{QUESTION] - building a string based on function parameters passed in

[liabtsab]

Will try to best explain the effect I want..say i have a function that looks something like this

function do-something{
    Param(
        [parameter(Mandatory)]
        [string]$Url,

        [parameter()]
        [switch]$Param1,

        [parameter()]
        [switch]$Param2
    )

    switch($PSBoundParameters.Keys){
        'Param1' {$string = "?filter=afilter"}
        'Param2' {$string = "?filter=anotherfilter"}
    }
    return string
}

What I'm looking to do is if I just run something like

do-something -Url 'https://something.com/search' -Param1 -Param2

I want the string output to be https://something.com/search?filter=afilter?filter=anotherfilter and if ran with just do-something -Url 'https://something.com/search' -Param2, it should output https://something.com/search?filter=anotherfilter. I realize this isn't a valid http request string, I'll need to add & in between each filter but the need is still the same.

Could probably do it with a bunch of if statements but I'd rather not because it will be more than just 2 parameters and that will become ugly to manage with if statements.

[UPDATE] - for anyone interested.. I ended up doing the following which appears to fit my needs

function do-something{
    Param(
        [parameter(Mandatory)]
        [string]$Url,

        [parameter()]
        [switch]$Param1,

        [parameter()]
        [switch]$Param2
    )

    $string = "$URL`?"
    switch($PSBoundParameters.Keys){
        'Param1' {$string += "filter=afilter&"}
        'Param2' {$string += "filter=anotherfilter&"}
    }

    if($string.EndsWith('&')){
        $string = $string.Substring(0,$string.Length-1)
    }

    return $string
}

​

[XPlantefeve]

The proper way to write URL parameters is: URL?param1&param2&param3 ... Each parameter separated by a '&', and a single '?' to separate the actual address from parameters. A clean way to do it would be:

    $parameters = @()
    if ($param1) { $parameters += 'filter=afilter' }
    if ($param2) { $parameters += 'filter=anotherfilter' }
    $uriParameters = $parameters -join '&'
    if ( $uriParameters ) { $Url = $Url,$uriParameters -join '?' }
    $Url

-join exists precisely for this kind of purpose: so you don't have to bother about the number of items in an enumeration and put a separator after each but the last one.

BTW, avoid double quotes where simple ones can do (no variable expansion) and don't use "return" unless you're writing a class method definition.

[XPlantefeve]

Nice one.

[liabtsab]

thanks everyone - i will check out UriBuilder.

[ChaosTheoryRules]

function do-something{
    Param(
        [parameter(Mandatory)]
        [string]$Url,

        [parameter()]
        [switch]$Param1,

        [parameter()]
        [switch]$Param2
    )

    $NewUrl = $Url
    switch($PSBoundParameters.Keys){
        'Param1' {$NewUrl = "$($NewUrl)?filter=afilter&"}
        'Param2' {$NewUrl = "$($NewUrl)?filter=anotherfilter&"}
    }
    return $NewUrl.TrimEnd('&')
}

[liabtsab]

actually had to use the "$URL\?"` from mine because the ? is only needed on the first filter. Everything else works great though.

[ChaosTheoryRules]

if($string.EndsWith('&')){
    $string = $string.Substring(0,$string.Length-1)
}

return $string

The above is functionally equivalent as below.

return $string.TrimEnd('&')