Refactor UpdateSqlGenerator to separate select logic

src/EFCore.Relational/Update/SelectingUpdateSqlGenerator.cs

@@ -0,0 +1,308 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Text;
+
+namespace Microsoft.EntityFrameworkCore.Update;
+
+/// <summary>
+/// <para>
+/// A base class for the <see cref="IUpdateSqlGenerator" /> service that is typically inherited from by database providers.
+/// The implementation uses a separate SELECT query after the update SQL to retrieve any database-generated values or for
+/// concurrency checking.
+/// </para>
+/// <para>
+/// This type is typically used by database providers; it is generally not used in application code.
+/// </para>
+/// </summary>
+/// <remarks>
+/// <para>
+/// The service lifetime is <see cref="ServiceLifetime.Singleton" />. This means a single instance is used by many
+/// <see cref="DbContext" /> instances. The implementation must be thread-safe. This service cannot depend on services registered
+/// as <see cref="ServiceLifetime.Scoped" />.
+/// </para>
+/// <para>
+/// See <see href="https://aka.ms/efcore-docs-providers">Implementation of database providers and extensions</see> for more
+/// information and examples.
+/// </para>
+/// </remarks>
+public abstract class SelectingUpdateSqlGenerator : UpdateSqlGenerator
+{
+ /// <summary>
+ /// Initializes a new instance of the this class.
+ /// </summary>
+ /// <param name="dependencies">Parameter object containing dependencies for this service.</param>
+ protected SelectingUpdateSqlGenerator(UpdateSqlGeneratorDependencies dependencies)
+ : base(dependencies)
+ {
+ }
+
+ /// <inheritdoc />
+ public override ResultSetMapping AppendInsertOperation(
+ StringBuilder commandStringBuilder,
+ IReadOnlyModificationCommand command,
+ int commandPosition,
+ out bool requiresTransaction)
+ => AppendInsertAndSelectOperations(commandStringBuilder, command, commandPosition, out requiresTransaction);
+
+ /// <summary>
+ /// Appends SQL for inserting a row to the commands being built, via an INSERT followed by an optional SELECT to retrieve any
+ /// database-generated values.
+ /// </summary>
+ /// <param name="commandStringBuilder">The builder to which the SQL should be appended.</param>
+ /// <param name="command">The command that represents the delete operation.</param>
+ /// <param name="commandPosition">The ordinal of this command in the batch.</param>
+ /// <param name="requiresTransaction">Returns whether the SQL appended must be executed in a transaction to work correctly.</param>
+ /// <returns>The <see cref="ResultSetMapping" /> for the command.</returns>
+ protected virtual ResultSetMapping AppendInsertAndSelectOperations(
+ StringBuilder commandStringBuilder,
+ IReadOnlyModificationCommand command,
+ int commandPosition,
+ out bool requiresTransaction)
+ {
+ var name = command.TableName;
+ var schema = command.Schema;
+ var operations = command.ColumnModifications;
+
+ var writeOperations = operations.Where(o => o.IsWrite).ToList();
+ var readOperations = operations.Where(o => o.IsRead).ToList();
+
+ AppendInsertCommand(commandStringBuilder, name, schema, writeOperations, readOperations: Array.Empty<IColumnModification>());
+
+ if (readOperations.Count > 0)
+ {
+ var keyOperations = operations.Where(o => o.IsKey).ToList();
+
+ requiresTransaction = true;
+
+ return AppendSelectAffectedCommand(commandStringBuilder, name, schema, readOperations, keyOperations, commandPosition);
+ }
+
+ requiresTransaction = false;
+
+ return AppendSelectAffectedCountCommand(commandStringBuilder, name, schema, commandPosition);
+ }
+
+ /// <inheritdoc />
+ public override ResultSetMapping AppendUpdateOperation(
+ StringBuilder commandStringBuilder,
+ IReadOnlyModificationCommand command,
+ int commandPosition,
+ out bool requiresTransaction)
+ => AppendUpdateAndSelectOperation(commandStringBuilder, command, commandPosition, out requiresTransaction);
+
+ /// <summary>
+ /// Appends SQL for updating a row to the commands being built, via an UPDATE followed by a SELECT to retrieve any
+ /// database-generated values or for concurrency checking.
