Provide ToString implementation of ConnectionString

LiteDB.Tests/Database/ConnectionString_Tests.cs

@@ -26,12 +26,12 @@ public void ConnectionString_Parser()
 
             // file with spaces with " and ;
             var full = new ConnectionString(
-                @"filename=""c:\only;file\""d\""emo.db""; 
+                @"filename=""c:\only;file\""d\""e=mo.db""; 
                   password =   ""john-doe "" ;
                   initial size = 10 MB ;
                   readONLY =  TRUE;");
 
-            full.Filename.Should().Be(@"c:\only;file""d""emo.db");
+            full.Filename.Should().Be(@"c:\only;file""d""e=mo.db");
             full.Password.Should().Be("john-doe ");
             full.ReadOnly.Should().BeTrue();
             full.InitialSize.Should().Be(10 * 1024 * 1024);
@@ -47,5 +47,43 @@ public void ConnectionString_Very_Long()
             cn.Password.Length.Should().Be(512);
 
         }
+
+        [Fact]
+        public void ConnectionString_ToString()
+        {
+            var empty = new ConnectionString();
+
+            empty.ToString().Should().BeEmpty();
+
+            var onlyfile = new ConnectionString
+            {
+                Filename = @"c:\only file\demo.db",
+            };
+
+            onlyfile.ToString().Should().Be(@"c:\only file\demo.db");
+
+            // filename with =
+            var fileWithSpecials = new ConnectionString
+            {
+                Filename = @"c:\only file\d""e=mo.db",
+            };
+
+            fileWithSpecials.ToString().Should().Be(@"Filename=""c:\only file\d\""e=mo.db""");
+
+            // file with spaces with " and ;
+            var full = new ConnectionString
+            {
+                Filename = @"c:\only;file""d""emo.db",
+                Password = "john-doe ",
+                ReadOnly = true,
+                InitialSize = 10_485_760,
+            };
+
+            full.ToString().Should().Be(@"Filename=""c:\only;file\""d\""emo.db"";Password=""john-doe "";Initial Size=10485760;ReadOnly=True");
+
+            // ToString/Parse round trips
+            var parsed = new ConnectionString(full.ToString());
+            parsed.Should().BeEquivalentTo(full);
+        }
     }
-}
+}

LiteDB/Client/Structures/ConnectionString.cs

@@ -2,7 +2,7 @@
 using System;
 using System.Collections.Generic;
 using System.Globalization;
-using static LiteDB.Constants;
+using System.Text;
 
 namespace LiteDB
 {
@@ -136,5 +136,119 @@ internal ILiteEngine CreateEngine(Action<EngineSettings> engineSettingsAction =
                 throw new NotImplementedException();
             }
         }
+
+        /// <inheritdoc />
+        public override string ToString()
+        {
+            if (string.IsNullOrEmpty(Filename))
+            {
+                return string.Empty;
+            }
+
+            var bld = new StringBuilder("Filename=");
+            AppendQuotedString(bld, Filename);
+            bld.Append(';');
+
+            var fileNameLength = bld.Length;
+
+            if (Connection != ConnectionType.Direct)
+            {
+                bld.Append("Connection=")
+                    .Append(Connection)
+                    .Append(';');
+            }
+
+            if (Password != null)
+            {
+                bld.Append("Password=");
+                AppendQuotedString(bld, Password);
+                bld.Append(';');
+            }
+
+            if (InitialSize != 0)
+            {
+                bld.Append("Initial Size=")
+                    .AppendFormat(CultureInfo.InvariantCulture, "{0:D}", InitialSize)
+                    .Append(';');
+            }
+
+            if (ReadOnly)
+            {
+                bld.Append("ReadOnly=")
+                    .Append(ReadOnly)
+                    .Append(';');
+            }
+
+            if (Collation != null)
+            {
+                bld.Append("Collation=")
+                    .Append(Collation.Culture.Name)
+                    .Append('/');
+
+                foreach (CompareOptions option in Enum.GetValues(typeof(CompareOptions)))
+                {
+                    if (option != CompareOptions.None && Collation.SortOptions.HasFlag(option))
+                    {
+                        bld.Append(option)
+                            .Append(',');
+                    }
+                }
+
+                if (bld[bld.Length - 1] == '/')
+                {
+                    bld.Append("None");
+                }
+                else
+                {
+                    bld.Length--; //,
+                }
+
+                bld.Append(';');
+            }
+
+            if (Upgrade)
+            {
+                bld.Append("Upgrade=")
+                    .Append(Upgrade)
+                    .Append(';');
+            }
+
+            if (AutoRebuild)
+            {
+                bld.Append("Auto-Rebuild=")
+                    .Append(AutoRebuild)
+                    .Append(';');
+            }
+
+            if (bld.Length == fileNameLength && !Filename.Contains("="))
+            {
+                return Filename;
+            }
+
+            bld.Length--; // ;
+            return bld.ToString();
+        }
+
+        private static void AppendQuotedString(StringBuilder target, string str)
+        {
+            if (string.IsNullOrEmpty(str))
+            {
+                return;
+            }
+
+            target.Append('"');
+
+            foreach (var chr in str)
+            {
+                if (chr is '"')
+                {
+                    target.Append('\\');
+                }
+
+                target.Append(chr);
+            }
+
+            target.Append('"');
+        }
     }
-}
+}