Example usage for com.amazonaws.services.dynamodbv2.document.spec ScanSpec withFilterExpression

Introduction

In this page you can find the example usage for com.amazonaws.services.dynamodbv2.document.spec ScanSpec withFilterExpression.

Prototype

public ScanSpec withFilterExpression(String filterExpression) 

Source Link

Usage

From source file:com.clicktravel.infrastructure.persistence.aws.dynamodb.DynamoDocumentStoreTemplate.java

License:Apache License

private <T extends Item> ScanSpec generateScanSpec(final AttributeQuery query, final Class<T> tableItemType)
        throws InstantiationException, IllegalAccessException, IllegalArgumentException,
        InvocationTargetException, NoSuchMethodException, SecurityException {
    final Class<?> clazz = getScanSpecOperandType(query.getAttributeName(), tableItemType);

    ScanSpec scanSpec = new ScanSpec();

    final StringBuilder filterExpression = new StringBuilder();
    final ValueMap valueMap = new ValueMap();
    int valueMapCount = 0;

    if (query.getCondition().getComparisonOperator() == Operators.NULL) {
        filterExpression.append("attribute_not_exists(").append(query.getAttributeName()).append(")");
    } else if (query.getCondition().getComparisonOperator() == Operators.NOT_NULL) {
        filterExpression.append("attribute_exists(").append(query.getAttributeName()).append(")");
    } else {/* w  w  w.ja v a2 s.  co m*/
        if (query.getCondition().getComparisonOperator() == Operators.EQUALS) {
            filterExpression.append(query.getAttributeName()).append(" IN (");

            final Iterator<String> valueIterator = query.getCondition().getValues().iterator();
            while (valueIterator.hasNext()) {
                filterExpression.append(":").append(valueMapCount);
                valueMap.with(":" + valueMapCount, valueIterator.next());
                valueMapCount++;
                if (valueIterator.hasNext()) {
                    filterExpression.append(",");
                }
            }
            filterExpression.append(")");
        } else if (query.getCondition().getComparisonOperator() == Operators.LESS_THAN_OR_EQUALS) {
            if (query.getCondition().getValues().size() == 1) {
                filterExpression.append(query.getAttributeName()).append(" <= ").append(":")
                        .append(valueMapCount);
                final Object valueInstance = clazz.getConstructor(String.class)
                        .newInstance(query.getCondition().getValues().iterator().next());
                valueMap.with(":" + valueMapCount, valueInstance);
                valueMapCount++;
            } else {
                // throw exeption??
            }
        } else if (query.getCondition().getComparisonOperator() == Operators.GREATER_THAN_OR_EQUALS) {
            if (query.getCondition().getValues().size() == 1) {
                filterExpression.append(query.getAttributeName()).append(" >= ").append(":")
                        .append(valueMapCount);
                final Object valueInstance = clazz.getConstructor(String.class)
                        .newInstance(query.getCondition().getValues().iterator().next());
                valueMap.with(":" + valueMapCount, valueInstance);
                valueMapCount++;
            } else {
                // throw exeption??
            }
        }
    }

    if (filterExpression.length() > 0) {
        scanSpec = scanSpec.withFilterExpression(filterExpression.toString());
    }
    if (valueMap.size() > 0) {
        scanSpec = scanSpec.withValueMap(valueMap);
    }
    return scanSpec;
}

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