Belin.Sql

1.0.0

src/Cmdlets/Get-First.psm1

using namespace System.Data
using module ../SqlCommand.psm1
using module ../SqlMapper.psm1
using module ../SqlParameterCollection.psm1

<#
.SYNOPSIS
    Executes a parameterized SQL query and returns the first row.
.OUTPUTS
    The first row.
#>
function Get-First {
    [CmdletBinding()]
    [OutputType([object])]
    param (
        # The connection to the data source.
        [Parameter(Mandatory, Position = 0)]
        [IDbConnection] $Connection,

        # The command to be executed.
        [Parameter(Mandatory, Position = 1)]
        [SqlCommand] $Command,

        # The parameters of the SQL statement.
        [Parameter(Position = 2)]
        [SqlParameterCollection] $Parameters,

        # The type of objects to return.
        [ValidateNotNull()]
        [Type] $As = [psobject]
    )

    begin {
        $dbCommand = $null
        $reader = $null
        if ($Connection.State -eq [ConnectionState]::Closed) { $Connection.Open() }
    }

    end {
        $dbCommand = $Command.ToDbCommand($Connection, $Parameters)
        $reader = $dbCommand.ExecuteReader()
        if ($reader.Read()) { [SqlMapper]::Instance.CreateInstance($As, $reader) }
        else { Write-Error "The result set is empty." -Category InvalidOperation }
    }

    clean {
        ${reader}?.Close()
        ${dbCommand}?.Dispose()
    }
}