Retool and DynamoDB

· Further Notes…

#low-code #no-sql #dynamodb #retool

If you're trying to set up a DynamoDB query in Retool and you get the error "One or more parameter values were invalid: Condition parameter type does not match schema type" then is probably because you are using the syntax:

{ ":kind": {"S": "timesheet" } }

in your expression attribute value, it seems underneath that Retool use the "DocumentClient" interface, that will infer the type of the value, so you specify your value like:

{ ":kind": "timesheet" }

After getting that going then I discovered the visual parameter editor did not have a way to specify ScanIndexForward which I needed to to set to false to get the descending order sort I needed by date. There is a workaround for this, but you have to then use the JSON editor (which confusingly is selected by a checkbox that will stay on but then be labelled "Use visual parameter editor"). In my earlier debugging I had recreated my query in the AWS cli, so I was able to sue this with the --debug flag to dig the appropriate JSON out of the log (grep for "Making request for OperationModel" in stderr). I did have to translate back the expression attribute value as above however.

I can't wait for Retool to have an easily accessible local SQL database for simple jobs like what I am working on.

So I can find it later a full query in JSON format might look like:

  "TableName": "<tablename>",
  "IndexName": "<indexname>",
  "ScanIndexForward": false,
  "KeyConditionExpression": "kind = :kind",
  "ExpressionAttributeValues": {