CODEWITHSUNDEEP
aws-amplifyaws-appsync
Sanoodia
Sanoodia

Reputation: 925

AWS AppSync error after "amplify push", Value for field '$[lastSync]' must be a number

Hi im using amplify dynamodb table and at for client side using DataStore AppSync. After performing amplify push command, im getting this error in graphql SyncTable call of DataStore.

enter image description here Value for field '$[lastSync]' must be a number

Upvotes: 2

Views: 418

Answers (1)

ColaFanta
ColaFanta

Reputation: 1060

I encountered the same problem. After some investigation I found there is a bug in Amplify generated resolvers.

In line 103 of every "Query.syncXXXX.preAuth.1.req.vtl" generated by amplify (which you may find under /amplify/backend/api/[your project name]/build/resolvers)

## [Start]  Set query expression for @key **
#if( !$scan )
  #set( $limit = $util.defaultIfNull($context.args.limit, 100) )
  #set( $QueryRequest = {
  "version": "2018-05-29",
  "operation": "Sync",
  "limit": $limit,
  "lastSync": $util.toJson($util.defaultIfNull($ctx.args.lastSync, null)),
  "query": $modelQueryExpression
} )

The "lastSync" field is filled with string typed value because of the unnecessary call of "$util.toJson". This is the exact cause of your error message "$[lastSync] must be a number"

A workaround to the problem is to change:

"lastSync": $util.toJson($util.defaultIfNull($ctx.args.lastSync, null)),

into

"lastSync": $util.defaultIfNull($ctx.args.lastSync, null),

and then override the generated resolver

see Override Amplify-generated resolvers

Upvotes: 2

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