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Cursor Agentandrmcrackan
5c5d1bd946
CsvHelper was only used to write headers and flat DTO rows in the csv
exports. The new internal writer reproduces its output byte-for-byte:
the delimiter is the culture's list separator, records end with CRLF,
fields containing the delimiter, quotes, newlines, or leading/trailing
spaces are quoted per RFC 4180, and values are formatted with the
culture. The [Name]/[Ignore] attributes it replaced are now two tiny
local attributes.
Verified byte-identical output against CsvHelper 33.1.0 for both
exporters in en-US, de-DE (';' delimiter), and invariant cultures, and
for a seeded 30-book demo library export before/after.
Co-authored-by: rmcrackan <rmcrackan@gmail.com>
105 lines
3.1 KiB
C#
105 lines
3.1 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Globalization;
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using System.IO;
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using System.Linq;
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using System.Reflection;
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namespace ApplicationServices;
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/// <summary>Column header for csv and xlsx export. Mirrors the CsvHelper attribute it replaced.</summary>
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[AttributeUsage(AttributeTargets.Property)]
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internal sealed class NameAttribute(params string[] names) : Attribute
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{
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public string[] Names { get; } = names;
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}
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/// <summary>Excludes a property from csv export. Mirrors the CsvHelper attribute it replaced.</summary>
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[AttributeUsage(AttributeTargets.Property)]
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internal sealed class IgnoreAttribute : Attribute { }
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/// <summary>
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/// Minimal write-only CSV serializer, output-compatible with the way this project used
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/// CsvHelper: the delimiter is the culture's list separator, records end with CRLF,
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/// fields containing the delimiter, quotes, newlines, or leading/trailing spaces are
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/// quoted per RFC 4180, and values are formatted with the culture. Columns are the
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/// public instance properties of each record's runtime type, in declaration order,
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/// honoring <see cref="NameAttribute"/> and <see cref="IgnoreAttribute"/>.
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/// </summary>
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internal sealed class CsvWriter(TextWriter writer, CultureInfo culture) : IDisposable
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{
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private readonly string delimiter = culture.TextInfo.ListSeparator;
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private readonly Dictionary<Type, List<(string Header, PropertyInfo Property)>> columnCache = new();
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private bool rowHasFields;
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public void WriteHeader(Type type)
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{
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foreach (var (header, _) in getColumns(type))
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writeField(header);
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}
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public void NextRecord()
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{
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writer.Write("\r\n");
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rowHasFields = false;
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}
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public void WriteRecords<T>(IEnumerable<T> records) where T : notnull
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{
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foreach (var record in records)
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{
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foreach (var (_, property) in getColumns(record.GetType()))
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writeField(toString(property.GetValue(record)));
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NextRecord();
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}
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}
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public void Dispose() => writer.Dispose();
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private void writeField(string field)
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{
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if (rowHasFields)
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writer.Write(delimiter);
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writer.Write(escape(field));
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rowHasFields = true;
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}
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private string escape(string field)
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{
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if (field.Length == 0)
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return field;
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var needsQuoting
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= field.Contains('"')
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|| field[0] == ' '
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|| field[^1] == ' '
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|| field.Contains(delimiter)
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|| field.Contains('\r')
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|| field.Contains('\n');
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return needsQuoting ? $"\"{field.Replace("\"", "\"\"")}\"" : field;
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}
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private string toString(object? value)
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=> value switch
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{
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null => "",
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string s => s,
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IFormattable formattable => formattable.ToString(null, culture),
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_ => value.ToString() ?? ""
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};
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private List<(string Header, PropertyInfo Property)> getColumns(Type type)
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{
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if (!columnCache.TryGetValue(type, out var columns))
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columnCache[type] = columns = type
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.GetProperties(BindingFlags.Public | BindingFlags.Instance)
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.Where(p => p.GetMethod is not null
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&& p.GetIndexParameters().Length == 0
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&& p.GetCustomAttribute<IgnoreAttribute>() is null)
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.Select(p => (p.GetCustomAttribute<NameAttribute>()?.Names.FirstOrDefault() ?? p.Name, p))
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.ToList();
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return columns;
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}
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}
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