Add -NoHeader parameter to ConvertTo-Csv and Export-Csv cmdlets (PowerShell#19108)

Author: ArmaanMcleod

src/Microsoft.PowerShell.Commands.Utility/commands/utility/CsvCommands.cs

@@ -72,6 +72,12 @@ public abstract class BaseCsvWritingCommand : PSCmdlet
         [Alias("UQ")]
         public QuoteKind UseQuotes { get; set; } = QuoteKind.Always;
 
+        /// <summary>
+        /// Gets or sets property that writes csv file with no headers.
+        /// </summary>
+        [Parameter]
+        public SwitchParameter NoHeader { get; set; }
+
         #endregion Command Line Parameters
 
         /// <summary>
@@ -301,7 +307,7 @@ protected override void ProcessRecord()
                 }
 
                 // write headers (row1: typename + row2: column names)
-                if (!_isActuallyAppending)
+                if (!_isActuallyAppending && !NoHeader.IsPresent)
                 {
                     if (NoTypeInformation == false)
                     {
@@ -727,16 +733,20 @@ protected override void ProcessRecord()
             if (_propertyNames == null)
             {
                 _propertyNames = ExportCsvHelper.BuildPropertyNames(InputObject, _propertyNames);
-                if (NoTypeInformation == false)
-                {
-                    WriteCsvLine(ExportCsvHelper.GetTypeString(InputObject));
-                }
 
-                // Write property information
-                string properties = _helper.ConvertPropertyNamesCSV(_propertyNames);
-                if (!properties.Equals(string.Empty))
+                if (!NoHeader.IsPresent)
                 {
-                    WriteCsvLine(properties);
+                    if (NoTypeInformation == false)
+                    {
+                        WriteCsvLine(ExportCsvHelper.GetTypeString(InputObject));
+                    }
+
+                    // Write property information
+                    string properties = _helper.ConvertPropertyNamesCSV(_propertyNames);
+                    if (!properties.Equals(string.Empty))
+                    {
+                        WriteCsvLine(properties);
+                    }
                 }
             }
 

test/powershell/Modules/Microsoft.PowerShell.Utility/ConvertTo-Csv.Tests.ps1

@@ -91,6 +91,11 @@ Describe "ConvertTo-Csv" -Tags "CI" {
         $result | Should -Not -Match ([regex]::Escape('#TYPE'))
     }
 
+    It "Does not include headers with -NoHeader" {
+        $result = $testObject | ConvertTo-Csv -NoHeader
+        $result | Should -BeExactly '"Hello","World"'
+    }
+
     It "Does not support -UseQuotes and -QuoteFields at the same time" {
         { $testObject | ConvertTo-Csv -UseQuotes Always -QuoteFields "TestFieldName" } |
             Should -Throw -ErrorId "CannotSpecifyQuoteFieldsAndUseQuotes,Microsoft.PowerShell.Commands.ConvertToCsvCommand"

test/powershell/Modules/Microsoft.PowerShell.Utility/Export-Csv.Tests.ps1

@@ -68,6 +68,21 @@ Describe "Export-Csv" -Tags "CI" {
         $results[0] | Should -Not -Match ([regex]::Escape("#TYPE"))
     }
 
+    It "Does not include headers with -NoHeader when exported and can imported with headers" {
+        $P1 | Export-Csv -Path $testCsv -NoHeader
+        $results = Get-Content -Path $testCsv
+        $results | Should -BeExactly '"first"'
+        $results = Import-Csv -Path $testCsv -Header "P1"
+        $results[0].P1 | Should -BeExactly "first"
+    }
+
+    It "Does not include headers when imported with headers and exported using -NoHeader" {
+        $P1 | Export-Csv -Path $testCsv
+        (Import-Csv -Path $testCsv) | Export-Csv -Path $testCsv -NoHeader
+        $results = Get-Content -Path $testCsv
+        $results | Should -BeExactly '"first"'
+    }
+
     It "Includes type information when -IncludeTypeInformation is supplied" {
         $testObject | Export-Csv -Path $testCsv -IncludeTypeInformation
         $results = Get-Content -Path $testCsv