How to get all partition key vlaues?

Question

Hello guys, I want to know how we can fetch all values from partition keys columns by using node js. I write one code but don't know how to pass value in ExpressionAttributeValues with :id

```
function getPartition(){
    var params = {
        ExpressionAttributeValues:{
            ':id': ''
        },
        FilterExpression: 'Id=:id',
        ProjectionExpression:'id',
        TableName: 'testing'
    };
    docClient.scan(params, function(err,data){
        if(err) console.log(err,err.stack);
        else console.log(data);
    })
}

```
with this, it returns me only the scanned count but not the items of the ID column. Where I am doing wrong, I just need to all values from the ID column which is the partition key. Thanks

Accepted Answer

Based on your recent comment, this code will return you only the list of PK's for your table:

Using Scan you will read each item in the table. `ProjectionExpression` tells DynamoDB only to return attributes which match that value, in your case `id`.

```
var params = {
  TableName : 'TableName',
  ProjectionExpression: 'id'
};

documentClient.scan(params, function(err, data) {
  if (err) console.log(err);
  else console.log(data);
});
```

Answer

Its not clear what you are looking for here.

I'm going to base this on the assumption that you want to get all the attributes which is stored for a given `id` with `id` being your partition key?

You should use [Query](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_Query.html) which will target a single Item Collection and be much more efficient than a [Scan](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_Scan.html) which reads all the items in the table.

```
    var params = {
        TableName: 'TableName',
        KeyConditionExpression: 'Id = :id',
        ExpressionAttributeValues: {
          ':id': '123456'
        }
      };

documentClient.query(params, function(err, data) {
        if (err) console.log(err);
        else console.log(data);
     });
```

Furthermore, if you do not have a SortKey on your table, you can also use [GetItem](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_GetItem.html) as each item will have a unique `ID`:

```
     var params = {
        TableName : 'TableName',
        Key: {
          id: '123456'
        }
      };

documentClient.get(params, function(err, data) {
        if (err) console.log(err);
        else console.log(data);
      });
```

How to get all partition key vlaues?

Relevanter Inhalt