Example usage for com.amazonaws.services.dynamodbv2.model ScanRequest setProjectionExpression

Introduction

In this page you can find the example usage for com.amazonaws.services.dynamodbv2.model ScanRequest setProjectionExpression.

Prototype

public void setProjectionExpression(String projectionExpression) 

Source Link

Document

A string that identifies one or more attributes to retrieve from the specified table or index.

Usage

From source file:org.iternine.jeppetto.dao.dynamodb.DynamoDBQueryModelDAO.java

License:Apache License

private Iterable<T> scanItems(QueryModel queryModel, ConditionExpressionBuilder conditionExpressionBuilder) {
    ScanRequest scanRequest = new ScanRequest(tableName);

    if (queryModel.getFirstResult() > 0) {
        logger.warn(//from w w  w. j a  va  2 s.  com
                "DynamoDB does not support skipping results.  Call setPosition() on DynamoDBIterable instead.");
    }

    if (queryModel.getMaxResults() > 0) {
        scanRequest.setLimit(queryModel.getMaxResults());
    }

    if (queryModel.getSorts() != null) {
        logger.warn("Not able to sort when performing a 'scan' operation.  Ignoring... ");
    }

    Map<String, String> expressionAttributeNames;

    scanRequest.setProjectionExpression(projectionExpression);

    if (conditionExpressionBuilder.hasExpression()) {
        scanRequest.setFilterExpression(conditionExpressionBuilder.getExpression());

        if (!conditionExpressionBuilder.getExpressionAttributeValues().isEmpty()) {
            scanRequest.setExpressionAttributeValues(conditionExpressionBuilder.getExpressionAttributeValues());
        }

        if (projectionExpressionNames.isEmpty()) {
            expressionAttributeNames = conditionExpressionBuilder.getExpressionAttributeNames();
        } else if (conditionExpressionBuilder.getExpressionAttributeNames().isEmpty()) {
            expressionAttributeNames = projectionExpressionNames;
        } else {
            expressionAttributeNames = new LinkedHashMap<String, String>();
            expressionAttributeNames.putAll(conditionExpressionBuilder.getExpressionAttributeNames());
            expressionAttributeNames.putAll(projectionExpressionNames);
        }
    } else {
        expressionAttributeNames = projectionExpressionNames;
    }

    if (!expressionAttributeNames.isEmpty()) {
        scanRequest.setExpressionAttributeNames(expressionAttributeNames);
    }

    return new ScanIterable<T>(dynamoDB, persistableEnhancer, scanRequest,
            rangeKeyField == null ? Collections.singleton(hashKeyField)
                    : Arrays.asList(hashKeyField, rangeKeyField));
}

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