queryCaches.ps1

using namespace System.Data
class QueryColumnCache {

#region properties. Static params for Get-SQL, query, column to use, values of that col, when to refresh
    static [hashtable]$QueryParams
    hidden    [string]$SQLQuery
    hidden    [string]$SQLColumnName
    hidden  [timeSpan]$MaxAge
            [datetime]$_LastRefresh
    hidden  [String[]]$Values
#endregion
#region constructors Sql query & first column, 60 min timeout, specify col, specify col and timeout
    QueryColumnCache ([String]$Sql) {
        #Assume first column is the one we want.
        $this.SQLQuery      = $Sql
        $this.MaxAge        = 60
        $params = [QueryColumnCache]::QueryParams
        if ($params.Count -eq 0) {throw 'No Query Parameters have been set'}
        else {
            $rows                = Get-SQL @params -SQL $this.SQLQuery
            $this.SQLColumnName  = $rows[0] | Get-Member -MemberType Property |
                                      Select-Object -First 1 -ExpandProperty name
            $this.Values         = $rows | ForEach-Object $this.SQLColumnName
            $this.LastRefresh    = Get-Date
        }
    }
    QueryColumnCache ([String]$Sql,[String]$Column) {
            $this.SQLQuery      = $Sql
            $this.SQLColumnName = $Column
            $this.MaxAge        = 60
    }
    QueryColumnCache ([String]$Sql,[String]$Column, [Int]$LifeInMinutes ) {
            $this.SQLQuery      = $Sql
            $this.SQLColumnName = $Column
            $this.MaxAge        = [timespan]::new(0,$LifeInMinutes,0)
    }
    QueryColumnCache ([String]$Sql,[String]$Column,[timespan]$MaxAge ) {
            $this.SQLQuery      = $Sql
            $this.SQLColumnName = $Column
            $this.MaxAge        = $MaxAge
    }
#endregion
#region methods. Replace toString to give sql query. Is cache fresh? Refresh it, is X known, get content
    [string]   ToString() {return $this.SQLQuery}
    [bool]     IsStale()  {return ((Get-Date) - $this.LastRefresh -gt $this.MaxAge)}
    [void]     Refresh()  {
        $params = [QueryColumnCache]::QueryParams
        if ($params.Count -eq 0) {Write-Warning 'No Query Parameters have been set'}
        else {
            $this.Values      = Get-SQL @params -SQL $this.SQLQuery  | ForEach-Object $this.SQLColumnName
            $this.LastRefresh = Get-Date
        }
    }
    [bool]     Contains(   [string]$Value){
        if   (  ($this.Values -like $value) -and -not  $this.isStale ) {
                return $true
        }
        else {
                $this.Refresh()
                return ( ($this.Values -like $value ) -as [bool])
        }
    }
    [string[]] Items(      [String]$Like) {return ($this.items() | Where-Object {$_ -like $Like}) }
    [string[]] Items()    {
        if   (  $this.IsStale() ){$this.Refresh() }
        return ($this.values)
    }
#endregion
}

class QueryRowCache   {
#region properties. Static params for Get-SQL, query, column to use, values of that col, when to refresh
    static [hashtable]$QueryParams
    hidden    [string]$SQLQuery
    hidden    [string]$SQLColumnName
            [timeSpan]$MaxAge            #Can be chnaged later
    hidden  [datetime]$_LastRefresh
    hidden [hashtable]$Values  = @{}
    hidden      [bool]$KeyOnly = $false
    hidden      [bool]$WarnedOfNoParams
#endregion
#region constructors Sql query & Column to index on, cache the whole row or just "$true" for key present  and timeout
    QueryRowCache    ([String]$Sql, [String]$KeyColumn) {
            $this.init($sql, $KeyColumn, $false,   [timespan]::new(0,60,0) )
    }
    QueryRowCache    ([String]$Sql, [String]$KeyColumn, [bool]$KeyOnly) {
            $this.init($sql, $KeyColumn, $keyonly, [timespan]::new(0,60,0) )
    }
    QueryRowCache    ([String]$Sql, [String]$KeyColumn,                 [timespan]$MaxAge ) {
            $this.init($sql, $KeyColumn, $false,   $maxAge )
    }
    QueryRowCache    ([String]$Sql, [String]$KeyColumn, [bool]$KeyOnly, [timespan]$MaxAge ) {
            $this.init($sql, $KeyColumn, $keyonly, $MaxAge )
    }

    hidden [void]init([String]$Sql, [String]$KeyColumn, [bool]$KeyOnly, [timespan]$MaxAge) {
        $this.SQLQuery      = $Sql
        $this.SQLColumnName = $KeyColumn
        $this.MaxAge        = $MaxAge
        $this.Keyonly       = $keyonly
        Add-Member -InputObject $this -MemberType ScriptProperty -Name LastRefresh -Value {$this._LastRefresh}
        Add-Member -InputObject $this -MemberType ScriptProperty -Name Count       -Value {$this.Values.Count}
    }
#endregion
#region methods. Replace toString to give sql query. Is cache fresh? Refresh it, is X known, get content
    [string]   ToString() {return $this.SQLQuery}
    [bool]     IsStale()  {return ((Get-Date) - $this.LastRefresh -gt $this.MaxAge)}
    [void]     Refresh()  {
        $params = [QueryRowCache]::QueryParams
        $rows   = 0
        $this.values.Clear()
        if     ($params.Count -eq 0 -and -not $this.WarnedOfNoParams) {
            Write-Warning 'No Query Parameters have been set'
            $this.WarnedOfNoParams = $true
        }
        elseif ($this.keyOnly) {
            $this.Values      = Get-SQL -quiet @params -SQL $this.SQLQuery  | ForEach-Object {
                $rows ++
                if ($i = $_."$($this.SQLColumnName)" -and $i -isnot [dbnull]) {$this.values[$i]= $True}
            }
            $this.LastRefresh = Get-Date
        }
        else   {
            $this.Values      = Get-SQL -quiet @params  -SQL $this.SQLQuery  | ForEach-Object {
                $rows ++
                if ($i = $_."$($this.SQLColumnName)" -and $i -isnot [dbnull]) {$this.values[$i]= $_   }
            }
            $this.LastRefresh = Get-Date
        }
        if     ($rows -gt $this.Values.count)  {
            Write-Warning "$($rows - $this.Values.count) rows were skipped"
        }
    }
    [bool]     Contains($Value){
        if   ( $this.isStale ) { $this.Refresh() }
        return $this.Values.ContainsKey($Value)
    }
    [DataRow]  Item($value) {
        if   (  $this.IsStale() ){$this.Refresh() }
        return ($this.values[$value])
    }
#endregion
}