Hi
I think if we want to go with ‘?’ as a marker for the optional parameter then
that question mark could be better put at the end of parameter name:
from("jms:cheese?concurrentConsumers={{speedUp?}}")
Like it’s the case in TS:
https://www.typescriptlang.org/docs/handbook/functions.html#optional-and-default-parameters
<https://www.typescriptlang.org/docs/handbook/functions.html#optional-and-default-parameters>
It’s also the same syntax for optional chaining in JS itself:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Optional_chaining
<https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Optional_chaining>
Babak
> On 5 Mar 2021, at 15:04, Claus Ibsen <[email protected]> wrote:
>
> Hi
>
> In Camel 3.9 we are introducing optional property placeholders.
> https://issues.apache.org/jira/browse/CAMEL-16302
>
> The use-case is to allow configuring Camel endpoints (primarily) where
> you can specify some options that may be configured or not (optional).
>
> Currently all property placeholders are mandatory, unless a default
> value is provided. So with the default value, you could do "optional"
> but then you would need to know what the default value would be (if
> there is any).
>
> Optional placeholders is also a feature that we want to have with
> route templates (aka Kamelets). So you can create kamelets with a
> number of options (some are required, and others would be optional).
> And others have default values etc.
>
> The syntax for marking a property placeholder as option is to prefix
> the key name with ?, eg
>
> from("jms:cheese?concurrentConsumers={{?speedUp}}")
>
> Here the concurrent consumers option is optional, as the placeholder
> value starts with a ? in the key name.
>
> Then the Camel end user can configure the property placeholder, such
> as in application.properties
>
> speedUp=5
>
> Or if there are no configuration, then the option is not present and
> the endpoint is resolved as:
>
> from("jms:cheese")
>
>
> The syntax with the ? mark was choose to keep it short. But we are
> open for feedback.
> Another alternative was to prefix with optional:
>
> {{optional:speedUp}}
>
> However the properties component in Camel then assume the key is named
> optional, and the default value is speedUp. So it clashes with this.
> But we could make "optional" a reserved word and do special handling
> for this.
>
> The only concern about using ? is that an endpoint uri already have ?
> for query parameters. And if using more ? would be confusing?
>
>
> from("jms:cheese?concurrentConsumers={{?speedUp}}&subscrtiptionName={{someName}}")
>
> Any thoughts?
>
>
> --
> Claus Ibsen
> -----------------
> http://davsclaus.com @davsclaus
> Camel in Action 2: https://www.manning.com/ibsen2
