Power Query 忽略缺失列

Question

我创建了一个自定义函数来在强大的查询中转换文件：

let
    Source = (#"Sample File Parameter1" as binary) => let
    Source = Excel.Workbook(#"Sample File Parameter1", null, true),
    #"Sjælland m# kl# 1" = Source{[Name="Sjælland m# kl# 0"]}[Data],
    #"Removed Top Rows" = Table.Skip(#"Sjælland m# kl# 1",6),
    #"Promoted Headers" = Table.PromoteHeaders(#"Removed Top Rows", [PromoteAllScalars=true]),
    #"Changed Type" = Table.TransformColumnTypes(#"Promoted Headers",{{"Column1", type text}, {"LAB Nr", type text}, {"Column3", type text}, {"PrøveId", type text}, {"Dybde", type text}, {"Column6", type text}, {"Enhed", type text}, {"Klassificering", type text}, {"Bly (Pb)", type text}, {"Column10", type text}, {"Cadmium (Cd)", type text}, {"Chrom Total (Cr total)", type text}, {"Kobber (Cu)", type number}, {"Nikkel (Ni)", Int64.Type}, {"Zink (Zn)", Int64.Type}, {"Benzen", type text}, {"BTEX total", type text}, {"Benz(a)pyren", type text}, {"Dibenz(a,h)antracen", type text}, {"PAH total", type number}, {"Flygtige (Benzin) (C6-C10)", type text}, {"Let olie (C10-C15)", type text}, {"Let olie (C15-C20)", type text}, {"Tung olie (C20-C35)", type text}, {"Olie Total (C6-C35)", type text}}),
    #"Removed Other Columns" = Table.SelectColumns(#"Changed Type",{"PrøveId", "Dybde", "Bly (Pb)", "Cadmium (Cd)", "Chrom Total (Cr total)", "Kobber (Cu)", "Nikkel (Ni)", "Zink (Zn)", "Benzen", "BTEX total", "Benz(a)pyren", "Dibenz(a,h)antracen", "PAH total", "Flygtige (Benzin) (C6-C10)", "Let olie (C10-C15)", "Let olie (C15-C20)", "Tung olie (C20-C35)", "Olie Total (C6-C35)"}),
    #"Filtered Rows" = Table.SelectRows(#"Removed Other Columns", each ([#"Olie Total (C6-C35)"] <> null)),
    #"Added Custom" = Table.AddColumn(#"Filtered Rows", "Top", each Number.ToText(Number.FromText(Text.Start([Dybde],Text.PositionOf([Dybde],"-"))),"0.0")),
    #"Added Custom1" = Table.AddColumn(#"Added Custom", "Key", each [PrøveId]&"-"&[Top]),
    #"Removed Other Columns1" = Table.SelectColumns(#"Added Custom1",{"Bly (Pb)", "Cadmium (Cd)", "Chrom Total (Cr total)", "Kobber (Cu)", "Nikkel (Ni)", "Zink (Zn)", "Benzen", "BTEX total", "Benz(a)pyren", "Dibenz(a,h)antracen", "PAH total", "Flygtige (Benzin) (C6-C10)", "Let olie (C10-C15)", "Let olie (C15-C20)", "Tung olie (C20-C35)", "Olie Total (C6-C35)", "Key"}),
    #"Unpivoted Only Selected Columns" = Table.Unpivot(#"Removed Other Columns1", {"Bly (Pb)", "Cadmium (Cd)", "Chrom Total (Cr total)", "Kobber (Cu)", "Nikkel (Ni)", "Zink (Zn)", "Benzen", "BTEX total", "Benz(a)pyren", "Dibenz(a,h)antracen", "PAH total", "Flygtige (Benzin) (C6-C10)", "Let olie (C10-C15)", "Let olie (C15-C20)", "Tung olie (C20-C35)", "Olie Total (C6-C35)"}, "Attribute", "Value" )
in
    #"Unpivoted Only Selected Columns"
in
    Source

然后我运行以下查询对文件夹中的所有文件执行此操作：

let
    Source = Folder.Files(ResultsTable),
    #"Filtered Hidden Files1" = Table.SelectRows(Source, each [Attributes]?[Hidden]? <> true),
    #"Invoke Custom Function1" = Table.AddColumn(#"Filtered Hidden Files1", "Transform File from Analyseresultater", each #"Transform File from Analyseresultater"([Content])),
    #"Renamed Columns1" = Table.RenameColumns(#"Invoke Custom Function1", {"Name", "Source.Name"}),
    #"Removed Other Columns1" = Table.SelectColumns(#"Renamed Columns1", {"Source.Name", "Transform File from Analyseresultater"}),
    #"Expanded Table Column1" = Table.ExpandTableColumn(#"Removed Other Columns1", "Transform File from Analyseresultater", Table.ColumnNames(#"Transform File from Analyseresultater"(#"Sample File"))),
    #"Removed Other Columns" = Table.SelectColumns(#"Expanded Table Column1",{"Key", "Attribute", "Value"})
in
    #"Removed Other Columns"

我的问题是列 "Benzen" 和 "BTEX Total" 并不总是存在，所以我得到一个错误：

Expression.Error: The column 'Benzen' of the table wasn't found. Details: Benzen

我曾尝试使用 MissingField.Ignore og MissingField.UseNull 但没有成功，所以现在我转向 Whosebug 寻求帮助，有人可以帮我解决这个错误 :) 希望这是可能的

Answer 1

对于 Table.SelectColumns，您可以使用 MissingField.Ignore 参数，如您所述。由于 Table.TransformColumnTypes 函数返回的错误。最简单的解决方案 - 从中删除 {"Benzen", type text}, {"BTEX total", type text}, （我想，type text 对其他人来说不是必需的转换）。

Power Query 忽略缺失列

Power Query ignore missing column

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