DynamoDB : Getting attributes of every item of array

Question

I'm trying to BatchGetItem with an array of primary keys, but the problem is BatchGetItem want

Keys : [ 
 { 'username' : 'username1'} 
 { 'username' : 'username2'}
]

instead of

Keys : [ 'username' : ':someUsernameArray' ]

---

Here is the part of my Lambda Function (in Node.js)

var follower_arr = Array.from(data.Item.followers.values);

var follower_params = {
    RequestItems : {
        USER : { 
            Keys :?,
            ProjectionExpression : "university.#name,full_name,username",
            "ConsistentRead": false,
            "ExpressionAttributeNames": { 
                "#name" : "name" 
             }    
        },
    }
}

docClient.batchGet(follower_params,function(err,data){
    if(err){
        callback(err,null);
    }else{
        callback(null,data);
    }
});

follower_arr value is an array of usernames such as,

['jack', 'michael_is_cool', 'mark_me_but', 'brownie_mr_brown']

So how can I get the attributes of all the elements of array which consists of primary keys?

Answer 1

You need to convert the array of usernames into an array of objects as show below. Use the resultant array in your query parameters.

follower_arr.forEach(function (ele) {
    keys.push({ username: ele })
}) 

var follower_params = {
    RequestItems : {
        USER : { 
            Keys :keys   
        },
    }
}