LAE

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Originally posted by: johnpelz

Is there a way turn off the parameter "pre-validation" in a node using a BRAINScript expression?

For example, we have a paramter that we want to be optional in a sort node for kind of dynamic sort approach (additional sort keys); however, the following will cause a validation error if the parameter is left blank:

if ("{{^SORT_KEYS^}}".trim().len() > 0) and "{{^SORT_KEYS^}}".isNotNull() then
AMOUNT
else
list(AMOUNT, {{^SORT_KEYS^}})

Any ideas? Node is posted below:

node:Sort
bretype:core::Sort
editor:sortkey=4834520d63f712a4
input:@40fd2c743ebf4304/=Head.42fbf39e14aa2417
output:@40fd2c746a2a3b47/=
prop:CompareOrderExpr=<<EOX
if ("{{^SORT_KEY^}}".trim().len() > 0) and "{{^SORT_KEY^}}".isNotNull() then
AMOUNT
else
AddrString
EOX
prop:SORT_KEY=A
editor:XY=760,140
editor:propdef=SORT_KEY|string|1||None
end:Sort

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Originally posted by: mmarinelli

Yes, you can set defaults for parameters which will be evaluated when the parameters are not populated. In your case, use {{^SORT_KEYS=^}} to have the parameter default to an empty string.

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Originally posted by: tczotter

Mark is right. You should always be thinking about what to use if a value is not filled in, when you invoke textual substitution.

This allows each request to supply an appropriate default value - they may not all be the same.

Another approach is to actually put a value into the base node, so all instances inherit a default.

In this case, however, you intend for the default to be the empty string. There is a special representation for this. Set the initial default value of the parameter (not the request for the parameter, the parameter itself) to the value

{{^^}}

That sequence is the BRE equivalent to the statement "this space intentionally left blank" which satisfies the requirement that it is, in fact, not blank.

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Originally posted by: dstacey

Hi,

I tried the above to allow for an optional parameter (e.g. Field = {{^SORT_KEYS=^}}) and it works great when I directly leave the node parameter blank - but I want the node parameter to be able to optionally inherit from a global parameter (say GLOBAL_KEY) which in turn I want to be able to leave optionally blank. Now when I leave GLOBAL_KEY blank I still get the "Parameter GLOBAL_KEY not defined" error when I execute the Field = {{^SORT_KEYS=^}} instruction.

How might I solve this?

Many thanks,
Dave

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Originally posted by: Tim Meagher

Can you post an example graph showing the problem you are having?
Attached is an example of what I *think* you are trying to do, but I'm not sure.
Attachments:
GlobalKeys.brg

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Originally posted by: dstacey

Tim,

Your graph captures exactly what I am trying to do - when I tried it I only had the reference {{^GLOBAL_KEY}} in my composite rather than {{^GLOBAL_KEY=^}}.

Thanks,
Dave