Refactor encoding handling in DbfDbConnection and DbfDbConnectionStringBuilder (#263)

Author: chrisrichards

README.md

@@ -131,7 +131,8 @@ The connection string supports the options available in `DbfDataReaderOptions`:
 - Encoding - the encoding to be used
   - optional
   - string
-  - valid Encoding name from [Encoding](https://learn.microsoft.com/en-us/dotnet/api/System.Text.Encoding)
+  - defaults to null and uses the language from the DBF header
+  - valid Encoding web name from [Encoding](https://learn.microsoft.com/en-us/dotnet/api/System.Text.Encoding) e.g. 'ascii'
 - ReadFloatsAsDecimals - whether to read floats as decimals
   - optional
   - boolean

src/DbfDataReader/DbfDbConnection.cs

@@ -2,6 +2,7 @@
 using System.Data;
 using System.Data.Common;
 using System.IO;
+using System.Text;
 
 namespace DbfDataReader
 {
@@ -54,9 +55,9 @@ public override void Open()
 
             var options = new DbfDataReaderOptions();
 
-            if (builder.Encoding is var encoding) 
+            if (builder.Encoding is { } encoding) 
             {
-                options.Encoding = encoding;
+                options.Encoding = Encoding.GetEncoding(encoding);
             }
 
             if (builder.ReadFloatsAsDecimals is var readFloatsAsDecimals)

src/DbfDataReader/DbfDbConnectionStringBuilder.cs

@@ -2,7 +2,6 @@
 using System.Collections.Generic;
 using System.Data.Common;
 using System.Diagnostics;
-using System.Text;
 
 namespace DbfDataReader
 {
@@ -25,7 +24,7 @@ private enum Keywords
         private static readonly string[] ValidKeywords = BuildValidKeywords();
         private static readonly Dictionary<string,Keywords> KeywordsHash = BuildKeywordsHash();
 
-        private Encoding _encoding;
+        private string _encoding;
         private string _folder = string.Empty;
         private bool _readFloatsAsDecimals;
         private bool _skipDeletedRecords = true;
@@ -57,7 +56,7 @@ public override object this[string keyword]
                     Keywords index = GetIndex(keyword);
                     switch (index)
                     {
-                        case Keywords.Encoding: Encoding = DbfDbConnectionStringBuilderUtil.ConvertToEncoding(keyword, value); break;
+                        case Keywords.Encoding: Encoding = DbfDbConnectionStringBuilderUtil.ConvertToString(value); break;
                         case Keywords.Folder: Folder = DbfDbConnectionStringBuilderUtil.ConvertToString(value); break;
                         case Keywords.ReadFloatsAsDecimals: ReadFloatsAsDecimals = DbfDbConnectionStringBuilderUtil.ConvertToBoolean(value); break;
                         case Keywords.SkipDeletedRecords: SkipDeletedRecords = DbfDbConnectionStringBuilderUtil.ConvertToBoolean(value); break;
@@ -74,12 +73,12 @@ public override object this[string keyword]
             }
         }
 
-        public Encoding Encoding
+        public string Encoding
         {
             get => _encoding;
             set
             {
-                SetEncodingValue(value);
+                SetValue(DbfDbConnectionStringKeywords.Encoding, value);
                 _encoding = value;
             }
         }
@@ -165,11 +164,6 @@ private void SetValue(string keyword, string value)
             base[keyword] = value;
         }
 
-        private void SetEncodingValue(Encoding value)
-        {
-            base[DbfDbConnectionStringKeywords.Encoding] = DbfDbConnectionStringBuilderUtil.EncodingToString(value);
-        }
-
         private void SetStringTrimmingValue(StringTrimmingOption value)
         {
             Debug.Assert(DbfDbConnectionStringBuilderUtil.IsValidStringTrimmingOptionValue(value), "Invalid value for StringTrimming");
@@ -206,7 +200,7 @@ private void Reset(Keywords index)
             switch(index)
             {
                 case Keywords.Encoding:
-                    _encoding = null;
+                    _encoding = string.Empty;
                     break;
                 case Keywords.Folder:
                     _folder = string.Empty;

test/DbfDataReader.Tests/DbfDbConnectionStringBuilderTests.cs

@@ -33,7 +33,7 @@ public void Should_parse_encoding()
         var builder = new DbfDbConnectionStringBuilder(connectionString);
 
         // Assert
-        builder.Encoding.ShouldBe(Encoding.GetEncoding(encoding));
+        builder.Encoding.ShouldBe(encoding);
     }
 
     [Fact]

test/DbfDataReader.Tests/DbfDbConnectionTests.cs

@@ -13,7 +13,7 @@ public class DbfDbConnectionTests
     public async Task Should_read_all_rows()
     {
         var dbConnection = new DbfDbConnection();
-        dbConnection.ConnectionString = $"Folder={FolderPath};SkipDeletedRecords=false";
+        dbConnection.ConnectionString = $"Folder={FolderPath};Encoding=ascii;SkipDeletedRecords=false";
         dbConnection.Open();
 
         var dbCommand = dbConnection.CreateCommand();
@@ -36,7 +36,7 @@ public async Task Should_read_all_rows()
     public async Task Should_skip_deleted_rows()
     {
         var dbConnection = new DbfDbConnection();
-        dbConnection.ConnectionString = $"Folder={FolderPath};SkipDeletedRecords=true";
+        dbConnection.ConnectionString = $"Folder={FolderPath};Encoding=ascii;SkipDeletedRecords=true";
         dbConnection.Open();
 
         var dbCommand = dbConnection.CreateCommand();