{"id":332414,"date":"2022-04-26T09:00:09","date_gmt":"2022-04-26T09:00:09","guid":{"rendered":"http:\/\/savepearlharbor.com\/?p=332414"},"modified":"-0001-11-30T00:00:00","modified_gmt":"-0001-11-29T21:00:00","slug":"","status":"publish","type":"post","link":"https:\/\/savepearlharbor.com\/?p=332414","title":{"rendered":"\u0418\u043d\u0432\u0435\u0440\u0441\u0438\u044f \u0437\u0430\u0432\u0438\u0441\u0438\u043c\u043e\u0441\u0442\u0438 \u0438 System.Data.Common.DbDataReader<\/span>"},"content":{"rendered":"
<\/div>\n
\n
\n
\n
\n
<\/figcaption><\/figure>\n

\u0415\u0441\u043b\u0438 \u043c\u044b \u043d\u0435 \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u0443\u0435\u043c EF (\u0442\u0430\u043a\u043e\u0435 \u0441\u043b\u0443\u0447\u0430\u0435\u0442\u0441\u044f), \u0442\u043e \u043d\u0430\u043c \u043d\u0443\u0436\u043d\u043e \u043a\u0430\u043a-\u0442\u043e \u0443\u0441\u0442\u0440\u043e\u0438\u0442\u044c \u0437\u0430\u0433\u0440\u0443\u0437\u043a\u0443 \u043e\u0431\u044a\u0435\u043a\u0442\u043e\u0432 \u0438\u0437 \u0431\u0430\u0437\u044b \u0434\u0430\u043d\u043d\u044b\u0445. \u0412\u0430\u0440\u0438\u0430\u043d\u0442: \u0431\u0435\u0440\u0451\u043c DataSet<\/code>, \u0434\u0435\u043b\u0430\u0435\u043c \u0435\u043c\u0443 SomeDataAdapter.fill(...)<\/code>, \u0430 \u0438\u0437 \u043d\u0435\u0433\u043e \u0431\u0435\u0440\u0451\u043c \u0434\u0430\u043d\u043d\u044b\u0435 \u0434\u043b\u044f \u0441\u0442\u0440\u043e\u0438\u0442\u0435\u043b\u044c\u0441\u0442\u0432\u0430 \u043d\u0443\u0436\u043d\u044b\u0445 \u043e\u0431\u044a\u0435\u043a\u0442\u043e\u0432. \u041f\u0440\u0438 \u044d\u0442\u043e\u043c \u043a\u043b\u0430\u0441\u0441, \u043a\u043e\u0442\u043e\u0440\u044b\u0439 \u0443\u043c\u0435\u0435\u0442 \u0437\u0430\u043f\u043e\u043b\u043d\u044f\u0442\u044c DataSet<\/code>, \u043d\u0435 \u0437\u043d\u0430\u0435\u0442, \u0434\u043b\u044f \u043e\u0431\u044a\u0435\u043a\u0442\u043e\u0432 \u043a\u0430\u043a\u043e\u0433\u043e \u043a\u043b\u0430\u0441\u0441\u0430 \u043e\u043d \u044d\u0442\u043e \u0434\u0435\u043b\u0430\u0435\u0442. \u0410\u0431\u0441\u0442\u0440\u0430\u043a\u0446\u0438\u044f, \u043d\u0438\u0437\u043a\u0430\u044f \u0441\u0432\u044f\u0437\u0430\u043d\u043d\u043e\u0441\u0442\u044c, \u0432\u0441\u0451 \u0445\u043e\u0440\u043e\u0448\u043e. <\/p>\n

\u041e\u0434\u043d\u0430\u043a\u043e, \u043c\u044b \u0436\u0434\u0451\u043c, \u043f\u043e\u043a\u0430 \u0437\u0430\u043f\u043e\u043b\u043d\u0438\u0442\u0441\u044f DataSet<\/code>, \u0442\u043e\u043b\u044c\u043a\u043e \u043f\u043e\u0441\u043b\u0435 \u044d\u0442\u043e\u0433\u043e \u043c\u043e\u0436\u0435\u043c \u043d\u0430\u0447\u0430\u0442\u044c \u043e\u0442\u043f\u0440\u0430\u0432\u043a\u0443 \u043e\u0442\u0432\u0435\u0442\u0430 \u043a\u043b\u0438\u0435\u043d\u0442\u0443.<\/p>\n

