functions/Out-DbaDataTable.ps1

Function Out-DbaDataTable
{
<#
.SYNOPSIS
Creates a DataTable for an object
     
.DESCRIPTION
Creates a DataTable based on an objects properties. This allows you to easily write to SQL Server tables.
     
Thanks to Chad Miller, this is based on his script. https://gallery.technet.microsoft.com/scriptcenter/4208a159-a52e-4b99-83d4-8048468d29dd
 
.PARAMETER InputObject
The object to transform into a DataTable
     
.PARAMETER TimeSpanType
Sets what type to convert TimeSpan into before creating the datatable. Options are Ticks, TotalDays, TotalHours, TotalMinutes, TotalSeconds, TotalMilliseconds and String.
 
.PARAMETER IgnoreNull
If this switch is used, objects with null values will be ignored (empty rows will be added by default)
 
.PARAMETER Silent
Use this switch to disable any kind of verbose messages
 
.NOTES
dbatools PowerShell module (https://dbatools.io)
Copyright (C) 2016 Chrissy LeMaire
This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.
 
.LINK
 https://dbatools.io/Out-DbaDataTable
 
.EXAMPLE
Get-Service | Out-DbaDataTable
 
Creates a $datatable based off of the output of Get-Service
     
.EXAMPLE
Out-DbaDataTable -InputObject $csv.cheesetypes
 
Creates a DataTable from the CSV object, $csv.cheesetypes
     
.EXAMPLE
$dblist | Out-DbaDataTable
 
Similar to above but $dbalist gets piped in
 
.EXAMPLE
Get-Process | Out-DbaDataTable -TimeSpanType TotalSeconds
 
Creates a DataTable with the running processes and converts any TimeSpan property to TotalSeconds.
 
#>
    
    [CmdletBinding()]
    [OutputType([System.Object[]])]
    param (
        # Input object to process
        [Parameter(Position = 0,
                   Mandatory = $true,
                   ValueFromPipeline = $true)]
        [AllowNull()]
        [PSObject[]]$InputObject,
        
        # What to convert TimeSpan to
        [Parameter(Position = 1)]
        [ValidateSet("Ticks",
                     "TotalDays",
                     "TotalHours",
                     "TotalMinutes",
                     "TotalSeconds",
                     "TotalMilliseconds",
                     "String")]
        [ValidateNotNullOrEmpty()]
        [string]$TimeSpanType = "TotalMilliseconds",        
        
        # If this switch is used, objects with null values will be ignored (empty rows will be added by default)
        [switch]$IgnoreNull,
        
        # Use this switch to disable any kind of verbose messages
        [switch]$Silent   
    )
    
    Begin
    {
        
        function ConvertType 
        {
            # This function will check so that the type is an accepted type which could be used when inserting into a table.
            # If a type is accepted (included in the $type array) then it will be passed on, otherwise it will first change type before passing it on.
            # Special types will have both their types converted as well as the value.
            # TimeSpan is a special type and will be converted into the $timespantype. (default: TotalMilliseconds)
            # so that the timespan can be store in a database further down the line.
            param (
                $type,
                $value,
                $timespantype = 'TotalMilliseconds'
            )

            $types = [System.Collections.ArrayList]@(
                'System.Int32',
                'System.UInt32',
                'System.Int16',
                'System.UInt16',
                'System.Int64',
                'System.UInt64',
                'System.Decimal',
                'System.Single',
                'System.Double',
                'System.Byte',
                'System.SByte',
                'System.Boolean',
                'System.DateTime',
                'System.Guid',
                'System.Char'
            )

            # The $special variable is used to mark the return value if a conversion was made on the value itself.
            # If this is set to true the original value will later be ignored when updating the DataTable.
            # And the value returned from this function will be used instead. (cannot modify existing properties)
            $special = $false

            # Special types need to be converted in some way.
            # This attempt is to convert timespan into something that works in a table.
            # I couldn't decide on what to convert it to so the user can decide.
            # If the parameter is not used, TotalMilliseconds will be used as default.
            # Ticks are more accurate but I think milliseconds are more useful most of the time.
            if ($type -eq 'System.TimeSpan') {
                $special = $true
                if ($timespantype -eq 'String') {
                    $value = $value.ToString()
                    $type = 'System.String'
                }
                else {
                    # Lets use Int64 for all other types than string.
                    # We could match the type more closely with the timespantype but that can be added in the future if needed.
                    $value = $value.$timespantype
                    $type = 'System.Int64'
                }
            }
            elseif (!$types.Contains($type)) {
                # All types which are not found in the array will be converted into strings.
                # In this way we dont ignore it completely and it will be clear in the end why it looks as it does.
                $type = 'System.String'
            }
            
            # return a hashtable instead of an object. I like hashtables :)
            return @{ type=$type; Value=$value; Special=$special}
        }
    
