry(String, String)
*/
public DynamoDBScanExpression addExpressionAttributeNamesEntry(String key,
String value) {
if (null == this.expressionAttributeNames) {
this.expressionAttributeNames = new java.util.HashMap<String, String>();
}
if (this.expressionAttributeNames.containsKey(key))
throw new IllegalArgumentException("Duplicated keys ("
+ key.toString() + ") are provided.");
this.expressionAttributeNames.put(key, value);
return this;
}
/**
* Removes all the entries added into ExpressionAttributeNames, setting
* ExpressAttributesNames to null
* <p>
* Returns a reference to this object so that method calls can be chained
* together.
*/
public DynamoDBScanExpression clearExpressionAttributeNamesEntries() {
this.expressionAttributeNames = null;
return this;
}
/**
* One or more values that can be substituted in an expression.
*
* @return One or more values that can be substituted in an expression.
* @see ScanRequest#getExpressionAttributeValues()
*/
public java.util.Map<String, AttributeValue> getExpressionAttributeValues() {
return expressionAttributeValues;
}
/**
* One or more values that can be substituted in an expression.
*
* @param expressionAttributeValues One or more values that can be
* substituted in an expression.
* @see ScanRequest#setExpressionAttributeValues(Map)
*/
public void setExpressionAttributeValues(
java.util.Map<String, AttributeValue> expressionAttributeValues) {
this.expressionAttributeValues = expressionAttributeValues;
}
/**
* One or more values that can be substituted in an expression.
*
* @param expressionAttributeValues One or more values that can be
* substituted in an expression.
* @return A reference to this updated object so that method calls can be
* chained together.
* @see ScanRequest#withExpressionAttributeValues(Map)
*/
public DynamoDBScanExpression withExpressionAttributeValues(
java.util.Map<String, AttributeValue> expressionAttributeValues) {
setExpressionAttributeValues(expressionAttributeValues);
return this;
}
/**
* One or more values that can be substituted in an expression. The method
* adds a new key-value pair into ExpressionAttributeValues parameter, and
* returns a reference to this object so that method calls can be chained
* together.
*
* @param key The key of the entry to be added into
* ExpressionAttributeValues.
* @param value The corresponding value of the entry to be added into
* ExpressionAttributeValues.
* @see ScanRequest#addExpressionAttributeValuesEntry(String,
* AttributeValue)
*/
public DynamoDBScanExpression addExpressionAttributeValuesEntry(String key,
AttributeValue value) {
if (null == this.expressionAttributeValues) {
this.expressionAttributeValues = new java.util.HashMap<String, AttributeValue>();
}
if (this.expressionAttributeValues.containsKey(key))
throw new IllegalArgumentException("Duplicated keys ("
+ key.toString() + ") are provided.");
this.expressionAttributeValues.put(key, value);
return this;
}
/**
* Removes all the entries added into ExpressionAttributeValues, setting
* ExpressionAttributeValues to null
* <p>
* Returns a reference to this object so that method calls can be chained
* together.
*/
public DynamoDBScanExpression clearExpressionAttributeValuesEntries() {
this.expressionAttributeValues = null;
return this;
}
}