Import-DbaCsv: Issue with scientific notification import to decimal fields

[mbentham]

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What error did you receive?

PSMessageDetails :
Exception : System.Exception: CSV parse error ---> System.Management.Automation.MethodInvocationException:
Exception calling "WriteToServer" with "1" argument(s): "CSV parse error" --->
Dataplat.Dbatools.Csv.CsvParseException: CSV parse error
at Dataplat.Dbatools.Csv.Reader.CsvDataReader.HandleParseError(Exception ex, String line)
in D:\a\dbatools.library\dbatools.library\project\dbatools\Csv\Reader\CsvDataReader.cs:line
1807
at Dataplat.Dbatools.Csv.Reader.CsvDataReader.ReadSequentialDirect() in
D:\a\dbatools.library\dbatools.library\project\dbatools\Csv\Reader\CsvDataReader.cs:line 1611
at Dataplat.Dbatools.Csv.Reader.CsvDataReader.Read() in
D:\a\dbatools.library\dbatools.library\project\dbatools\Csv\Reader\CsvDataReader.cs:line 1476
at Microsoft.Data.SqlClient.SqlBulkCopy.ReadFromRowSourceAsync(CancellationToken cts)
at Microsoft.Data.SqlClient.SqlBulkCopy.WriteToServerInternalAsync(CancellationToken ctoken)
at Microsoft.Data.SqlClient.SqlBulkCopy.WriteRowSourceToServerAsync(Int32 columnCount,
CancellationToken ctoken)
at Microsoft.Data.SqlClient.SqlBulkCopy.WriteToServer(IDataReader reader)
at CallSite.Target(Closure , CallSite , Object , Object )
--- End of inner exception stack trace ---
at System.Management.Automation.ExceptionHandlingOps.CheckActionPreference(FunctionContext
funcContext, Exception exception)
at System.Management.Automation.Interpreter.ActionCallInstruction`2.Run(InterpretedFrame
frame)
at
System.Management.Automation.Interpreter.EnterTryCatchFinallyInstruction.Run(InterpretedFrame
frame)
at
System.Management.Automation.Interpreter.EnterTryCatchFinallyInstruction.Run(InterpretedFrame
frame)
--- End of inner exception stack trace ---
TargetObject :
CategoryInfo : NotSpecified: (:) [], Exception
FullyQualifiedErrorId : dbatools_Import-DbaCsv
ErrorDetails :
InvocationInfo : System.Management.Automation.InvocationInfo
ScriptStackTrace : at Stop-Function, : line 102446
at Import-DbaCsv, : line 45233
at , : line 1
PipelineIterationInfo : {}

Steps to Reproduce

Create a table in SQL Server with a decimal column:

CREATE TABLE [dbo].[test](
	[id] [int] NULL,
	[data] decimal(18,6) NULL
)

Create a csv file with a scientific notation number:

id,data
1,1.2345678E5

Import the CSV to the created table using the Import-DbaCsv command

Import-DbaCsv -Path .\scientific_notification.txt -SqlInstance localhost -Database DBA -Table test -EnableException

Please confirm that you are running the most recent version of dbatools

2.7.13

Other details or mentions

In older dbatools versions where Import-Csv relied on the LumenWorks library this did not produce an error and would successfully convert the scientific-notation value into a decimal

What PowerShell host was used when producing this error

Windows PowerShell (powershell.exe)

PowerShell Host Version

Name Value

---

PSVersion 5.1.26100.7019
PSEdition Desktop
PSCompatibleVersions {1.0, 2.0, 3.0, 4.0...}
BuildVersion 10.0.26100.7019
CLRVersion 4.0.30319.42000
WSManStackVersion 3.0
PSRemotingProtocolVersion 2.3
SerializationVersion 1.1.0.1

SQL Server Edition and Build number

Microsoft SQL Server 2019 (RTM-CU32-GDR) (KB5068404) - 15.0.4455.2 (X64) Oct 7 2025 21:10:15 Copyright (C) 2019 Microsoft Corporation Enterprise Edition: Core-based Licensing (64-bit) on Windows Server 2022 Datacenter 10.0 (Build 20348: ) (Hypervisor)

.NET Framework Version

.NET Framework 4.8.4795.0

[potatoqualitee]

Thank you for the report. @mbentham ! @claude please review this error and consider other parser issues that may come up as well, and accommodate for them in a new PR.

[claude]

Claude finished @potatoqualitee's task in 2m 59s —— View job • claude/issue-35-20251210-0615 • Create PR ➔

---

Task completed

• Read repository setup instructions (CLAUDE.md)
• Understand the CSV parsing code and locate the issue
• Implement fix for scientific notation parsing
• Consider other numeric edge cases
• Build and test changes
• Commit and push changes
• Provide PR creation link

Issue identified

The DecimalConverter in NumericConverters.cs uses NumberStyles.Number which doesn't support scientific notation (exponent format like 1.2345678E5).

Meanwhile, SingleConverter and DoubleConverter use NumberStyles.Float | NumberStyles.AllowThousands, which includes the AllowExponent flag needed for scientific notation.

Changes made

1. Updated DecimalConverter (NumericConverters.cs:149)

   • Changed from NumberStyles.Number to NumberStyles.Float | NumberStyles.AllowThousands
   • This aligns decimal parsing with float/double converters
   • Updated XML documentation to mention scientific notation support

2. Added comprehensive tests (TypeConverterTest.cs:164-182)

   • Test case from issue Import-DbaCsv: Issue with scientific notification import to decimal fields #35: 1.2345678E5 → 123456.78
   • Positive exponents: 1.5e10 → 15000000000
   • Negative exponents: 2.5E-3 → 0.0025
   • Negative values: -3.14E2 → -314

Other edge cases considered

The NumberStyles.Float flag also handles:

• Infinity values: "Infinity", "-Infinity" (though decimal.TryParse will fail these, as decimal doesn't support infinity)
• Leading/trailing whitespace: Already handled by trimming options
• Culture-specific decimal separators: Already supported via ICultureAwareConverter
• Thousands separators: Enabled via AllowThousands flag

This fix ensures consistency across all numeric converters and restores compatibility with the old LumenWorks library behavior.

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