        $datatable = New-Object System.Data.DataTable
        $specialColumns = @{} # will store names of properties with special data types
        
        # The shouldCreateColumns variable will be set to false as soon as the column definition has been added to the data table.
        # This is to avoid that the rare scenario when columns are not created because the first object is null, which can be accepted.
        # This means that we cannot relly on the first object to create columns, hence this variable.
        $ShouldCreateCollumns = $true
    }
    
    Process
    {
        if (!$InputObject) {
            if ($IgnoreNull) {
                # If the object coming down the pipeline is null and the IgnoreNull parameter is set, ignore it.
                Write-Message -Message "The InputObject from the pipe is null. Skipping." -Silent:$Silent -Warning
            }
            else {
                # If the object coming down the pipeline is null, add an empty row and then skip to next.
                $datarow = $datatable.NewRow()
                $datatable.Rows.Add($datarow)
            }
        } else {
            foreach ($object in $InputObject) {
                if (!$object) {
                    if ($IgnoreNull) {
                        # If the object in the array is null and the IgnoreNull parameter is set, ignore it.
                        Write-Message -Message "Object in array is null. Skipping." -Silent:$Silent -Warning
                    }
                    else {
                        # If the object in the array is null, add an empty row and then skip to next.
                        $datarow = $datatable.NewRow()
                        $datatable.Rows.Add($datarow)
                    }
                } else {
                    $datarow = $datatable.NewRow()
                    foreach ($property in $object.PsObject.get_properties()) {
                        # The converted variable will get the result from the ConvertType function and used for type and value conversion when adding to the datatable.
                        $converted = @{}
                        if ($ShouldCreateCollumns) {
                            # this is where the table columns are generated
                            if ($property.value -isnot [System.DBNull]) {
                                # Check if property is a ScriptProperty, then resolve it while calling ConvertType. (otherwise we dont get the proper type)
                                Write-Verbose "Attempting to get type from property $($property.Name)"
                                If ($property.MemberType -eq 'ScriptProperty') {
                                    try {
                                        $converted = ConvertType -type ($object.($property.Name).GetType().ToString()) -value $property.value -timespantype $TimeSpanType
                                    } catch {
                                        # Ends up here when the type is not possible to get so the call to ConvertType fails.
                                        # In that case we make a string out of it. (in this scenario its often that a script property points to a null value so we can't get the type)
                                        $converted = @{
                                            type='System.String'
                                            Value=$property.value
                                            Special=$false
                                        }
                                    }
                                    # We need to check if the type returned by ConvertType is a special type.
                                    # In that case we add it to the $specialColumns variable for future reference.
                                    if ($converted.special) {
                                        $specialColumns.Add($property.Name, $object.($property.Name).GetType().ToString())
                                    }
                                } else {
                                    $converted = ConvertType -type $property.TypeNameOfValue -value $property.value -timespantype $TimeSpanType
                                    # We need to check if the type returned by ConvertType is a special type.
                                    # In that case we add it to the $specialColumns variable for future reference.
                                    if ($converted.special) {
                                        $specialColumns.Add($property.Name, $property.TypeNameOfValue)
                                    }
                                }
                            }
                            $column = New-Object System.Data.DataColumn
                            $column.ColumnName = $property.Name.ToString()
                            $column.DataType = [System.Type]::GetType($converted.type)
                            $datatable.Columns.Add($column)
                        } 
                        else {
                            # This is where we end up if the columns has been created in the data table.
                            # We still need to check for special columns again, to make sure that the value is converted properly.
                            if ($property.value -isnot [System.DBNull]) {
                                if ($specialColumns.Keys -contains $property.Name) {
                                    $converted = ConvertType -type $specialColumns.($property.Name) -value $property.Value -timespantype $TimeSpanType
                                }
                            }
                        }

                        if ($property.value.length -gt 0) {
                            if ($property.value.ToString() -eq 'System.Object[]') {
                                $datarow.Item($property.Name) = $property.value -join ", "
                            }
                            else {
                                # If the typename was a special typename we want to use the value returned from ConvertType instead.
                                # We might get error if we try to change the value for $property.value if it is read-only. That's why we use $converted.value instead.
                                if ($converted.special) {
                                    $datarow.Item($property.Name) = $converted.value
                                }
                                else {
                                    $datarow.Item($property.Name) = $property.value
                                }
                            }        
                        }
                    }

                    $datatable.Rows.Add($datarow)
                    # If this is the first non-null object then the columns has just been created.
                    # Set variable to false to skip creating columns from now on.
                    if ($ShouldCreateCollumns) {
                        $ShouldCreateCollumns = $false
                    }
                }
            }
        }
    }
    
    End
    {
        return @( ,($datatable))
    }
}