+ /// </summary>
+ /// <param name="commandStringBuilder">The builder to which the SQL should be appended.</param>
+ /// <param name="command">The command that represents the delete operation.</param>
+ /// <param name="commandPosition">The ordinal of this command in the batch.</param>
+ /// <param name="requiresTransaction">Returns whether the SQL appended must be executed in a transaction to work correctly.</param>
+ /// <returns>The <see cref="ResultSetMapping" /> for the command.</returns>
+ protected virtual ResultSetMapping AppendUpdateAndSelectOperation(
+ StringBuilder commandStringBuilder,
+ IReadOnlyModificationCommand command,
+ int commandPosition,
+ out bool requiresTransaction)
+ {
+ var name = command.TableName;
+ var schema = command.Schema;
+ var operations = command.ColumnModifications;
+
+ var writeOperations = operations.Where(o => o.IsWrite).ToList();
+ var conditionOperations = operations.Where(o => o.IsCondition).ToList();
+ var readOperations = operations.Where(o => o.IsRead).ToList();
+
+ AppendUpdateCommand(commandStringBuilder, name, schema, writeOperations, Array.Empty<IColumnModification>(), conditionOperations);
+
+ if (readOperations.Count > 0)
+ {
+ var keyOperations = operations.Where(o => o.IsKey).ToList();
+
+ requiresTransaction = true;
+
+ return AppendSelectAffectedCommand(commandStringBuilder, name, schema, readOperations, keyOperations, commandPosition);
+ }
+
+ requiresTransaction = false;
+
+ return AppendSelectAffectedCountCommand(commandStringBuilder, name, schema, commandPosition);
+ }
+
+ /// <inheritdoc />
+ public override ResultSetMapping AppendDeleteOperation(
+ StringBuilder commandStringBuilder,
+ IReadOnlyModificationCommand command,
+ int commandPosition,
+ out bool requiresTransaction)
+ => AppendDeleteAndSelectOperation(commandStringBuilder, command, commandPosition, out requiresTransaction);
+
+ /// <summary>
+ /// Appends SQL for updating a row to the commands being built, via a DELETE followed by a SELECT for concurrency checking.
+ /// </summary>
+ /// <param name="commandStringBuilder">The builder to which the SQL should be appended.</param>
+ /// <param name="command">The command that represents the delete operation.</param>
+ /// <param name="commandPosition">The ordinal of this command in the batch.</param>
+ /// <param name="requiresTransaction">Returns whether the SQL appended must be executed in a transaction to work correctly.</param>
+ /// <returns>The <see cref="ResultSetMapping" /> for the command.</returns>
+ protected virtual ResultSetMapping AppendDeleteAndSelectOperation(
+ StringBuilder commandStringBuilder,
+ IReadOnlyModificationCommand command,
+ int commandPosition,
+ out bool requiresTransaction)
+ {
+ var name = command.TableName;
+ var schema = command.Schema;
+ var operations = command.ColumnModifications;
+
+ var conditionOperations = operations.Where(o => o.IsCondition).ToList();
+
+ requiresTransaction = false;
+
+ AppendDeleteCommand(commandStringBuilder, name, schema, Array.Empty<IColumnModification>(), conditionOperations);
+
+ return AppendSelectAffectedCountCommand(commandStringBuilder, name, schema, commandPosition);
+ }
+
+ /// <summary>
+ /// Appends a SQL command for selecting affected data.
+ /// </summary>
+ /// <param name="commandStringBuilder">The builder to which the SQL should be appended.</param>
+ /// <param name="name">The name of the table.</param>
+ /// <param name="schema">The table schema, or <see langword="null" /> to use the default schema.</param>
+ /// <param name="readOperations">The operations representing the data to be read.</param>
+ /// <param name="conditionOperations">The operations used to generate the <c>WHERE</c> clause for the select.</param>
+ /// <param name="commandPosition">The ordinal of the command for which rows affected it being returned.</param>
+ /// <returns>The <see cref="ResultSetMapping" /> for this command.</returns>
+ protected virtual ResultSetMapping AppendSelectAffectedCommand(
+ StringBuilder commandStringBuilder,
+ string name,
+ string? schema,
+ IReadOnlyList<IColumnModification> readOperations,
+ IReadOnlyList<IColumnModification> conditionOperations,
+ int commandPosition)
+ {
+ AppendSelectCommandHeader(commandStringBuilder, readOperations);
+ AppendFromClause(commandStringBuilder, name, schema);
+ AppendWhereAffectedClause(commandStringBuilder, conditionOperations);
+ commandStringBuilder.AppendLine(SqlGenerationHelper.StatementTerminator)
+ .AppendLine();
+
+ return ResultSetMapping.LastInResultSet;
+ }
+
+ /// <summary>
+ /// Appends a SQL fragment for starting a <c>SELECT</c>.
