How can one validate optional parameters? In this case EVENT BODY

[jgasyna]

Powertools validation work great for a Create (POST) with a body full of required fields. However, how would you still use the same validator for an edit / update API (PUT). Lets say we have an existing user profile and want to update the first_name field only.

You call PUT with only the "first_name" parameter and new value. I still want to validate that one field while the other fields are not there. I cannot define "required" in this case because it can be any of the original fields, and if I leave out the "required" array definition, it does not validate anything.

Using aws-lambda-powertools==1.25.10
Calling:
validate(event=event, schema=input_schema, envelope=envelopes.API_GATEWAY_HTTP)

Where the body can have artbitrary amount of the parameters on an update API.
"first_name": {
"$id": "#/properties/first_name",
"type": "string",
"max_length": 100
},

I still want to validate that it is < 100 chars
I cannot define "required": ["first_name", ... , .... ] in this event

[michaelbrewer]

You could put the validate in the method handling only the "PUT" or "GET", then you schema can be specific to that method only.

[jgasyna]

Oh yea, each API method has its own schema definition. I guess what I mean is to support something like "Partial", like in Marshmallow.
https://marshmallow.readthedocs.io/en/stable/api_reference.html
AKA ignore missing fields but validate the ones that are there. From my understanding you have to declare "required" for it to validate anything, but you would never know which fields are coming in.

[michaelbrewer]

I would have thought json schema will validate fields that where not required (optional) too. I would have to test this myself.

[jgasyna]

Yea so an easy test for this is to have "required" : [], the validate function will not validate anything (At least in my experience). I believe its the same as omitting the required keyword altogether in the schema definition. Thanks for your help. I kind of assumed you could declare the fields as "optional" or something similar, but still have validation for that field (such as max_length)

[heitorlessa]

Hey @jgasyna your use case will be best handled by Parser (Pydantic): https://awslabs.github.io/aws-lambda-powertools-python/latest/utilities/parser/

While you could use optional fields in JSON Schemas, I can see you have experience with marshmallow so Parser/Pydantic will feel like second nature to you.

[michaelbrewer]

But on the above limitation (which is super strange), then Parser is a better (if heavier) option.

[jgasyna]

So after some poking around, it appears that it is actually best "REST" practice to send the whole payload in a PUT operation. This will solve the issue above. (So basically the diff between a PUT and PATCH). It is still strange, however, that optional / partial field are not supported in API GATEWAY power-tools validation. I guess I would suggest a feature request to support PATCH API calls in the future.

[heitorlessa]

Sorry typing on my phone and forgot to send the link to Draft 7 of JSON Schema on conditional validation. http://json-schema.org/draft-07/json-schema-release-notes.html There’s an “if” “else” in JSON Schema that you could define a required field optional IF X == Y (“PATCH”). In my humble opinion, this is problematic in JSON Schema because it turns a stateless validation into an inflexible format to handle varying states - it could go wrong easily if your number of dependent fields grow, hence the suggestion to consider Parser. Example { "type": "object", "properties": { "foo": { "type": "string" }, "bar": { "type": "string" } }, "if": { "properties": { "foo": { "const": "bar" } }, "required": ["foo"] }, "then": { "required": ["bar"] } }

…

On Mon, 13 Jun 2022 at 20:40, Heitor Lessa ***@***.***> wrote: Perhaps I misunderstood your question completely. When you have the bandwidth, could you open up a feature request on this? Powertools Validator uses fastjsonschema library to validate dicts using a JSON Schema. If this is supported in JSON Schema (optional fields are a feature), then we should look into this. For strict typing at runtime, deep and conditional validations, and data remapping/scrubbing Parser utility is best. If you don’t have the bandwidth and could share a sample anonymised payload and the expected outcome you’d like, we’re happy to create it on your behalf. Thank you On Mon, 13 Jun 2022 at 20:11, jgasyna ***@***.***> wrote: > So after some poking around, it appears that it is actually best "REST" > practice to send the whole payload in a PUT operation. This will solve the > issue above. (So basically the diff between a PUT and PATCH). It is still > strange, however, that optional / partial field are not supported in API > GATEWAY power-tools validation. I guess I would suggest a feature request > to support PATCH API calls in the future. > > — > Reply to this email directly, view it on GitHub > <#1246 (comment)>, > or unsubscribe > <https://github.com/notifications/unsubscribe-auth/AAZPQBFPQD223QS7DFMHM5DVO52VBANCNFSM5YOZRFYQ> > . > You are receiving this because you commented.Message ID: > <awslabs/aws-lambda-powertools-python/repo-discussions/1246/comments/2940927 > @github.com> >

[heitorlessa]

Perhaps I misunderstood your question completely. When you have the bandwidth, could you open up a feature request on this? Powertools Validator uses fastjsonschema library to validate dicts using a JSON Schema. If this is supported in JSON Schema (optional fields are a feature), then we should look into this. For strict typing at runtime, deep and conditional validations, and data remapping/scrubbing Parser utility is best. If you don’t have the bandwidth and could share a sample anonymised payload and the expected outcome you’d like, we’re happy to create it on your behalf. Thank you

…

On Mon, 13 Jun 2022 at 20:11, jgasyna ***@***.***> wrote: So after some poking around, it appears that it is actually best "REST" practice to send the whole payload in a PUT operation. This will solve the issue above. (So basically the diff between a PUT and PATCH). It is still strange, however, that optional / partial field are not supported in API GATEWAY power-tools validation. I guess I would suggest a feature request to support PATCH API calls in the future. — Reply to this email directly, view it on GitHub <#1246 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAZPQBFPQD223QS7DFMHM5DVO52VBANCNFSM5YOZRFYQ> . You are receiving this because you commented.Message ID: <awslabs/aws-lambda-powertools-python/repo-discussions/1246/comments/2940927 @github.com>