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Hello All, Is there a way to define a placeholder ...
# ask-community
m
Hello All, Is there a way to define a placeholder on a defined Parameter from the Cloud UI interface? I’d want prefect to fill the place holder at the run time basically!
k
Hey @Mehdi Nazari, you can do this my going to the Flow page then Settings then Parameters and you can set default Parameters there that will override the defaults you registered with. You can also create a Schedule under settings and attach the Parameter to the schedule.
m
Thanks @Kevin Kho, I’m talking about a place holder in a Parameter! What I have in mind is to append date to a parameter that gets passed to a flow?
k
I am a bit unclear what you mean with the placeholder in a Parameter since the Parameter is a placeholder? Will try to answer though, the parameter has to be registered on the Flow side in code. This can’t be done through the UI.
Also if you have something like
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now = Parameter("now", datetime.datetime.now())
then the datetime.datetime.now() will be evaluated during the build time and the date will be pinned during serialization. Instead you can do something like
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now = Parameter("now", default="now")
and then use a task
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@task
def get_now(time):
    if time == "now":
       return datetime.datetime.now()
m
Lets get this clear, this is what a normal Parameter on the UI looks like:
This is what I have in mind, ideally, the CURRENTDATE will get filled by Prefect at scheduled run time.
k
I think it’s not clear where this interpolation would come from. I think if you want to do this, you can use the 
context
inside your flow and pull out the relevant values.
👍 1
m
I can show you what I mean if you’re interested. The community will benefit from it if this is implemented.
k
I know what you mean. Will bring this up to the team but the short answer is there is I don’t think we would include the Parameter input or task input as a temptable field. The templating is a mechanism to template objects that need to be specified during build time, but actually get populated during runtime. For example, result location or task name. Templating these would get injected during runtime. It’s to provide the bridge of filling values of stuff that needs to be “built”. In this case though the input to the task or Parameter isn’t created at build time. It’s all deferred so I don’t think we would template that. This seems like something better handled by flow logic rather than Prefect injecting values to support the Flow.
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