+ /// </summary>
+ /// <param name="commandStringBuilder">The builder to which the SQL should be appended.</param>
+ /// <param name="operations">The operations representing the data to be read.</param>
+ protected virtual void AppendSelectCommandHeader(
+ StringBuilder commandStringBuilder,
+ IReadOnlyList<IColumnModification> operations)
+ => commandStringBuilder
+ .Append("SELECT ")
+ .AppendJoin(
+ operations,
+ SqlGenerationHelper,
+ (sb, o, helper) => helper.DelimitIdentifier(sb, o.ColumnName));
+
+ /// <summary>
+ /// Appends a SQL fragment for starting a <c>FROM</c> clause.
+ /// </summary>
+ /// <param name="commandStringBuilder">The builder to which the SQL should be appended.</param>
+ /// <param name="name">The name of the table.</param>
+ /// <param name="schema">The table schema, or <see langword="null" /> to use the default schema.</param>
+ protected virtual void AppendFromClause(
+ StringBuilder commandStringBuilder,
+ string name,
+ string? schema)
+ {
+ commandStringBuilder
+ .AppendLine()
+ .Append("FROM ");
+ SqlGenerationHelper.DelimitIdentifier(commandStringBuilder, name, schema);
+ }
+
+ /// <summary>
+ /// Appends a <c>WHERE</c> clause involving rows affected.
+ /// </summary>
+ /// <param name="commandStringBuilder">The builder to which the SQL should be appended.</param>
+ /// <param name="operations">The operations from which to build the conditions.</param>
+ protected virtual void AppendWhereAffectedClause(
+ StringBuilder commandStringBuilder,
+ IReadOnlyList<IColumnModification> operations)
+ {
+ commandStringBuilder
+ .AppendLine()
+ .Append("WHERE ");
+
+ AppendRowsAffectedWhereCondition(commandStringBuilder, 1);
+
+ if (operations.Count > 0)
+ {
+ commandStringBuilder
+ .Append(" AND ")
+ .AppendJoin(
+ operations, (sb, v) =>
+ {
+ if (v.IsKey)
+ {
+ if (!v.IsRead)
+ {
+ AppendWhereCondition(sb, v, v.UseOriginalValueParameter);
+ return true;
+ }
+ }
+
+ if (IsIdentityOperation(v))
+ {
+ AppendIdentityWhereCondition(sb, v);
+ return true;
+ }
+
+ return false;
+ }, " AND ");
+ }
+ }
+
+ /// <summary>
+ /// Returns a value indicating whether the given modification represents an auto-incrementing column.
+ /// </summary>
+ /// <param name="modification">The column modification.</param>
+ /// <returns><see langword="true" /> if the given modification represents an auto-incrementing column.</returns>
+ protected virtual bool IsIdentityOperation(IColumnModification modification)
+ => modification.IsKey && modification.IsRead;
+
+ /// <summary>
+ /// Appends a <c>WHERE</c> condition checking rows affected.
+ /// </summary>
+ /// <param name="commandStringBuilder">The builder to which the SQL should be appended.</param>
+ /// <param name="expectedRowsAffected">The expected number of rows affected.</param>
+ protected abstract void AppendRowsAffectedWhereCondition(
+ StringBuilder commandStringBuilder,
+ int expectedRowsAffected);
+
+ /// <summary>
+ /// Appends a <c>WHERE</c> condition for the identity (i.e. key value) of the given column.
+ /// </summary>
+ /// <param name="commandStringBuilder">The builder to which the SQL should be appended.</param>
+ /// <param name="columnModification">The column for which the condition is being generated.</param>
+ protected abstract void AppendIdentityWhereCondition(
+ StringBuilder commandStringBuilder,
+ IColumnModification columnModification);
+
+ /// <summary>
+ /// Appends a SQL command for selecting the number of rows affected.
+ /// </summary>
+ /// <param name="commandStringBuilder">The builder to which the SQL should be appended.</param>
+ /// <param name="name">The name of the table.</param>
+ /// <param name="schema">The table schema, or <see langword="null" /> to use the default schema.</param>
+ /// <param name="commandPosition">The ordinal of the command for which rows affected it being returned.</param>
+ /// <returns>The <see cref="ResultSetMapping" /> for this command.</returns>
+ protected abstract ResultSetMapping AppendSelectAffectedCountCommand(
+ StringBuilder commandStringBuilder,
+ string name,
+ string? schema,
+ int commandPosition);
+}