# Get-BomRows

This function is called recursively for loading the BOM tree.\
The returned [BomRow](</code_reference/commandlets/show-bomwindow/objects/bomrow>) are the children of the [BOMs](</code_reference/commandlets/show-bomwindow/objects/bom>) shown in the BOM Window.

## Syntax

```powershell
Get-BomRows [-BomHeader] <Item>
```

## Parameters

| Type                                                                 | Name      | Description                                            | input/output | Mandatory | Default value |
|----------------------------------------------------------------------|-----------|--------------------------------------------------------|--------------|-----------|---------------|
| [BomRow](</code_reference/commandlets/show-bomwindow/objects/bomrow>)  | BomHeader | The parent element for which bom rows must be returned | input        | yes       |               |


## Return type

PSObject\[\] ← typically an array of powerVault [FileBomRows](<inv:powervault#code_reference/objects/filebomrow>) or [ItemBomRows](<inv:powervault#code_reference/objects/itembomrow>) or *empty*.\
It is recommended for every BomRow to provide at least the following [properties](</code_reference/commandlets/show-bomwindow/objects/bomrow>) :
> - `_Name` ← serves as the unique identifier for every [BOM](</code_reference/commandlets/show-bomwindow/objects/bom>) and [Item](</code_reference/commandlets/show-bomwindow/objects/item>) 
> - `Bom_Number`
> - `Bom_PositionNumber`
> - `Bom_Quantity`

## Remarks

The first time the function is called for the root entity, which is passed to the [Show-BomWindow](</code_reference/commandlets/show-bomwindow>) *-Entity* parameter.\
For each returned [BomRow](</code_reference/commandlets/show-bomwindow/objects/bomrow>), the function is then invoked again recursively until no more new rows are returned and the complete BOM structure is loaded.\
In order to signal a leaf of the BOM tree (a BomRow that has no more children) the function should return an *empty array*.

**Note:** The function will only be called once for BOMs that are located multiple times in the BOM tree.

In general two categories of [properties](</code_reference/commandlets/show-bomwindow/objects/bomrow>) can be provided for all the BomRows:
> - BOM properties are properties prefixed with 'Bom\_' (e.g. `Bom_PositionNumber`, `Bom_Unit`, ...). </br> They are displayed only in the BOM-Tab without the prefix.
> - Entity properties are all other properties (e.g. `Description`, `_Category`, ...). </br> They are available in both the BOM-Tab and the Items-Tab.

Since every BomRow is a *PSObject*, custom [BOM properties](<code_reference/commandlets/show-bomwindow/objects/bom:bom properties>) and [Entity properties](<code_reference/commandlets/show-bomwindow/objects/item:entity properties>) can be attached and later [displayed as columns](<bom_window/customization:add or remove columns>) in the BOM Window.

When an exception is thrown within this function, the passed *\$bomHeader* element is [marked as failed](<bom_window:errors>) in the BOM Window.

## Examples

**Return a single BOM row with custom properties:**

```powershell
function Get-BomRows($bomHeader){
   if($bomHeader._Name -eq 'BomRow'){
      return @()
   }
   $bomRow = New-Object -TypeName PSObject -Property @{
      #Recommended properties
      _Name='BomRow'
      Bom_Quantity=10
      Bom_PositionNumber=1
      Bom_Number='BomRow'
      _Category='Part' #Additional entity property
      Bom_Unit='Each' #Additional BOM property
   }
   return @($bomRow)
}
```

**Return all BOM rows of a Vault Item:**

```powershell
function Get-BomRows($vaultItem) {
   $bomRows = Get-VaultItemBom -Number $vaultItem._Number
   $bomRows | foreach {
      if($vaultItem.Bom_RowOrder) {
         Add-Member -InputObject $_ -Name Bom_RowOrder -Value ("{0}.{1}" -f $vaultItem.Bom_RowOrder,$_.Bom_RowOrder) -MemberType NoteProperty -Force
      }
   }
   return $bomRows
}
```

**Return all BOM rows of a Vault file and warn about disabled Structured View:**

```powershell
function Get-BomRows($file) {
   $fileBom = Get-VaultFileBom -File $file._FullPath

   if(($fileBom | select -ExpandProperty 'Bom_PositionNumber' -Unique) -eq '') {
      throw "The BOM of file '$($file._Name)' contains $($fileBom.Count) rows without position number! Please checkout the file in Inventor, enable the Structured View and re-checkin the file to Vault!"
   }
   return $fileBom
}
```

**Return all BOM rows of a Vault Item or File, by handling purchased, virtual and non-master model state components:**

```powershell
function Get-BomRows($bomHeader) {
   if($bomHeader._EntityTypeID -notin 'ITEM','FILE') {        
      return @()    
   }
   if($bomHeader._EntityTypeID -eq "ITEM") {
      $bomRows = Get-VaultItemBom -Number $bomHeader._Number
   }
   if($bomHeader._EntityTypeID -eq "FILE") {
      if($bomHeader.Bom_Structure -eq 'Purchased') {
         return @()
      }
      $bomRows = Get-VaultFileBom -File $bomHeader._FullPath -ModelStateType $bomHeader.Bom_ModelState
   }

   foreach($bomRow in $bomRows) {
      if($null -eq $bomRow._EntityTypeID) {
         # Virtual components - have no file properties
         Add-Member -InputObject $bomRow -Name "BomType" -Value "Virtual" -MemberType NoteProperty -Force
      }       
      if($bomHeader.Bom_RowOrder) { 
         Add-Member -InputObject $bomRow -Name Bom_RowOrder -Value ("{0}.{1}" -f $bomHeader.Bom_RowOrder,$bomRow.Bom_RowOrder) -MemberType NoteProperty -Force        
      }
   }
   return $bomRows
}
```