fix dbcontext cleanup on failed add for sqlite

Author: georg-jung

WoL/Data/HostService.cs

@@ -5,6 +5,7 @@
 using System.Linq;
 using System.Text.RegularExpressions;
 using System.Threading.Tasks;
+using Microsoft.Data.Sqlite;
 using WoL.Models;
 
 namespace WoL.Data
@@ -13,11 +14,13 @@ public class HostService : IHostService
     {
         private readonly ApplicationDbContext context;
 
-        private static readonly Regex parseDuplicateValue = new Regex(@"The duplicate key value is \(([^)]+)\)");
-        private static readonly Regex parseIndexName = new Regex(@"with unique index '([^']+)'\.");
+        private static readonly Regex tsqlParseDuplicateValue = new Regex(@"The duplicate key value is \(([^)]+)\)");
+        private static readonly Regex tsqlParseIndexName = new Regex(@"with unique index '([^']+)'\.");
         // this makes assumptions about the names of the indices which is kind of bad
         // on the other hand it sticks to ef's index naming conventions
-        private static readonly Regex parseIdxField = new Regex(@"_([^_]+)$");
+        private static readonly Regex tsqlParseIdxField = new Regex(@"_([^_]+)$");
+
+        private static readonly Regex sqliteParseParseIdxField = new Regex(@"UNIQUE constraint failed: ([^']+)");
 
         public HostService(ApplicationDbContext context)
         {
@@ -37,20 +40,43 @@ public async Task Add(Host host)
                 await context.SaveChangesAsync().ConfigureAwait(false);
             }
             catch (DbUpdateException dbue)
-            // see https://docs.microsoft.com/en-us/sql/relational-databases/errors-events/database-engine-events-and-errors
-            // i.e. "Cannot insert duplicate key row in object 'dbo.Host' with unique index 'IX_Host_Hostname'. The duplicate key value is (georg-nuc). The statement has been terminated."
-            when (dbue.InnerException is SqlException sqlEx &&
-                  (sqlEx.Number == 2601 || sqlEx.Number == 2627))
+                // handle tsql
+                // see https://docs.microsoft.com/en-us/sql/relational-databases/errors-events/database-engine-events-and-errors
+                // i.e. "Cannot insert duplicate key row in object 'dbo.Host' with unique index 'IX_Host_Hostname'. The duplicate key value is (georg-nuc). The statement has been terminated."
+                when (dbue.InnerException is SqlException sqlEx &&
+                      (sqlEx.Number == 2601 || sqlEx.Number == 2627))
             {
                 // otherwise this host would be added again when further using the same DbContext
                 context.Entry(host).State = EntityState.Detached;
 
                 var msg = sqlEx.Message;
-                var duplVal = parseDuplicateValue.Match(msg).Groups[1].Value;
-                var idxName = parseIndexName.Match(msg).Groups[1].Value;
-                var fieldName = parseIdxField.Match(idxName).Groups[1].Value;
+                var duplVal = tsqlParseDuplicateValue.Match(msg).Groups[1].Value;
+                var idxName = tsqlParseIndexName.Match(msg).Groups[1].Value;
+                var fieldName = tsqlParseIdxField.Match(idxName).Groups[1].Value;
                 throw new IHostService.DuplicateEntryException(fieldName, duplVal, nameof(host), dbue);
             }
+            catch (DbUpdateException dbue)
+                // handle sqlite
+                // see https://sqlite.org/rescode.html
+                // i.e. "SQLite Error 19: 'UNIQUE constraint failed: Host.MacAddress'."
+                when (dbue.InnerException is SqliteException sqlEx &&
+                      (sqlEx.SqliteErrorCode == 19 || sqlEx.SqliteExtendedErrorCode == 2067))
+            {
+                // otherwise this host would be added again when further using the same DbContext
+                context.Entry(host).State = EntityState.Detached;
+
+                var msg = sqlEx.Message;
+                var fieldName = sqliteParseParseIdxField.Match(msg).Groups[1].Value;
+                if (fieldName.StartsWith("host.", StringComparison.OrdinalIgnoreCase))
+                    fieldName = fieldName.Substring(5);
+                throw new IHostService.DuplicateEntryException(fieldName, nameof(host), dbue);
+            }
+            catch
+            {
+                // otherwise this host would be added again when further using the same DbContext
+                context.Entry(host).State = EntityState.Detached;
+                throw;
+            }
         }
 
         public async Task Update(Host host)

WoL/Data/IHostService.cs

@@ -38,11 +38,19 @@ protected DuplicateEntryException(SerializationInfo info, StreamingContext conte
             private static string CreateMessage(string field, string value) =>
                 $"A host entry with {field} '{value}' does already exist.";
 
+            private static string CreateMessage(string field) =>
+                $"A host entry with the same {field} does already exist.";
+
             public DuplicateEntryException(string field, string value, string paramName, Exception innerException) : base(CreateMessage(field, value), paramName, innerException)
             {
                 Field = field;
                 Value = value;
             }
+
+            public DuplicateEntryException(string field, string paramName, Exception innerException) : base(CreateMessage(field), paramName, innerException)
+            {
+                Field = field;
+            }
         }
     }
 }

WoL/Pages/AddHost.razor

@@ -150,7 +150,9 @@
         catch (IHostService.DuplicateEntryException duplEx)
         {
             L.AddHostDuplicateEntryException(host, duplEx);
-            Alert = $"Creation failed as an entry with {duplEx.Field.ToLower()} '{duplEx.Value}' does already exists.";
+            Alert = string.IsNullOrEmpty(duplEx.Value)
+                ? $"Creation failed as an entry with this {duplEx.Field.ToLower()} does already exists."
+                : $"Creation failed as an entry with {duplEx.Field.ToLower()} '{duplEx.Value}' does already exists.";
             Creating = false;
             return;
         }