FileHelpers没有使用正确的日期格式

Question

我试图用DateTime字段解析记录，但是FileHelpers没有使用我提供的格式。下面是一个应该解析记录但引发错误的F#脚本。我认为这个问题与它是F#脚本有关，因为当我在.fsproj中使用它并与dotnet run一起运行它时，这段代码可以工作。

#r "nuget: FileHelpers, 3.5.1"

open System
open FileHelpers

[<DelimitedRecord(","); IgnoreFirst; CLIMutable>]
type RateRecord =
    {
        [<FieldConverter(ConverterKind.Date, "yyyy-MM-dd hh:mm")>]
        DateTime : DateTime
        Value : float
    }
  
let sampleData = """DateTime,Value
2020-02-01 00:00,259
2020-02-01 00:01,267
2020-02-01 00:02,270"""

let engine = FileHelperEngine<RateRecord>()
let values = engine.ReadString sampleData

运行脚本的输出。错误消息在末尾。注意，错误消息说它试图使用'ddMMyyyy'格式，这不是我指定的格式。

> #r "nuget: FileHelpers, 3.5.1"
-
- open System
- open FileHelpers
-
- [<DelimitedRecord(","); IgnoreFirst; CLIMutable>]
- type RateRecord =
-     {
-         [<FieldConverter(ConverterKind.Date, "yyyy-MM-dd hh:mm")>]
-         DateTime : DateTime
-         Value : float
-     }
-
-
- let sampleData = """DateTime,Value
- 2020-02-01 00:00,259
- 2020-02-01 00:01,267
- 2020-02-01 00:02,270"""
-
- let engine = FileHelperEngine<RateRecord>()
- let values = engine.ReadString sampleData
- ;;
[Loading C:\Users\mcrews\AppData\Local\Temp\22000--4251218c-2322-40be-9ae7-fce17ffe54c3\Project.fsproj.fsx]
namespace FSI_0012.Project

FileHelpers.ConvertException: Error Converting '2020-02-01 00:00' to type: 'DateTime'.  There are more chars in the Input String than in the Format string: 'ddMMyyyy'
   at FileHelpers.Converters.DateTimeConverter.StringToField(String from)
   at FileHelpers.FieldBase.AssignFromString(ExtractedInfo fieldString, LineInfo line)
   at FileHelpers.FieldBase.ExtractFieldValue(LineInfo line)
   at FileHelpers.RecordOperations.StringToRecord(Object record, LineInfo line, Object[] values)
   at FileHelpers.FileHelperEngine`1.ReadStreamAsList(TextReader reader, Int32 maxRecords, DataTable dt)
   at FileHelpers.FileHelperEngine`1.ReadStream(TextReader reader, Int32 maxRecords)
   at FileHelpers.FileHelperEngine`1.ReadString(String source, Int32 maxRecords)
   at FileHelpers.FileHelperEngine`1.ReadString(String source)
   at <StartupCode$FSI_0013>.$FSI_0013.main@() in d:\Documents\GitHub\Scratchpad\FileHelpers\Test.fsx:line 158
Stopped due to error
>

Answer 1

看起来，这与F#交互中对F#核心的支持有关。假设您使用的是Visual，如果在Tools > Options中关闭“使用.NET核心脚本”，脚本将按预期工作：

​

​

输出：

Microsoft (R) F# Interactive version 12.0.4.0 for F# 6.0
Copyright (c) Microsoft Corporation. All Rights Reserved.

...

val values: RateRecord[] =
  [|{ DateTime = 2/1/2020 12:00:00 AM
      Value = 259.0 }; { DateTime = 2/1/2020 12:01:00 AM
                         Value = 267.0 }; { DateTime = 2/1/2020 12:02:00 AM
                                            Value = 270.0 }|]

问题是当启用FieldConverter核心脚本时，.NET属性将被忽略。我猜想这在某种程度上是由FileHelpers构建的方式和/或.NET核心脚本中的问题造成的，这导致了反映错误行为(可能是不同版本的.NET之间的组装格式中微妙的不兼容)，但我不能肯定。如果我学到更多的话会更新。