CSVHelper必填字段
本文关键字:字段 CSVHelper | 更新日期: 2023-09-27 18:28:50
解析csv文件时,如何定义特定字段是必需的。从本质上讲,我想确保给定的字段永远不会为空,如果为空,那么我希望抛出一个异常。这是映射类:
public sealed class DataMapper : CsvClassMap<DataType>
{
public DataMapper()
{
Map(m => m.Field1).Name("FirstField");
Map(m => m.Field2).Name("SecondField");
Map(m => m.Field3).Name("ThirdField"); // this field should be mandatory
}
}
以及用途:
List<DataType> data;
using (var sr = new StreamReader(localFilePath))
{
var reader = new CsvReader(sr);
reader.Configuration.RegisterClassMap<DataMapper>();
data = reader.GetRecords<DataType>().ToList();
}
目前我只是检查数据列表中的结果如下:
var numberOfInvalidRecords = data.Count(data => string.IsNullOrEmpty(data.Field3));
if (nullAccountHolderRecords > 0)
{
//handle
}
我在CSVHelper文档中找不到内置功能。我是不是错过了什么?
下面是一个扩展API的解决方案:
public static class CsvHelperExtensions
{
public static CsvPropertyMap Required<T>(this CsvPropertyMap map, string columnName)
{
return map.Name(columnName).ConvertUsing(row =>
{
if (string.IsNullOrEmpty(row.GetField(columnName)))
throw new CsvParserException($"{columnName} is required, but missing from row {row.Row}");
return row.GetField<T>(columnName);
});
}
}
用法:
public CsvPersonMap()
{
Map(m => m.FirstName).Required<string>("First");
Map(m => m.LastName).Name("Last");
Map(m => m.MiddleName).Required<string>("Middle");
}
我可能会使用ConvertUsing
扩展:
public sealed class DataMapper : CsvClassMap<DataType>
{
public DataMapper()
{
Map(m => m.Field1).Name("FirstField");
Map(m => m.Field2).Name("SecondField");
Map(m => m.Field3).ConvertUsing(row =>
{
if(string.IsNullOrEmpty(row.GetField<string>("ThirdField")))
throw new Exception("Oops, ThirdField is empty!");
return row.GetField<string>("ThirdField");
});
}
}
开发人员现在添加了一个Validate方法:https://joshclose.github.io/CsvHelper/examples/configuration/class-maps/validation
使用它来针对非null或空字符串进行验证:
Map(m => m.Id).Validate(field => !string.IsNullOrEmpty(field));
https://github.com/JoshClose/CsvHelper/issues/556
根据CsvHelper创建者的建议:
就目前而言,我想你必须WillThrowOnMissingField=false并运行一个循环并检查您的特定必填字段。你可能只需要在首读。
他的样本代码:
csv.WillThrowOnMissingField = false;
var list = new List<MyObject>();
var headerChecked = false;
while( csv.Read() )
{
if( !headerChecked )
{
// check for specific headers
if( !csv.FieldHeaders.Exists( "MyHeaderName" ) )
{
throw new Exception( "message" );
}
headerChecked = true;
}
list.Add( csv.GetRecord<MyObject>() );
}