CODEWITHSUNDEEP
node.jsamazon-dynamodb
darshi sheth
darshi sheth

Reputation: 692

Update dynamodb item based on condition

I want to update an item in DynamoDB only if the new item has a more recent date than the existing item. Currently, I'm querying for the existing item, doing the comparison in my code, and then writing to db. I was wondering if there was a way to have DynamoDB do the checking and updating in single query.i have used conditionalexpression but it's not updating value even if condition satisfies. I'm working with nodejs.

Upvotes: 4

Views: 996

Answers (1)

darshi sheth
darshi sheth

Reputation: 692

I have found solution by using

Expected

clause of dynamodb. so below is my code.

var params;
  params = {
    Key: {
      "HashKey": {
        S: "Value"
      }
    },
    TableName: 'TableName',
    AttributeUpdates: {
      "Attr1": {
        Value: {
          S: "Value1"
        }
      }
    },
    Expected: {
      "Attr2": {
          "ComparisonOperator": "EQ",
          "AttributeValueList": [ {S: "Value2"} ]
      }
    }
  };
  dynamodb_client.updateItem(params, function(err, data) {
  if (err){
    console.log(err);
  } else {
    console.log(data);
  }
});

so above code updates value of Attr1 to Value 1 if Attr2 is equal to Value2

Upvotes: 2

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