\u0420\u0430\u043d\u0435\u0435 \u0432 \u043f\u0443\u0431\u043b\u0438\u043a\u0430\u0446\u0438\u0438 JSON-\u0441\u0435\u0440\u0438\u0430\u043b\u0438\u0437\u0430\u0446\u0438\u044f \u0430\u0441\u0438\u043d\u0445\u0440\u043e\u043d\u043d\u043e\u0433\u043e \u0441\u0442\u0440\u0438\u043c\u0430<\/a> \u043c\u044b \u0440\u0430\u0441\u0441\u043c\u043e\u0442\u0440\u0435\u043b\u0438 \u0441\u043f\u043e\u0441\u043e\u0431, \u043a\u0430\u043a \u043e\u0442\u043f\u0440\u0430\u0432\u043b\u044f\u0442\u044c \u0434\u0430\u043d\u043d\u044b\u0435 \u043f\u043e \u043c\u0435\u0440\u0435 \u043f\u043e\u0441\u0442\u0443\u043f\u043b\u0435\u043d\u0438\u044f \u0441 \u043f\u043e\u043c\u043e\u0449\u044c\u044e SomeDataReader<\/code> (\u043d\u0430\u043f\u0440\u0438\u043c\u0435\u0440, OracleDataReader<\/code>). \u0422\u0430\u043c \u0431\u044b\u043b \u043f\u0440\u0438\u0432\u0435\u0434\u0451\u043d \u043f\u0440\u0438\u043c\u0435\u0440:<\/p>\n

private async IAsyncEnumerable<ICatForListing> GetCatsList() { using OracleConnection conn = GetConnection();      var taskOpenConnection = conn.OpenAsync();      OracleCommand command = conn.CreateCommand();     command.CommandText = \"select STRING_ID, INT_ID, breed, name from T_CATS\";      await taskOpenConnection;      OracleDataReader dataReader = (OracleDataReader) await command.ExecuteReaderAsync();      while (true)     {     Task<bool> canRead = dataReader.ReadAsync();         Cat item = new();         item.Id = new StringIntId();         if(! await canRead)         {         yield break;         }         item.Id.StringId = dataReader[\"STRING_ID\"].ToString()!.Trim();         item.Id.IntId = int.Parse(dataReader[\"INT_ID\"].ToString()!.Trim());         item.Breed = dataReader[\"BREED\"].ToString()!.Trim();         item.Name = dataReader[\"NANE\"].ToString()!.Trim();         yield return item;     } }  ...    public async Task GetCats(HttpContext httpContext) { await httpContext.Response.WriteAsJsonAsync(       GetCatsList(),        new JsonSerializerOptions { PropertyNameCaseInsensitive = false }     ); }<\/code><\/pre>\n
\u0418 \u0442\u0430\u043a \u0434\u0435\u043b\u0430\u0442\u044c, \u043a\u043e\u043d\u0435\u0447\u043d\u043e, \u043d\u0435\u043a\u0440\u0430\u0441\u0438\u0432\u043e. \u041f\u043e\u0442\u043e\u043c\u0443 \u0447\u0442\u043e \u0432 \u0442\u0430\u043a\u043e\u043c \u0441\u043b\u0443\u0447\u0430\u0435 \u0443 \u043d\u0430\u0441 \u043a\u043b\u0430\u0441\u0441, \u043a\u043e\u0442\u043e\u0440\u044b\u0439 \u0443\u043c\u0435\u0435\u0442 \u0440\u0430\u0431\u043e\u0442\u0430\u0442\u044c \u0441 \u0431\u0430\u0437\u043e\u0439 \u0434\u0430\u043d\u043d\u044b\u0445 \u0437\u0430\u0432\u0438\u0441\u0438\u0442 \u043e\u0442 \u0438\u043d\u0442\u0435\u0440\u0444\u0435\u0439\u0441\u0430 ICatForListing<\/code> \u0438 \u043a\u043b\u0430\u0441\u0441\u0430 Cat<\/code>, \u043e\u0442\u043d\u043e\u0441\u044f\u0449\u0438\u0445\u0441\u044f \u043a \u0431\u0438\u0437\u043d\u0435\u0441-\u043c\u043e\u0434\u0435\u043b\u0438.<\/p>\n
