CODEWITHSUNDEEP
javaamazon-web-servicesamazon-dynamodbnosql
Bryan Benauro
Bryan Benauro

Reputation: 147

DynamoDB DynamoDBQueryExpression mixed Conditional Operator

What is the best way to do complex queries using DynamoDBQueryExpression.

By default the fetch will executed an AND on all the Conditions provided.

How do i execute something like (C1 && C2 && (C3|| C4|| C5))? Is it even possible with DynamoDB java api?

Upvotes: 1

Views: 2932

Answers (1)

notionquest
notionquest

Reputation: 39226

DynamoDB supports the complex conditions using "com.amazonaws.services.dynamodbv2.document.spec.QuerySpec". You can write the AND and OR conditions using FilterExpression.

Please see the example below:-

1) withKeyConditionExpression - For hash key and range key expressions

2) withFilterExpression - For all other attributes (i.e. other than key attributes)

ItemCollection<QueryOutcome> items = null;

        QuerySpec querySpec = new QuerySpec();

        ValueMap valueMap = new ValueMap();
        valueMap.withString(":autoIdVal", autoID);
        valueMap.withString(":docTypeVal", docType);
        valueMap.withString(":username", username);
        valueMap.withString(":comment", comment);

        Map<String, String> nameMap = new LinkedHashMap<>();
        nameMap.put("#comment", "comment");

        querySpec.withKeyConditionExpression("autoID = :autoIdVal").withFilterExpression("(docType = :docTypeVal AND username = :username) OR (#comment = :comment)")
                .withValueMap(valueMap)
                .withNameMap(nameMap);

        items = table.query(querySpec);

        Iterator<Item> iterator = items.iterator();

        Item itemData = null;

        while (iterator.hasNext()) {
            itemData = iterator.next();

            System.out.println("Json data ====================>" + itemData.toJSONPretty());

        }

Upvotes: 3

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