Roslyn+T4+EnvDTE專案完全自動化(3) ——生成c++代碼

C++語法復雜，寫一個示例通過T4可生成c++代碼

需求：資料庫，生成c++增，刪，改，查代碼

1. 資料生成c++類，包含所有欄位
2. 自動識別資料的主鍵Key
3. 查詢生成賦值類欄位，型別轉換
4. 通過類自動生成sql的where條件
5. 類改變一些欄位值，自動生成update sql
6. 生成所有欄位列印代碼

class Actor_Entry;      //資料庫物體類
class Actor_UpdateEntry;//更新物體類
class Actor             //物體增，刪，改，查類
{
public:
    bool Select(MYSQL* connect, const std::string& sql, std::vector<Actor_Entry>& out);
    bool SelectAll(MYSQL* connect, std::vector<Actor_Entry>& v);
    bool Update(MYSQL* connect, const Actor_UpdateEntry& set, const Actor_UpdateEntry& where, const std::string& whereSql);
    bool Update(MYSQL* connect, const std::string& whereSql);
    bool Insert(MYSQL* connect, Actor_UpdateEntry& v);
    bool Delete(MYSQL* connect, const Actor_UpdateEntry& v);
};
class Actor_Entry
{
public:
    std::string ToString();
    static Actor_Entry& New();//方便拷貝代碼
    short int GetKey() const;
    // 資料欄位，及型別映射
    // 主鍵（自動識別主鍵）
    short int Actor_Id;
    std::string First_Name;
    std::string Last_Name;
    std::string Last_Update;
};
//欄位發生改變，自動生成sql
class Actor_UpdateEntry : public Actor_Entry
{
public:
    Actor_UpdateEntry(); 
    static Actor_UpdateEntry& New();//方便拷貝代碼
    bool IsModified() const;
    void ResetModified();
    void Set_Actor_Id(const short int value);
    bool Actor_Id_Modified;

    void Set_First_Name(const std::string& value);
    bool First_Name_Modified;

    void Set_Last_Name(const std::string& value);
    bool Last_Name_Modified;

    void Set_Last_Update(const std::string& value);
    bool Last_Update_Modified;
};

一個資料庫，不到10s生成7000+行代碼

 實作方式：

讀取表結構：

        public static IEnumerable<TABLE_SCHEMA_> GetTableSchemaEnumerable(MySqlConnectionStringBuilder builder)
        {
            using (var conn = GetConnection(builder))
            {
                var sql =
                    $"SELECT DISTINCT t.`TABLE_COMMENT`, c.* FROM information_schema.`COLUMNS` as c INNER join INFORMATION_SCHEMA.`TABLES` t on c.`TABLE_NAME`= t.`TABLE_NAME`  where c.TABLE_SCHEMA = '{builder.Database}';";

                using (var cmd = conn.CreateCommand())
                {
                    cmd.CommandText = sql;