\u041c\u043e\u0436\u043d\u043e \u043f\u043e\u043f\u0440\u043e\u0431\u043e\u0432\u0430\u0442\u044c \u043f\u043e\u043b\u0443\u0447\u0438\u0442\u044c \u0430\u0431\u0441\u0442\u0440\u0430\u043a\u0442\u043d\u044b\u0439 DbDataReader \u0438 \u043a\u0440\u0443\u0442\u0438\u0442\u044c \u0435\u0433\u043e \u0443\u0436\u0435 \u043d\u0430 \u0431\u043e\u043b\u0435\u0435 \u0432\u044b\u0441\u043e\u043a\u043e\u043c \u0443\u0440\u043e\u0432\u043d\u0435:<\/p>\n
\/\/ \u043d\u0438\u0437\u043a\u043e\u0443\u0440\u043e\u0432\u043d\u0435\u0432\u044b\u0439 \u043a\u043b\u0430\u0441\u0441, \u0440\u0430\u0431\u043e\u0442\u0430\u044e\u0449\u0438\u0439 \u0441 \u0431\u0430\u0437\u043e\u0439 \u0434\u0430\u043d\u043d\u044b\u0445 public class Database  {   public async Task<DbDataReader> GetCatsDataReader()     {       using OracleConnection conn = GetConnection();     var taskOpenConnection = conn.OpenAsync();     OracleCommand command = conn.CreateCommand();     command.CommandText = \"select STRING_ID, INT_ID, breed, name from T_CATS\";     await taskOpenConnection;     return (DbDataReader) await command.ExecuteReaderAsync();     } }  \/\/ \u043a\u043e\u043d\u0442\u0440\u043e\u043b\u043b\u0435\u0440 ASP.NET public class CatsController  {   private Database _database = new();      private async IAsyncEnumerable<ICatForListing> GetCatsList() {       using DbDataReader dataReader = await _database.GetCatsDataReader();         while (true)         {             Task<bool> canRead = dataReader.ReadAsync();             Cat item = new();             item.Id = new StringIntId();             if(! await canRead)             {                 yield break;             }             item.Id.StringId = dataReader[\"STRING_ID\"].ToString()!.Trim();             item.Id.IntId = int.Parse(dataReader[\"INT_ID\"].ToString()!.Trim());             item.Breed = dataReader[\"BREED\"].ToString()!.Trim();             item.Name = dataReader[\"NANE\"].ToString()!.Trim();             yield return item;         }     }      ...        public async Task GetCats(HttpContext httpContext)     {         await httpContext.Response.WriteAsJsonAsync(           GetCatsList(),            new JsonSerializerOptions { PropertyNameCaseInsensitive = false }         );     } }  <\/code><\/pre>\n
\u041e\u043a\u0430\u0437\u044b\u0432\u0430\u0435\u0442\u0441\u044f, \u044d\u0442\u043e \u043d\u0435 \u0440\u0430\u0431\u043e\u0442\u0430\u0435\u0442:<\/p>\n
System.InvalidOperationException : Invalid attempt to call Read when reader is closed.<\/code><\/pre>\n
\u042d\u0442\u043e \u0438\u0437-\u0437\u0430 using<\/code><\/p>\n
using OracleConnection conn = GetConnection();<\/code><\/pre>\n
\u041f\u0440\u0438 \u0432\u044b\u0445\u043e\u0434\u0435 \u0438\u0437 \u043c\u0435\u0442\u043e\u0434\u0430 \u0441\u043e\u0435\u0434\u0438\u043d\u0435\u043d\u0438\u0435 \u0437\u0430\u043a\u0440\u044b\u0432\u0430\u0435\u0442\u0441\u044f, \u0442\u0430\u043a \u043a\u0430\u043a \u0432\u044b\u0437\u044b\u0432\u0430\u0435\u0442\u0441\u044f Dispose()<\/code>. \u041f\u0440\u0438\u0434\u0451\u0442\u0441\u044f using<\/code> \u0443\u0431\u0440\u0430\u0442\u044c:<\/p>\n
