How to query a StringSet value in DynamoDB (iOS)?

Question

I am trying to find out how to search some rows with a specific tag contained in a StringSet in AWS DynamoDB with the AWS SDK v2 for iOS.

I couldn't find anything for doing this in the official Amazon iOS documentation for DynamoDB, so I tried this expression but it doesn't work:

let queryExpression = AWSDynamoDBQueryExpression()
queryExpression.limit = 300
queryExpression.filterExpression = "tags CONTAINS :tag"
queryExpression.expressionAttributeValues = [":tag": self.searchQueryTag]

Global.appDelegate().dynamoDBObjectMapper.query(BlogPost.self, expression: queryExpression)
    .continueWithBlock({(task: AWSTask) -> AnyObject? in

    if (task.exception != nil || task.error != nil)
    {
        completion(response: 0)
    }
    else if ((task.result) != nil)
    {
        if(task.result!.count > 0)
        {
            // LIST ALL IDS…
        }
        else
        {
            completion(response: 0)
        }
    }

    return nil
})

Can somebody teach me how to query as specific string in StringSets (NSSets) in DynamoDB by using the AWS iOS SDK?

Varoon · Accepted Answer · 2016-11-30 19:34:57Z

5

Change this line

queryExpression.filterExpression = "tags CONTAINS :tag"

to this

queryExpression.filterExpression = "contains(tags,:tag)"

answered Nov 30, 2016 at 19:34

Varoon

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1 Comment

Joseph Astrahan Over a year ago

Wow this was hard to find this answer, great job!

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