                    using (var reader = cmd.ExecuteReader())
                    {
                        while (reader.Read())
                        {
                            var obj = new TABLE_SCHEMA_();
                            obj.TABLE_COMMENT = reader[nameof(obj.TABLE_COMMENT)].DbCast<string>();
                            obj.TABLE_NAME = reader[nameof(obj.TABLE_NAME)].DbCast<string>();
                            obj.TABLE_CATALOG = reader[nameof(obj.TABLE_CATALOG)];
                            obj.TABLE_SCHEMA = reader[nameof(obj.TABLE_SCHEMA)];
                            obj.TABLE_NAME = reader[nameof(obj.TABLE_NAME)].DbCast<string>();
                            obj.COLUMN_NAME = reader[nameof(obj.COLUMN_NAME)].DbCast<string>();
                            obj.ORDINAL_POSITION = reader[nameof(obj.ORDINAL_POSITION)].DbCast<uint>();
                            obj.COLUMN_DEFAULT = reader[nameof(obj.COLUMN_DEFAULT)];
                            {
                                var v = reader[nameof(obj.IS_NULLABLE)];
                                obj.IS_NULLABLE = "Yes".EqualsByIgnoreCaseEx(v.DbCast<string>());
                            }
                            obj.DATA_TYPE = reader[nameof(obj.DATA_TYPE)].DbCast<string>();
                            obj.CHARACTER_MAXIMUM_LENGTH = reader[nameof(obj.CHARACTER_MAXIMUM_LENGTH)].DbCast<long?>();
                            obj.CHARACTER_OCTET_LENGTH = reader[nameof(obj.CHARACTER_OCTET_LENGTH)].DbCast<long?>();
                            obj.NUMERIC_PRECISION = reader[nameof(obj.NUMERIC_PRECISION)];
                            obj.NUMERIC_SCALE = reader[nameof(obj.NUMERIC_SCALE)];
                            obj.DATETIME_PRECISION = reader[nameof(obj.DATETIME_PRECISION)];
                            obj.CHARACTER_SET_NAME = reader[nameof(obj.CHARACTER_SET_NAME)].DbCast<string>();
                            obj.COLLATION_NAME = reader[nameof(obj.COLLATION_NAME)].DbCast<string>();
                            obj.COLUMN_TYPE = reader[nameof(obj.COLUMN_TYPE)].DbCast<string>();
                            obj.COLUMN_KEY = reader[nameof(obj.COLUMN_KEY)].DbCast<string>();
                            obj.EXTRA = reader[nameof(obj.EXTRA)];
                            obj.PRIVILEGES = reader[nameof(obj.PRIVILEGES)];
                            obj.COLUMN_COMMENT = reader[nameof(obj.COLUMN_COMMENT)].DbCast<string>();
                            obj.GENERATION_EXPRESSION = reader[nameof(obj.GENERATION_EXPRESSION)];
                            obj.SRS_ID = reader[nameof(obj.SRS_ID)];
                            yield return obj;
                        }
                    }
                }
            }
        }

用t4生成c++代碼：

bool <#= className #>::Insert(MYSQL* connect, <#= tab.ClassName_UpdateEntry #>& v)
{
    if(!v.IsModified())
    {
        return false;
    }
	std::string f;
	std::string values;
<#+
    var isOneKey = tab.Keys.Length == 1;//判斷是不是單主鍵
    foreach (var field in tab.FieldsSupported)
    {
        var type = field.Type;
        var name = field.Name;
#>
    if (v.<#=field.NameModify#>)
    {
	    f += " `<#=field.ColumnName#>`,";
	    values += std::format(" '{}',", v.<#=field.Name#>);
    }
<#+
	}
#>
<#+if(isOneKey){//自增主鍵，自動寫入insert的生成的key#>
    {
	    std::string sql = std::format("insert into `<#=tab.TabName#>` ({}) values({});", f.substr(0, f.length() - 1), values.substr(0, values.length() - 1));
        int query = mysql_query(connect, sql.c_str());
        // if (!query) return false;
    }
    {
        std::string sql = "SELECT LAST_INSERT_ID() as id;";
        int query = mysql_query(connect, sql.c_str());
        // if (!query) return false;
    }
	
    auto res = mysql_use_result(connect);
    if(res == nullptr) return false;

    MYSQL_ROW row;
    while ((row = mysql_fetch_row(res)) != nullptr)
    {
        v.<#=tab.Keys[0].Name#> = Columns::GetInt(row, 0);
        break;
    }
    mysql_free_result(res);
<#+}else{#>
	std::string sql = std::format("insert into `<#=tab.TabName#>` ({}) values({});", f.substr(0, f.length() - 1), values.substr(0, values.length() - 1));
	int query = mysql_query(connect, sql.c_str());
	if (!query) return false;
<#+}#>
	return true;
}

（c++代碼多年沒寫，有可能有誤，只是為了測驗T4）

Roslyn+T4+EnvDTE ，基本上可以從一種資料源生成，另一種任意格式文本格式

視頻演示

 代碼

提取碼：ynpb

標籤：C#

上一篇：SVG交集設定顏色

下一篇：（五）React Ant Design Pro + .Net5 WebApi：后端環境搭建-Autofac注入+ 泛型倉儲