\/\/ \u043d\u0438\u0437\u043a\u043e\u0443\u0440\u043e\u0432\u043d\u0435\u0432\u044b\u0439 \u043a\u043b\u0430\u0441\u0441, \u0440\u0430\u0431\u043e\u0442\u0430\u044e\u0449\u0438\u0439 \u0441 \u0431\u0430\u0437\u043e\u0439 \u0434\u0430\u043d\u043d\u044b\u0445 public class Database  {   public async Task<DbDataReader> GetCatsDataReader()     {       \/*using*\/ OracleConnection conn = GetConnection();     var taskOpenConnection = conn.OpenAsync();     OracleCommand command = conn.CreateCommand();     command.CommandText = \"select STRING_ID, INT_ID, breed, name from T_CATS\";     await taskOpenConnection;     return (DbDataReader) await command.ExecuteReaderAsync();     } } <\/code><\/pre>\n
\u0422\u0435\u043f\u0435\u0440\u044c \u043a\u043e\u0442\u0438\u043a\u0438 \u0432\u044b\u0432\u043e\u0434\u044f\u0442\u0441\u044f, \u043d\u043e \u0443 \u043d\u0430\u0441 \u0432\u0438\u0441\u0438\u0442 \u043d\u0435\u0437\u0430\u043a\u0440\u044b\u0442\u043e\u0435 \u0441\u043e\u0435\u0434\u0438\u043d\u0435\u043d\u0438\u0435, \u0447\u0442\u043e \u0442\u0430\u043a\u0436\u0435 \u043d\u0435\u043a\u0440\u0430\u0441\u0438\u0432\u043e.<\/p>\n
\u0418 \u0442\u0443\u0442 \u043d\u0430\u0441 \u043f\u043e\u0441\u0435\u0449\u0430\u0435\u0442 \u0438\u0434\u0435\u044f: \u0430 \u0434\u0430\u0432\u0430\u0439\u0442\u0435 \u0432\u043e\u0437\u0432\u0440\u0430\u0449\u0430\u0442\u044c \u0442\u043e\u0442 \u0436\u0435 DbDataReader<\/code>, \u043d\u043e \u043d\u0435 \u0446\u0435\u043b\u0438\u043a\u043e\u043c, \u0430 \u043d\u0430 \u043a\u0430\u0436\u0434\u043e\u0439 \u0441\u0442\u0440\u043e\u043a\u0435 \u0434\u0430\u043d\u043d\u044b\u0445 \u0447\u0435\u0440\u0435\u0437 IAsyncEnumerator<DbDataReader><\/code>! \u042d\u0442\u043e \u043e\u0437\u043d\u0430\u0447\u0430\u0435\u0442, \u0447\u0442\u043e \u043c\u044b \u043e\u0441\u0442\u0430\u043d\u0435\u043c\u0441\u044f \u0432\u043d\u0443\u0442\u0440\u0438 \u043c\u0435\u0442\u043e\u0434\u0430 GetCatsDataReader() \u0434\u043e \u043a\u043e\u043d\u0446\u0430 \u0434\u0430\u043d\u043d\u044b\u0445, \u0441\u043e\u0435\u0434\u0438\u043d\u0435\u043d\u0438\u0435 \u0437\u0430\u043a\u0440\u043e\u0435\u0442\u0441\u044f \u043f\u0440\u0430\u0432\u0438\u043b\u044c\u043d\u043e \u0438 \u043d\u0430\u0448\u0430 \u043f\u0435\u0440\u0432\u043e\u043d\u0430\u0447\u0430\u043b\u044c\u043d\u0430\u044f \u0446\u0435\u043b\u044c \u0442\u0430\u043a\u0436\u0435 \u0431\u0443\u0434\u0435\u0442 \u0434\u043e\u0441\u0442\u0438\u0433\u043d\u0443\u0442\u0430. \u0418\u0442\u0430\u043a:<\/p>\n
