How to initialize an array of custom objects

Question

First  as this leads to my question  I ll start by noting that I ve worked with XML a fair bit in PowerShell  and like how I can read data from XML files  quickly  into arrays of custom objects  For example  if I had the following XML file    lt stuff gt    lt item name  Joe  age  32  gt     lt info gt something about him lt  info gt    lt  item gt    lt item name  Sue  age  29  gt     lt info gt something about her lt  info gt    lt  item gt    lt item name  Cat  age  12  gt     lt info gt something else lt  info gt    lt  item gt   lt  stuff gt    And if I read it in simply  like this    xml  myxml   Get-Content   my xml   Then I can get to an array of my items like this    array  myitems    myxml stuff Item  myitems  name   age  info ----   ---  ---- Joe    32   something about him Sue    29   something about her Cat    12   something else   So  now my question   How can I create a similar structure of an array of custom objects  and initialize them in my script  without reading a file   I can do lots of looping and or lots of creating initializing individual objects  and then add to an array one at a time     But it seems there should be a way to perform this creation initialization in a simpler way   Note that the key here  is that my custom objects have more than two elements  otherwise  I d have used a hash    I ve even looked at creating a big string of XML  and using Select-XML  but I just couldn t get the syntax right  if that was even the right road to be heading down

User · Answer

Use a  Here-String  and cast to XML    xml  myxml       lt stuff gt    lt item name  Joe  age  32  gt     lt info gt something about him lt  info gt    lt  item gt    lt item name  Sue  age  29  gt     lt info gt something about her lt  info gt    lt  item gt    lt item name  Cat  age  12  gt     lt info gt something else lt  info gt    lt  item gt   lt  stuff gt       array  myitems    myxml stuff Item   myitems

User · Answer

Maybe you mean like this  I like to make an object and use Format-Table   gt   array        gt   object   New-Object -TypeName PSObject  gt   object   Add-Member -Name  Name  -MemberType Noteproperty -Value  Joe   gt   object   Add-Member -Name  Age  -MemberType Noteproperty -Value 32  gt   object   Add-Member -Name  Info  -MemberType Noteproperty -Value  something about him   gt   array     object  gt   array   Format-Table  Name                                                                        Age Info ----                                                                        --- ---- Joe                                                                          32  something about him  This will put all objects you have in the array in columns according to their properties  Tip  Using -auto sizes the table better  gt   array   Format-Table -Auto  Name Age Info ---- --- ---- Joe   32 something about him  You can also specify which properties you want in the table  Just separate each property name with a comma   gt   array   Format-Table Name  Age -Auto  Name Age ---- --- Joe   32

User · Answer

A little variation on classes   Initialize it with hashtables   class Point    x   y     a    Point        x 1  y 2      x 3  y 4      a  x y         - -           1 2 3 4   a gettype    IsPublic IsSerial Name                                     BaseType -------- -------- ----                                     -------- True     True     Point                                    System Array   a 0  gettype    IsPublic IsSerial Name                                     BaseType -------- -------- ----                                     -------- True     False    Point                                    System Object

User · Answer

The simplest way to initialize an array  Create array   array         Create your header   line        select name age phone   Fill the line   line name    Leandro   line age    39   line phone    555-555555    Add line to  array   array     line   Result   array  name                                                     age                                                      phone ----                                                     ---                                                      ----- Leandro                                                  39                                                       555-555555

User · Answer

Here is a more concise version of the accepted answer which avoids repeating the NoteProperty identifiers and the  pscustomobject -cast    myItems      Joe  32  something about him      Sue  29  something about her                 ForEach-Object   pscustomobject   name      0   age      1   info      2      Result    gt   myItems  name           age         info ----           ---         ---- Joe            32          something about him Sue            29          something about her

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I d do something along these lines    myitems      pscustomobject   name  Joe  age 32 info  something about him     pscustomobject   name  Sue  age 29 info  something about her     pscustomobject   name  Cat  age 12 info  something else      Note that this only works in PowerShell 3  but since you did not mention the version in your question I m assuming this does not matter for you   Update  It has been mentioned in comments that if you do the following    younger    myitems   Where-Object      age -lt 20    Write-Host  people younger than 20     younger Length      You won t get 1 as you might expect  This happens when a single pscustomobject is returned  Now this is not a problem for most of other objects in PowerShell  because they have surrogate properties for Length and Count  Unfortunately pscustomobject does not  This is fixed in PowerShell 6 1 0  You can work around this by using operator        younger      myitems   Where-Object      age -lt 20      For more background see here and here   Update 2  In PowerShell 5 one can use Classes to acheive similar functionality  For example you can define a class like this   class Person        string  name      int  age      string  info          Person       string  name       int  age       string  info                 this name    name          this age    age          this info    info           Backticks here are so that you could copy and paste it to the command line  they are not required in a script  Once the class is defined you can the create an array the usual way    myitems     Person   new  Joe  32  something about him     Person   new  Sue  29  something about her     Person   new  Cat  12  something else      Note that this way does not have the drawback mentioned in the previous update  even in PowerShell 5   Update 3  You can also intialize a class object with a hashtable  similar to the first example  For that you need to make sure that a default contructor defined  If you do not provide any constructors  one will be created for you  but if you provide a non-default one  default constructor won t be there and you will need to define it explicitly  Here is an example with default constructor that is auto-created   class Person        string  name      int  age      string  info      With that you can    person      Person   name  Kevin  age 36 info  something about him    Person   name  Sue  age 29 info  something about her    Person   name  Cat  age 12 info  something else      This is a bit more verbose  but also a bit more explicit  Thanks to  js2010 for pointing this out

User · Answer

Here is a concise way to initialize an array of custom objects in PowerShell    gt   body         Prop1  1   Prop2  2   Prop3  3        Prop1  1   Prop2  2   Prop3  3       gt   body  Name                           Value ----                           ----- Prop2                          2 Prop1                          1 Prop3                          3 Prop2                          2 Prop1                          1 Prop3                          3

User · Answer

I had to create an array of a predefined type  and I successfully did as follows    System Data DataColumn    myitems     System Data DataColumn   col1                      System Data DataColumn   col2      System Data DataColumn   col3

User · Answer

Given the data above  this is how I would do it     initialize the array  PsObject    people          populate the array with each object  people     PsObject    Name    Joe   Age   32  Info    something about him     people     PsObject    Name    Sue   Age   29  Info    something about her     people     PsObject    Name    Cat   Age   12  Info    something else      The below code will work even if you only have 1 item after a Where-Object     display all people Write-Host  People   foreach  person in  people        Write-Host    - Name      person Name    Age     person Age   Info      person Info         display with just 1 person  length will be empty if using  PSCustomObject   so you have to wrap any results in a       as described by Andrew Savinykh in his updated answer   youngerPeople    people   Where-Object      Age -lt 20   Write-Host  People younger than 20     youngerPeople Length   foreach  youngerPerson in  youngerPeople        Write-Host    - Name      youngerPerson Name        Result   People    - Name   Joe   Age  32  Info   something about him    - Name   Sue   Age  29  Info   something about her    - Name   Cat   Age  12  Info   something else  People younger than 20  1   - Name   Cat

[powershell] How to initialize an array of custom objects

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