Refactoring

AMWD.Common.EntityFrameworkCore/Extensions/ModelBuilderExtensions.cs

@@ -0,0 +1,162 @@
+using System.ComponentModel.DataAnnotations.Schema;
+using System.Reflection;
+using System.Text;
+using AMWD.Common.EntityFrameworkCore.Attributes;
+using Microsoft.EntityFrameworkCore;
+#if NET5_0_OR_GREATER
+using Microsoft.EntityFrameworkCore.Metadata;
+#endif
+
+namespace AMWD.Common.EntityFrameworkCore.Extensions
+{
+	/// <summary>
+	/// Extensions for the <see cref="ModelBuilder"/> of entity framework core.
+	/// </summary>
+	public static class ModelBuilderExtensions
+	{
+		/// <summary>
+		/// Applies indices and unique constraints to the properties.
+		/// </summary>
+		/// <param name="builder">The database model builder.</param>
+		/// <returns>A reference to this instance after the operation has completed.</returns>
+		[System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE0019", Justification = "No pattern comparison in this case due to readability.")]
+		public static ModelBuilder ApplyIndexAttributes(this ModelBuilder builder)
+		{
+			foreach (var entityType in builder.Model.GetEntityTypes())
+			{
+				foreach (var property in entityType.GetProperties())
+				{
+					var indexAttribute = entityType.ClrType
+						.GetProperty(property.Name)
+						?.GetCustomAttribute(typeof(DatabaseIndexAttribute), false) as DatabaseIndexAttribute;
+					if (indexAttribute != null)
+					{
+						var index = entityType.AddIndex(property);
+						index.IsUnique = indexAttribute.IsUnique;
+
+						if (!string.IsNullOrWhiteSpace(indexAttribute.Name))
+						{
+#if NET5_0_OR_GREATER
+							index.SetDatabaseName(indexAttribute.Name.Trim());
+#else
+							index.SetName(indexAttribute.Name.Trim());
+#endif
+						}
+					}
+				}
+			}
+
+			return builder;
+		}
+
+		/// <summary>
+		/// Converts all table and column names to snake_case_names.
+		/// </summary>
+		/// <param name="builder">The database model builder.</param>
+		/// <returns>A reference to this instance after the operation has completed.</returns>
+		public static ModelBuilder ApplySnakeCase(this ModelBuilder builder)
+		{
+			foreach (var entityType in builder.Model.GetEntityTypes())
+			{
+				// skip conversion when table name is explicitly set
+				if ((entityType.ClrType.GetCustomAttribute(typeof(TableAttribute), false) as TableAttribute) == null)
+				{
+#if NET5_0_OR_GREATER
+					entityType.SetTableName(ConvertToSnakeCase(entityType.GetTableName()));
+#else
+					entityType.SetTableName(ConvertToSnakeCase(entityType.GetTableName()));
+#endif
+				}
+
+#if NET5_0_OR_GREATER
+				var identifier = StoreObjectIdentifier.Table(entityType.GetTableName(), entityType.GetSchema());
+#endif
+				foreach (var property in entityType.GetProperties())
+				{
+					// skip conversion when column name is explicitly set
+					if ((entityType.ClrType.GetProperty(property.Name)?.GetCustomAttribute(typeof(ColumnAttribute), false) as ColumnAttribute) == null)
+					{
+#if NET5_0_OR_GREATER
+						property.SetColumnName(ConvertToSnakeCase(property.GetColumnName(identifier)));
+#else
+						property.SetColumnName(ConvertToSnakeCase(property.GetColumnName()));
+#endif
+					}
+				}
+			}
+
+			return builder;
+		}
+
+		/// <summary>
+		/// Converts a string to its snake_case equivalent.
+		/// </summary>
+		/// <remarks>
+		/// Code borrowed from Npgsql.NameTranslation.NpgsqlSnakeCaseNameTranslator.
+		/// See https://github.com/npgsql/npgsql/blob/f2b2c98f45df6d2a78eec00ae867f18944d717ca/src/Npgsql/NameTranslation/NpgsqlSnakeCaseNameTranslator.cs#L76-L136.
+		/// </remarks>
+		/// <param name="value">The value to convert.</param>
+		private static string ConvertToSnakeCase(string value)
+		{
+			var sb = new StringBuilder();
+			var state = SnakeCaseState.Start;
+
+			for (int i = 0; i < value.Length; i++)
+			{
+				if (value[i] == ' ')
+				{
+					if (state != SnakeCaseState.Start)
+						state = SnakeCaseState.NewWord;
+				}
+				else if (char.IsUpper(value[i]))
+				{
+					switch (state)
+					{
+						case SnakeCaseState.Upper:
+							bool hasNext = (i + 1 < value.Length);
+							if (i > 0 && hasNext)
+							{
+								char nextChar = value[i + 1];
+								if (!char.IsUpper(nextChar) && nextChar != '_')
+								{
+									sb.Append('_');
+								}
+							}
+							break;
+
+						case SnakeCaseState.Lower:
+						case SnakeCaseState.NewWord:
+							sb.Append('_');
+							break;
+					}
+
+					sb.Append(char.ToLowerInvariant(value[i]));
+					state = SnakeCaseState.Upper;
+				}
+				else if (value[i] == '_')
+				{
+					sb.Append('_');
+					state = SnakeCaseState.Start;
+				}
+				else
+				{
+					if (state == SnakeCaseState.NewWord)
+						sb.Append('_');
+
+					sb.Append(value[i]);
+					state = SnakeCaseState.Lower;
+				}
+			}
+
+			return sb.ToString();
+		}
+
+		private enum SnakeCaseState
+		{
+			Start,
+			Lower,
+			Upper,
+			NewWord
+		}
+	}
+}