\/\/ \u043d\u0438\u0437\u043a\u043e\u0443\u0440\u043e\u0432\u043d\u0435\u0432\u044b\u0439 \u043a\u043b\u0430\u0441\u0441, \u0440\u0430\u0431\u043e\u0442\u0430\u044e\u0449\u0438\u0439 \u0441 \u0431\u0430\u0437\u043e\u0439 \u0434\u0430\u043d\u043d\u044b\u0445 public class Database  {   public async IAsyncEnumerable<DbDataReader> GetCatsDataReader()     {       using OracleConnection conn = GetConnection();     var taskOpenConnection = conn.OpenAsync();     OracleCommand command = conn.CreateCommand();     command.CommandText = \"select STRING_ID, INT_ID, breed, name from T_CATS\";     await taskOpenConnection;       using OracleDataReader dr =  (OracleDataReader) await cmd.ExecuteReaderAsync();          while (await dr.ReadAsync())         {             yield return (DbDataReader)dr;         }     } }  \/\/ \u043a\u043e\u043d\u0442\u0440\u043e\u043b\u043b\u0435\u0440 ASP.NET public class CatsController  {   private Database _database = new();      private async IAsyncEnumerable<ICatForListing> GetCatsList() {         foreach (DbDataReader dataReader in GetCatsDataReader())         {             Cat item = new();             item.Id = new StringIntId();             item.Id.StringId = dataReader[\"STRING_ID\"].ToString()!.Trim();             item.Id.IntId = int.Parse(dataReader[\"INT_ID\"].ToString()!.Trim());             item.Breed = dataReader[\"BREED\"].ToString()!.Trim();             item.Name = dataReader[\"NANE\"].ToString()!.Trim();             yield return item;         }     }      ...        public async Task GetCats(HttpContext httpContext)     {         await httpContext.Response.WriteAsJsonAsync(           GetCatsList(),            new JsonSerializerOptions { PropertyNameCaseInsensitive = false }         );     } }  <\/code><\/pre>\n
\u041f\u0440\u043e\u0432\u0435\u0440\u0435\u043d\u043e, \u0440\u0430\u0431\u043e\u0442\u0430\u0435\u0442!<\/p>\n<\/p>\n<\/div>\n<\/div>\n<\/div>\n
<\/div>\n<\/div>\n
  
 \u0441\u0441\u044b\u043b\u043a\u0430 \u043d\u0430 \u043e\u0440\u0438\u0433\u0438\u043d\u0430\u043b \u0441\u0442\u0430\u0442\u044c\u0438  https:\/\/habr.com\/ru\/post\/662976\/<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"
<\/div>\n
\n
\n
\n
\n
<\/figcaption><\/figure>\n
\u0415\u0441\u043b\u0438 \u043c\u044b \u043d\u0435 \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u0443\u0435\u043c EF (\u0442\u0430\u043a\u043e\u0435 \u0441\u043b\u0443\u0447\u0430\u0435\u0442\u0441\u044f), \u0442\u043e \u043d\u0430\u043c \u043d\u0443\u0436\u043d\u043e \u043a\u0430\u043a-\u0442\u043e \u0443\u0441\u0442\u0440\u043e\u0438\u0442\u044c \u0437\u0430\u0433\u0440\u0443\u0437\u043a\u0443 \u043e\u0431\u044a\u0435\u043a\u0442\u043e\u0432 \u0438\u0437 \u0431\u0430\u0437\u044b \u0434\u0430\u043d\u043d\u044b\u0445. \u0412\u0430\u0440\u0438\u0430\u043d\u0442: \u0431\u0435\u0440\u0451\u043c DataSet<\/code>, \u0434\u0435\u043b\u0430\u0435\u043c \u0435\u043c\u0443 SomeDataAdapter.fill(...)