CODEWITHSUNDEEP
node.jsamazon-web-servicesaws-lambdaamazon-dynamodb
AllenC
AllenC

Reputation: 2754

Dynamodb UpdateExpression adding new map object to a list of existing Item

I currently have a List attribute in my dynamodb table:

 name: "Test User"
 recommendations: []

I would like to add new item to the recommendations attribute using the UpdateExpression

const params = {
    TableName: 'insiders',
    Key:{
      "uuid": event.uuid, // WHERE uuid is event.uuid
    },
    UpdateExpression: "SET #recommendations = :recommendation",
    ExpressionAttributeNames: {
      "#recommendations": "recommendations",
    },
    ExpressionAttributeValues: {
      ":recommendation": [{ 
        "uuid":  `ir_${uuidv4()}`, 
        "recommendation": event.recommendation
      }]
    },
    ReturnValues:"UPDATE_NEW"
  };

  dynamodb.update(params, function(err, data) { }

I managed to add an object map to recommendations list but when I want to add another one it will replace the object in the recommendation list.

I also tried to use the ADD in UpdateExpression

const params = {
    TableName: 'insiders',
    Key:{
      "uuid": event.uuid,
    },
    UpdateExpression: "ADD #recommendations :recommendation",
    ExpressionAttributeNames: {
      "#recommendations": "recommendations",
    },
    ExpressionAttributeValues: {
      ":recommendation": [{ 
        "uuid":  `ir_${uuidv4()}`, 
        "recommendation": event.recommendation, 
      }]
    },
    ReturnValues:"ALL_NEW"
  };

   dynamodb.update(params, function(err, data) { }

but Im getting an error 

"Invalid UpdateExpression: Incorrect operand type for operator or function; operator: ADD, operand type: LIST",

Upvotes: 1

Views: 3403

Answers (1)

AllenC
AllenC

Reputation: 2754

Okay I already figured out how to add an object to existing map attribute of an item. I used list_append

this will add an object to existing map attribute

const params = {
    TableName: 'insiders',
    Key:{
      "uuid": event.uuid,
    },
    UpdateExpression: "SET #attrName = list_append(#attrName, :attrValue)",
    ExpressionAttributeNames: {
      "#attrName": "recommendations",
    },
    ExpressionAttributeValues: {
      ":attrValue": [{ 
        "uuid":  `ir_${uuidv4()}`, 
        "recommendation": event.recommendation
      }]
    },
    ReturnValues:"ALL_NEW"
  };

Upvotes: 1

Related Questions