Adding timestamp automatically through AWS Appsync resolver with Dynamodb

Question

I tried to add timestamp automatically when I create some post. But it is not working the example of appsync resolver-context-reference.

https://docs.aws.amazon.com/appsync/latest/devguide/resolver-context-reference.html#time-helpers-in-util-time

{
    "version" : "2017-02-28",
    "operation" : "PutItem",
    "key": {
        "id" : $util.dynamodb.toDynamoDBJson($util.autoId())
    },

    #set( $myfoo = $util.dynamodb.toMapValues($ctx.args) )
    #set( $myFoo.version = $util.dynamodb.toNumber(1) )
    #set( $myFoo.timestamp = $util.time.nowISO8601() )

    "attributeValues" : $util.toJson($myFoo)
}

Are you trying to set the timestamp while writing to the DB or upon returning the values? Looks likes the latter. — Vladimir
– Vladimir, Commented May 7, 2018 at 2:00

Vladimir · Accepted Answer · 2018-05-08 01:51:57Z

7

This is a working example of what you're looking to do (taken from my AppSync API resolver). Note the "messageId" and "createdDate" attributes. That's how you can add a date while writing to DDB.

{
  "version": "2017-02-28",
  "operation": "PutItem",
  "key": {
    "eventId": $util.dynamodb.toDynamoDBJson($ctx.args.input.eventId),
    "messageId": $util.dynamodb.toDynamoDBJson("$util.time.nowISO8601()$util.autoId()"),
  },
  "attributeValues": {
    "message": $util.dynamodb.toDynamoDBJson($ctx.args.input.message),
    "createdDate": $util.dynamodb.toDynamoDBJson($util.time.nowISO8601())
  }
}

answered May 8, 2018 at 1:51

Vladimir

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3 Comments

Jeff Gu Kang Over a year ago

Is it work correctly as "$util.time.nowISO8601()$util.autoId()"?

Vladimir Over a year ago

Yes. You can use additional values for sorting and range purposes as well. Up to you. Here's a good guide to follow: docs.aws.amazon.com/amazondynamodb/latest/developerguide/…

Suvoraj Biswas Over a year ago

I was strugging on how to pass the current itmestamp to dynamodb to fetch a result and found this post and used this --> $util.dynamodb.toDynamoDBJson($util.time.nowISO8601()) and it worked like charm. Thanks for the code snippet. You saved my day.

pauldendulk · Accepted Answer · 2019-10-12 11:50:05Z

5

Change your resolver to the following

{
    "version" : "2017-02-28",
    "operation" : "PutItem",
    "key": {
        "id" : $util.dynamodb.toDynamoDBJson($util.autoId())
    },

    #set( $myFoo = $util.dynamodb.toMapValues($ctx.args) )
    #set( $myFoo.version = $util.dynamodb.toNumber(1) )
    #set( $myFoo.timestamp = $util.dynamodb.toDynamoDB($util.time.nowISO8601()) )

    "attributeValues" : $util.toJson($myFoo)
}

Also note the call to $util.time.nowISO8601() is now wrapped with $util.dynamodb.toDynamoDB()

edited Oct 12, 2019 at 11:50

pauldendulk

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answered May 9, 2018 at 2:15

hatboyzero

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Comments

Jeff Gu Kang · Accepted Answer · 2018-05-14 03:20:12Z

1

For dynamoDB, String should change to dynamodb type through $util. Thus, it would be work after changing time string to dynamoDB type.

#set( $myFoo.timestamp = $util.time.nowISO8601() )
=>  
#set( $myFoo.timestamp = $util.dynamodb.toDynamoDB($util.time.nowISO8601())

edited May 14, 2018 at 3:20

answered May 4, 2018 at 4:28

Jeff Gu Kang

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