Muting create exceptions when item already exists whilst preserving other exceptions

[dmeehan1968]

I have a use case for being able to issue Model create() calls where there is a strong possibility that the record already exists (incoming data deliberately has duplicates and there is no point in overwriting the existing record (i.e. update/upsert).

I can set params.throws = false but this seems likely to mute other exceptions. As a result, I've been using try/catch and handling the case of a OneTableError with code = 'ConditionalCheckFailedException', and treating that as a duplicate that can be ignored.

My table has a primary PK that is the devId, and the SK is the deviceTime as an ISO string. The combination tells us that its a duplicate (history: index allows us to know which duplicate actually created the item so we can track losses).

Here is an example using try/catch:

         try {
              return await State.create({
                devId: device.id,
                networkTime: new Date(payload.ts),
                deviceTime: new Date(reading.timestamp * 1000),
                temperature: reading.sensor,
                history: index,
                correlationId: uplink.id,
              }, { log: false })
            } catch (e: unknown) {
              if (typeof e === 'object') {
                if (e instanceof OneTableError && e.code === 'ConditionalCheckFailedException') {
                  console.log(`duplicate for ${index}: ${new Date(reading.timestamp*1000).toISOString()}`)
                  return
                }
                throw e
              }
            }

And here is the equivilent throws: false which is cleaner, but potentially mutes other exceptions:

         return await State.create({
              devId: device.id,
              networkTime: new Date(payload.ts),
              deviceTime: new Date(reading.timestamp * 1000),
              temperature: reading.sensor,
              history: index,
              correlationId: uplink.id,
            }, { log: false, throw: false })

It seems that permit.exists is meant to address this, but I found that:

• permit.exists = false means the create only succeeds without exception if the item doesn't exist
• permit.exists = true means the create only succeeds without exception if the item does exist
• permit.exists = null means that the item is updated or inserted, rather than left alone if already existing

It seems like there is case for another param such as 'ignoreDuplicates' that handles this case more elegantly, but maybe I'm missing something.

Whilst a condition could be added to compare the fields and avoid the update, this would still raise an exception when its not exceptional (and params.throws = null might mute other exceptions).

Or in other words, there doesn't appears to be a way of saying "if this primary key already exists its not an exception, and I want to leave it alone"

[dev-embedthis]

I understand your use case. I'm not sure what the set of reasonable exceptions to to ignore would be and how to do that flexibly for all use cases.

If others have similar, but different exceptions to mute, please chime in here.