René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"CSV deserialization outputs nothing if there are only a certain number of empty fields","articleBody":"### Prerequisites\n\n- [X] Write a descriptive title.\n- [X] Make sure you are able to repro it on the [latest released version](https://github.com/PowerShell/PowerShell/releases)\n- [X] Search the existing issues.\n- [X] Refer to the [FAQ](https://github.com/PowerShell/PowerShell/blob/master/docs/FAQ.md).\n- [X] Refer to [Differences between Windows PowerShell 5.1 and PowerShell](https://learn.microsoft.com/powershell/scripting/whats-new/differences-from-windows-powershell).\n\nIf CSV input data doesn't satisfy an uncommunicated threshold regarding the number of columns and empty quoted/unquoted fields, CSV deserialization using `ConvertFrom-Csv`/`Import-Csv` yields no output. No error/warning is emitted either; the input is effectively ignored.\n\n### Steps to reproduce\n\n#### Test 1\n\nIn the following examples, no custom object is emitted by `ConvertFrom-Csv` irrespective of row count.\n\n```powershell\n# No custom object output, irrespective of row count.\n\n# Example 1a:\n@'\n\"P1\"\n\"\"\n'@ | ConvertFrom-Csv\n\n# Example 1b:\n@'\n\"P1\"\n\"\"\n\"\"\n\"\"\n'@ | ConvertFrom-Csv\n```\n\n#### Tests 2-3\n\nIn the following examples, a custom object is emitted for all rows _except the last_.\n\n```powershell\n# Partial custom object output. \n# Output for each row except the last.\n# If there is only one row, no object is emitted.\n\n# Example 2a:\n@'\n\"P1\",\"P2\"\n\"\",\n'@ | ConvertFrom-Csv # Nothing\n\n# Example 2b:\n@'\n\"P1\",\"P2\"\n\"\",\n\"\",\n'@ | ConvertFrom-Csv # 1 custom object\n\n# Example 3a:\n@'\n\"P1\",\"P2\"\n,\n'@ | ConvertFrom-Csv # Nothing\n\n# Example 3b:\n@'\n\"P1\",\"P2\"\n,\n,\n'@ | ConvertFrom-Csv # 1 custom object\n```\n\n#### Tests 4-6\n\nCustom object output is **correct** in following examples.\n\n```powershell\n# Custom object output in examples 4-6.\n\n# Example 4a:\n@'\n\"P1\",\"P2\"\n,\"\"\n'@ | ConvertFrom-Csv\n\n# Example 4b:\n@'\n\"P1\",\"P2\"\n,\"\"\n,\"\"\n'@ | ConvertFrom-Csv\n\n# Example 5a:\n@'\n\"P1\",\"P2\"\n\"\",\"\"\n'@ | ConvertFrom-Csv\n\n# Example 5b:\n@'\n\"P1\",\"P2\"\n\"\",\"\"\n\"\",\"\"\n'@ | ConvertFrom-Csv\n\n# Example 6a:\n@'\n\"P1\",\"P2\",\"P3\"\n,,\n'@ | ConvertFrom-Csv\n\n# Example 6b:\n@'\n\"P1\",\"P2\",\"P3\"\n,,\n,,\n'@ | ConvertFrom-Csv\n```\n\nNote:\n- As of PS v7.5.0, the CSV data above (examples 1-6) is all generated by `ConvertTo-Csv`, which may produce quoted (`\"\"`) _or_ unquoted empty fields by default. See: \n    - https://github.com/PowerShell/PowerShell/issues/24699 \n- How `ConvertFrom-Csv` interprets unquoted empty fields is also inconsistent. See:\n    - https://github.com/PowerShell/PowerShell/issues/17702\n\n### Expected behavior\n\n- Test 1: Should emit a custom object with a `P1` property.\n- Tests 2a \u0026 3a: Should emit a custom object with a `P1` and `P2` property.\n- Tests 2b \u0026 3b: Should emit 2 custom objects, each with a `P1` and `P2` property.\n\n### Actual behavior\n\n- Test 1: No custom object output.\n- Tests 2-3: Partial custom object output for all rows except the last.\n\n### Environment data\n\n```powershell\nName                           Value\n----                           -----\nPSVersion                      7.5.0-rc.1\nPSEdition                      Core\nGitCommitId                    7.5.0-rc.1\nOS                             Microsoft Windows 10.0.19045\nPlatform                       Win32NT\nPSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}\nPSRemotingProtocolVersion      2.3\nSerializationVersion           1.1.0.1\nWSManStackVersion              3.0\n```","author":{"url":"https://github.com/surfingoldelephant","@type":"Person","name":"surfingoldelephant"},"datePublished":"2024-12-22T18:12:46.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":8},"url":"https://github.com/24698/PowerShell/issues/24698"}