java - 在java中从DynamoDB本地检索选定的数据

Question

我已在本地 dynamoDB 中创建了一个表。这些字段是，

id (N)
name (S)
school (S)
classname (S)

现在我想检索学校等于“xschool”的所有记录并打印。

尝试了下面的代码，但它在查询中给了我一个错误，

QuerySpec spec = new QuerySpec().withProjectionExpression("sid, classname, school")
            .withKeyConditionExpression("school = :v_school").
            withValueMap(new ValueMap().withString(":v_school", "abcschool"));

        ItemCollection<QueryOutcome> items = table.query(spec);

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

        while (iterator.hasNext()) {
            System.out.println(iterator.next().toJSONPretty());
        }

因为我是 dynamoDB 的新手，所以对此有何建议。

Answer 1

AmazonDynamoDB dynamoDBClient = createClient();
DynamoDB dynamoDB = new DynamoDB(dynamoDBClient);        

String tableName = "student";
Table table = dynamoDB.getTable(tableName);

Map<String, Object> expressionAttributeValues = new HashMap<String, Object>();
expressionAttributeValues.put(":sc", schoolname);

ItemCollection<ScanOutcome> items = table.scan("school = :sc", // FilterExpression
    "sid, school, firstname, classname", // ProjectionExpression
    null, // ExpressionAttributeNames - not used in this example
    expressionAttributeValues);

Iterator<Item> iterator = items.iterator();
while (iterator.hasNext()) {
    System.out.println(iterator.next().toJSONPretty());
}

试试这个，我想这对你有用