feat(db): migration for ElementDataType + widen attribute Value to nvarchar(max) (idempotent)

src/ZB.MOM.WW.ScadaBridge.ConfigurationDatabase/Configurations/InstanceConfiguration.cs

@@ -99,8 +99,12 @@ public class InstanceAttributeOverrideConfiguration : IEntityTypeConfiguration<I
             .IsRequired()
             .HasMaxLength(200);
 
-        builder.Property(o => o.OverrideValue)
-            .HasMaxLength(4000);
+        // nvarchar(max): List attribute values (JSON arrays) can exceed 4000 chars.
+        builder.Property(o => o.OverrideValue);
+
+        builder.Property(o => o.ElementDataType)
+            .HasConversion<string>()
+            .HasMaxLength(50);
 
         builder.HasIndex(o => new { o.InstanceId, o.AttributeName }).IsUnique();
     }

src/ZB.MOM.WW.ScadaBridge.ConfigurationDatabase/Configurations/TemplateConfiguration.cs

@@ -108,8 +108,8 @@ public class TemplateAttributeConfiguration : IEntityTypeConfiguration<TemplateA
             .IsRequired()
             .HasMaxLength(200);
 
-        builder.Property(a => a.Value)
-            .HasMaxLength(4000);
+        // nvarchar(max): List attribute values (JSON arrays) can exceed 4000 chars.
+        builder.Property(a => a.Value);
 
         builder.Property(a => a.Description)
             .HasMaxLength(2000);
@@ -121,6 +121,10 @@ public class TemplateAttributeConfiguration : IEntityTypeConfiguration<TemplateA
             .HasConversion<string>()
             .HasMaxLength(50);
 
+        builder.Property(a => a.ElementDataType)
+            .HasConversion<string>()
+            .HasMaxLength(50);
+
         builder.HasIndex(a => new { a.TemplateId, a.Name }).IsUnique();
     }
 }

src/ZB.MOM.WW.ScadaBridge.ConfigurationDatabase/Migrations/20260616192131_AddListAttributeElementType.cs

@@ -0,0 +1,41 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace ZB.MOM.WW.ScadaBridge.ConfigurationDatabase.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddListAttributeElementType : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            // Idempotent DDL: every statement is guarded so this migration is safe
+            // to re-run against a partially-migrated DB (the #70 crash-loop lesson).
+            migrationBuilder.Sql(@"
+IF NOT EXISTS (SELECT 1 FROM sys.columns WHERE Name='ElementDataType' AND Object_ID=Object_ID('TemplateAttributes'))
+    ALTER TABLE [TemplateAttributes] ADD [ElementDataType] nvarchar(50) NULL;");
+            migrationBuilder.Sql(@"
+IF NOT EXISTS (SELECT 1 FROM sys.columns WHERE Name='ElementDataType' AND Object_ID=Object_ID('InstanceAttributeOverrides'))
+    ALTER TABLE [InstanceAttributeOverrides] ADD [ElementDataType] nvarchar(50) NULL;");
+            // ALTER COLUMN is naturally idempotent: re-running widens an already-widened column.
+            migrationBuilder.Sql("ALTER TABLE [TemplateAttributes] ALTER COLUMN [Value] nvarchar(max) NULL;");
+            migrationBuilder.Sql("ALTER TABLE [InstanceAttributeOverrides] ALTER COLUMN [OverrideValue] nvarchar(max) NULL;");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            // Idempotent reverse DDL: drop the new columns only if present, then
+            // restore the value columns to their original nvarchar(4000) width.
+            migrationBuilder.Sql(@"
+IF EXISTS (SELECT 1 FROM sys.columns WHERE Name='ElementDataType' AND Object_ID=Object_ID('TemplateAttributes'))
+    ALTER TABLE [TemplateAttributes] DROP COLUMN [ElementDataType];");
+            migrationBuilder.Sql(@"
+IF EXISTS (SELECT 1 FROM sys.columns WHERE Name='ElementDataType' AND Object_ID=Object_ID('InstanceAttributeOverrides'))
+    ALTER TABLE [InstanceAttributeOverrides] DROP COLUMN [ElementDataType];");
+            migrationBuilder.Sql("ALTER TABLE [TemplateAttributes] ALTER COLUMN [Value] nvarchar(4000) NULL;");
+            migrationBuilder.Sql("ALTER TABLE [InstanceAttributeOverrides] ALTER COLUMN [OverrideValue] nvarchar(4000) NULL;");
+        }
+    }
+}

src/ZB.MOM.WW.ScadaBridge.ConfigurationDatabase/Migrations/ScadaBridgeDbContextModelSnapshot.cs

@@ -563,12 +563,15 @@ namespace ZB.MOM.WW.ScadaBridge.ConfigurationDatabase.Migrations
                         .HasMaxLength(200)
                         .HasColumnType("nvarchar(200)");
 
+                    b.Property<string>("ElementDataType")
+                        .HasMaxLength(50)
+                        .HasColumnType("nvarchar(50)");
+
                     b.Property<int>("InstanceId")
                         .HasColumnType("int");
 
                     b.Property<string>("OverrideValue")
-                        .HasMaxLength(4000)
-                        .HasColumnType("nvarchar(4000)");
+                        .HasColumnType("nvarchar(max)");
 
                     b.HasKey("Id");
 
@@ -1164,6 +1167,10 @@ namespace ZB.MOM.WW.ScadaBridge.ConfigurationDatabase.Migrations
                         .HasMaxLength(2000)
                         .HasColumnType("nvarchar(2000)");
 
+                    b.Property<string>("ElementDataType")
+                        .HasMaxLength(50)
+                        .HasColumnType("nvarchar(50)");
+
                     b.Property<bool>("IsInherited")
                         .HasColumnType("bit");
 
@@ -1182,8 +1189,7 @@ namespace ZB.MOM.WW.ScadaBridge.ConfigurationDatabase.Migrations
                         .HasColumnType("int");
 
                     b.Property<string>("Value")
-                        .HasMaxLength(4000)
-                        .HasColumnType("nvarchar(4000)");
+                        .HasColumnType("nvarchar(max)");
 
                     b.HasKey("Id");