<\/code>, \u0430 \u0438\u0437 \u043d\u0435\u0433\u043e \u0431\u0435\u0440\u0451\u043c \u0434\u0430\u043d\u043d\u044b\u0435 \u0434\u043b\u044f \u0441\u0442\u0440\u043e\u0438\u0442\u0435\u043b\u044c\u0441\u0442\u0432\u0430 \u043d\u0443\u0436\u043d\u044b\u0445 \u043e\u0431\u044a\u0435\u043a\u0442\u043e\u0432. \u041f\u0440\u0438 \u044d\u0442\u043e\u043c \u043a\u043b\u0430\u0441\u0441, \u043a\u043e\u0442\u043e\u0440\u044b\u0439 \u0443\u043c\u0435\u0435\u0442 \u0437\u0430\u043f\u043e\u043b\u043d\u044f\u0442\u044c DataSet<\/code>, \u043d\u0435 \u0437\u043d\u0430\u0435\u0442, \u0434\u043b\u044f \u043e\u0431\u044a\u0435\u043a\u0442\u043e\u0432 \u043a\u0430\u043a\u043e\u0433\u043e \u043a\u043b\u0430\u0441\u0441\u0430 \u043e\u043d \u044d\u0442\u043e \u0434\u0435\u043b\u0430\u0435\u0442. \u0410\u0431\u0441\u0442\u0440\u0430\u043a\u0446\u0438\u044f, \u043d\u0438\u0437\u043a\u0430\u044f \u0441\u0432\u044f\u0437\u0430\u043d\u043d\u043e\u0441\u0442\u044c, \u0432\u0441\u0451 \u0445\u043e\u0440\u043e\u0448\u043e. <\/p>\n
\u041e\u0434\u043d\u0430\u043a\u043e, \u043c\u044b \u0436\u0434\u0451\u043c, \u043f\u043e\u043a\u0430 \u0437\u0430\u043f\u043e\u043b\u043d\u0438\u0442\u0441\u044f DataSet<\/code>, \u0442\u043e\u043b\u044c\u043a\u043e \u043f\u043e\u0441\u043b\u0435 \u044d\u0442\u043e\u0433\u043e \u043c\u043e\u0436\u0435\u043c \u043d\u0430\u0447\u0430\u0442\u044c \u043e\u0442\u043f\u0440\u0430\u0432\u043a\u0443 \u043e\u0442\u0432\u0435\u0442\u0430 \u043a\u043b\u0438\u0435\u043d\u0442\u0443.<\/p>\n
\u0420\u0430\u043d\u0435\u0435 \u0432 \u043f\u0443\u0431\u043b\u0438\u043a\u0430\u0446\u0438\u0438  JSON-\u0441\u0435\u0440\u0438\u0430\u043b\u0438\u0437\u0430\u0446\u0438\u044f \u0430\u0441\u0438\u043d\u0445\u0440\u043e\u043d\u043d\u043e\u0433\u043e \u0441\u0442\u0440\u0438\u043c\u0430<\/a> \u043c\u044b \u0440\u0430\u0441\u0441\u043c\u043e\u0442\u0440\u0435\u043b\u0438 \u0441\u043f\u043e\u0441\u043e\u0431, \u043a\u0430\u043a \u043e\u0442\u043f\u0440\u0430\u0432\u043b\u044f\u0442\u044c \u0434\u0430\u043d\u043d\u044b\u0435 \u043f\u043e \u043c\u0435\u0440\u0435 \u043f\u043e\u0441\u0442\u0443\u043f\u043b\u0435\u043d\u0438\u044f \u0441 \u043f\u043e\u043c\u043e\u0449\u044c\u044e SomeDataReader<\/code> (\u043d\u0430\u043f\u0440\u0438\u043c\u0435\u0440, OracleDataReader<\/code>). \u0422\u0430\u043c \u0431\u044b\u043b \u043f\u0440\u0438\u0432\u0435\u0434\u0451\u043d \u043f\u0440\u0438\u043c\u0435\u0440:<\/p>\n
private async IAsyncEnumerable<ICatForListing> GetCatsList() { using OracleConnection conn = GetConnection();      var taskOpenConnection = conn.OpenAsync();      OracleCommand command = conn.CreateCommand();     command.CommandText = \"select STRING_ID, INT_ID, breed, name from T_CATS\";      await taskOpenConnection;      OracleDataReader dataReader = (OracleDataReader) await command.ExecuteReaderAsync();      while (true)     {     Task<bool> canRead = dataReader.ReadAsync();         Cat item = new();         item.Id = new StringIntId();         if(! await canRead)         {         yield break;         }         item.Id.StringId = dataReader[\"STRING_ID\"].ToString()!.Trim();         item.Id.IntId = int.Parse(dataReader[\"INT_ID\"].ToString()!.Trim());         item.Breed = dataReader[\"BREED\"].ToString()!.Trim();         item.Name = dataReader[\"NANE\"].ToString()!.Trim();         yield return item;     } }  ...    