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c# - 将实体框架 T4 模板与系统版本化的临时表一起使用

问题描述

为了解决我的错误（如下所示），我想知道如何编辑我的 Entity Framework T4 模板，以便将“<strong>HasDatabaseGeneratedOption(DatabaseGeneratedOption.Computed)”添加到我的临时表的 GENERATED ALWAYS AS ROW START/END 列在自动生成的类的 POCO 配置部分中，如下所示：

Property(x => x.ValidFrom).HasColumnName(@"valid_from").HasColumnType("datetime2").IsRequired().HasDatabaseGeneratedOption(DatabaseGeneratedOption.Computed);
Property(x => x.ValidTo).HasColumnName(@"valid_to").HasColumnType("datetime2").IsRequired().HasDatabaseGeneratedOption(DatabaseGeneratedOption.Computed);

我可以手动添加它（这解决了我的错误），但是当我保存 T4 模板时它当然会被覆盖。

尝试插入记录时出错：“无法在表 'my_table' 中的 GENERATED ALWAYS 列中插入显式值。将 INSERT 与列列表一起使用以排除 GENERATED ALWAYS 列，或将 DEFAULT 插入 GENERATED ALWAYS 列。”

我看到了这篇文章，但没有帮助（也许它只在使用 edmx 文件时有效，或者我不明白解决方案）：Entity Framework not working with temporal table

我的临时表示例：

CREATE TABLE [dbo].[my_table](
    [id] [int] IDENTITY(1,1) NOT NULL,
    [user_id] [int] NOT NULL,
    [valid_from] [datetime2](7) GENERATED ALWAYS AS ROW START NOT NULL,
    [valid_to] [datetime2](7) GENERATED ALWAYS AS ROW END NOT NULL,
 CONSTRAINT [PK_my_table] PRIMARY KEY CLUSTERED 
(
    [id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY],
    PERIOD FOR SYSTEM_TIME ([valid_from], [valid_to])
) ON [PRIMARY]
WITH
(
SYSTEM_VERSIONING = ON ( HISTORY_TABLE = [dbo].[my_table_history] )
)
GO
ALTER TABLE [dbo].[my_table] ADD  CONSTRAINT [DF_my_table_SysStart]  DEFAULT (sysutcdatetime()) FOR [valid_from]
GO
ALTER TABLE [dbo].[my_table] ADD  CONSTRAINT [DF_my_table_SysEnd]  DEFAULT (CONVERT([datetime2](7),'9999-12-31 23:59:59')) FOR [valid_to]
GO

插入记录的示例代码：

var recordToCreate = new MyTable()
{
    UserId = info.UserId,
    ValidFrom = info.ValidFrom,
    ValidTo = info.ValidTo,
};
_context.MyTables.Add(recordToCreate);
_context.SaveChanges();

标签： c#sql-serverentity-frameworkt4temporal-tables

解决方案

我想到了。我不得不编辑 EF.Reverse.POCO.Core.ttinclude 文件，将“IsGeneratedAlwaysType”添加到许多类、方法和 SQL 查询中。我基本上在我发现“IsForeignKey”的所有地方都添加了它。我已将我添加到每个部分的内容片段粘贴在下面。

public class Column
{
    public bool IsGeneratedAlwaysType;

    private void SetupConfig()
    {
        else if (IsGeneratedAlwaysType)
        {
            if(Settings.UseDataAnnotations)
                DataAnnotations.Add("DatabaseGenerated(DatabaseGeneratedOption.Computed)");
            else
                databaseGeneratedOption = string.Format(".HasDatabaseGeneratedOption({0}DatabaseGeneratedOption.Computed)", schemaReference);
        }

    private static Column CreateColumn(IDataRecord rdr, Regex rxClean, Table table, Regex columnFilterExclude)
    { 
        var col = new Column
        {
            IsGeneratedAlwaysType = rdr["IsGeneratedAlwaysType"].ToString().Trim().ToLower() == "true",

private class SqlServerSchemaReader : SchemaReader
{
    private const string TableSQL = @"
    CAST(CASE WHEN COLUMNPROPERTY(OBJECT_ID(QUOTENAME(c.TABLE_SCHEMA) + '.' + QUOTENAME(c.TABLE_NAME)), c.COLUMN_NAME, 'GeneratedAlwaysType') > 0 THEN 1
         ELSE 0
       END AS BIT) AS IsGeneratedAlwaysType
    FROM    #Columns c

private const string SynonymTableSQLSetup = @"
        CAST(CASE WHEN COLUMNPROPERTY(OBJECT_ID(QUOTENAME(sc.NAME) + '.' + QUOTENAME(o.NAME)), c.NAME, 'GeneratedAlwaysType') > 0 THEN 1
                  ELSE 0
             END AS BIT) AS IsGeneratedAlwaysType
        INTO    #SynonymDetails
        FROM    sys.synonyms sn

INSERT INTO #SynonymDetails (SchemaName, TableName, TableType, Ordinal, ColumnName, IsNullable, TypeName, [MaxLength], [Precision],
                            [Default], DateTimePrecision, Scale, IsIdentity, IsStoreGenerated, PrimaryKey, PrimaryKeyOrdinal, IsForeignKey, IsGeneratedAlwaysType)

CAST(CASE WHEN COLUMNPROPERTY(st.base_object_id, c.NAME, ''GeneratedAlwaysType'') > 0 THEN 1
                ELSE 0
            END AS BIT) AS IsGeneratedAlwaysType
FROM    #SynonymTargets st
    INNER JOIN sys.columns c

        private const string SynonymTableSQL = @"
SELECT SchemaName, TableName, TableType, Ordinal, ColumnName, IsNullable, TypeName, [MaxLength], [Precision],
    [Default], DateTimePrecision, Scale, IsIdentity, IsStoreGenerated, PrimaryKey, PrimaryKeyOrdinal, IsForeignKey, IsGeneratedAlwaysType FROM #SynonymDetails";

        private const string TableSQLCE = @"
0 as IsGeneratedAlwaysType
FROM    INFORMATION_SCHEMA.COLUMNS c

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