Where

• Filter with custom scriptblock by -FilterScript
• Filter by property by -Property
• Tons of overloads for binary operators for mimicking direct expression.

NOTE

Use ? or where alias for Where-Object

Filter By

• Property

# -Property is positional
gci -file | where -Property Exists

• Script block

# -FilterScript is positional
gci -file | where -FilterScript { $_.CreationTime -gt [DateTime]::Now.AddDays(-5) }

Expression-Like

Where-Object contains a lot of parameters to emulate expression-like syntax with -Property.

gci -file | where Extension -eq '.ps1'
# equivalent to 
gci -file | where { $_.Extension -eq '.ps1' }

Intrinsic Where

Intrinsic Where can be useful when performance matters, it provides a way to return early base on certain condition without consuming the whole iteration.

• First or Last items satisfy certain condition
• Skip until one satisfies the condition and return all remaining items(including the one satisfies)
• Return items until one not satisfies the condition(excluding the one satisfies)
• Split items into two collections, one contains items satisfied the condition, the another are items remained.

Where(scriptblock condition, WhereOperatorSelectionMode mode = 0, int? count)