public async Task GetCats(HttpContext httpContext) { await httpContext.Response.WriteAsJsonAsync(       GetCatsList(),        new JsonSerializerOptions { PropertyNameCaseInsensitive = false }     ); }<\/code><\/pre>\n
\u0418 \u0442\u0430\u043a \u0434\u0435\u043b\u0430\u0442\u044c, \u043a\u043e\u043d\u0435\u0447\u043d\u043e, \u043d\u0435\u043a\u0440\u0430\u0441\u0438\u0432\u043e. \u041f\u043e\u0442\u043e\u043c\u0443 \u0447\u0442\u043e \u0432 \u0442\u0430\u043a\u043e\u043c \u0441\u043b\u0443\u0447\u0430\u0435 \u0443 \u043d\u0430\u0441 \u043a\u043b\u0430\u0441\u0441, \u043a\u043e\u0442\u043e\u0440\u044b\u0439 \u0443\u043c\u0435\u0435\u0442 \u0440\u0430\u0431\u043e\u0442\u0430\u0442\u044c \u0441 \u0431\u0430\u0437\u043e\u0439 \u0434\u0430\u043d\u043d\u044b\u0445 \u0437\u0430\u0432\u0438\u0441\u0438\u0442 \u043e\u0442 \u0438\u043d\u0442\u0435\u0440\u0444\u0435\u0439\u0441\u0430 ICatForListing<\/code> \u0438 \u043a\u043b\u0430\u0441\u0441\u0430 Cat<\/code>, \u043e\u0442\u043d\u043e\u0441\u044f\u0449\u0438\u0445\u0441\u044f \u043a \u0431\u0438\u0437\u043d\u0435\u0441-\u043c\u043e\u0434\u0435\u043b\u0438.<\/p>\n
\u041c\u043e\u0436\u043d\u043e \u043f\u043e\u043f\u0440\u043e\u0431\u043e\u0432\u0430\u0442\u044c \u043f\u043e\u043b\u0443\u0447\u0438\u0442\u044c \u0430\u0431\u0441\u0442\u0440\u0430\u043a\u0442\u043d\u044b\u0439 DbDataReader \u0438 \u043a\u0440\u0443\u0442\u0438\u0442\u044c \u0435\u0433\u043e \u0443\u0436\u0435 \u043d\u0430 \u0431\u043e\u043b\u0435\u0435 \u0432\u044b\u0441\u043e\u043a\u043e\u043c \u0443\u0440\u043e\u0432\u043d\u0435:<\/p>\n
\/\/ \u043d\u0438\u0437\u043a\u043e\u0443\u0440\u043e\u0432\u043d\u0435\u0432\u044b\u0439 \u043a\u043b\u0430\u0441\u0441, \u0440\u0430\u0431\u043e\u0442\u0430\u044e\u0449\u0438\u0439 \u0441 \u0431\u0430\u0437\u043e\u0439 \u0434\u0430\u043d\u043d\u044b\u0445 public class Database  {   public async Task<DbDataReader> GetCatsDataReader()     {       using OracleConnection conn = GetConnection();     var taskOpenConnection = conn.OpenAsync();     OracleCommand command = conn.CreateCommand();     command.CommandText = \"select STRING_ID, INT_ID, breed, name from T_CATS\";     await taskOpenConnection;     return (DbDataReader) await command.ExecuteReaderAsync();     } }  \/\/ \u043a\u043e\u043d\u0442\u0440\u043e\u043b\u043b\u0435\u0440 ASP.NET public class CatsController  {   private Database _database = new();      private async IAsyncEnumerable<ICatForListing> GetCatsList() {       using DbDataReader dataReader = await _database.GetCatsDataReader();         while (true)         {             Task<bool> canRead = dataReader.ReadAsync();             Cat item = new();             item.Id = new StringIntId();             if(! await canRead)             {                 yield break;             }             item.Id.StringId = dataReader[\"STRING_ID\"].ToString()!.Trim();             item.Id.IntId = int.Parse(dataReader[\"INT_ID\"].ToString()!.Trim());             item.Breed = dataReader[\"BREED\"].ToString()!.Trim();             item.Name = dataReader[\"NANE\"].ToString()!.Trim();             yield return item;         }     }      ...        public async Task GetCats(HttpContext httpContext)     {         await httpContext.Response.WriteAsJsonAsync(           GetCatsList(),            new JsonSerializerOptions { PropertyNameCaseInsensitive = false }         );     } }  <\/code><\/pre>\n
\u041e\u043a\u0430\u0437\u044b\u0432\u0430\u0435\u0442\u0441\u044f, \u044d\u0442\u043e \u043d\u0435 \u0440\u0430\u0431\u043e\u0442\u0430\u0435\u0442:<\/p>\n
System.InvalidOperationException : Invalid attempt to call Read when reader is closed.<\/code><\/pre>\n
\u042d\u0442\u043e \u0438\u0437-\u0437\u0430 using<\/code><\/p>\n
using OracleConnection conn = GetConnection();<\/code><\/pre>\n
\u041f\u0440\u0438 \u0432\u044b\u0445\u043e\u0434\u0435 \u0438\u0437 \u043c\u0435\u0442\u043e\u0434\u0430 \u0441\u043e\u0435\u0434\u0438\u043d\u0435\u043d\u0438\u0435 \u0437\u0430\u043a\u0440\u044b\u0432\u0430\u0435\u0442\u0441\u044f, \u0442\u0430\u043a \u043a\u0430\u043a \u0432\u044b\u0437\u044b\u0432\u0430\u0435\u0442\u0441\u044f Dispose()<\/code>. \u041f\u0440\u0438\u0434\u0451\u0442\u0441\u044f using<\/code> \u0443\u0431\u0440\u0430\u0442\u044c:<\/p>\n
\/\/ \u043d\u0438\u0437\u043a\u043e\u0443\u0440\u043e\u0432\u043d\u0435\u0432\u044b\u0439 \u043a\u043b\u0430\u0441\u0441, \u0440\u0430\u0431\u043e\u0442\u0430\u044e\u0449\u0438\u0439 \u0441 \u0431\u0430\u0437\u043e\u0439 \u0434\u0430\u043d\u043d\u044b\u0445 public class Database  {   public async Task<DbDataReader> GetCatsDataReader()     {       \/*using*\/ OracleConnection conn = GetConnection();     var taskOpenConnection = conn.OpenAsync();     OracleCommand command = conn.CreateCommand();     command.CommandText = \"select STRING_ID, INT_ID, breed, name from T_CATS\";     await taskOpenConnection;     return (DbDataReader) await command.ExecuteReaderAsync();     } } <\/code><\/pre>\n
\u0422\u0435\u043f\u0435\u0440\u044c \u043a\u043e\u0442\u0438\u043a\u0438 \u0432\u044b\u0432\u043e\u0434\u044f\u0442\u0441\u044f, \u043d\u043e \u0443 \u043d\u0430\u0441 \u0432\u0438\u0441\u0438\u0442 \u043d\u0435\u0437\u0430\u043a\u0440\u044b\u0442\u043e\u0435 \u0441\u043e\u0435\u0434\u0438\u043d\u0435\u043d\u0438\u0435, \u0447\u0442\u043e \u0442\u0430\u043a\u0436\u0435 \u043d\u0435\u043a\u0440\u0430\u0441\u0438\u0432\u043e.<\/p>\n
\u0418 \u0442\u0443\u0442 \u043d\u0430\u0441 \u043f\u043e\u0441\u0435\u0449\u0430\u0435\u0442 \u0438\u0434\u0435\u044f: \u0430 \u0434\u0430\u0432\u0430\u0439\u0442\u0435 \u0432\u043e\u0437\u0432\u0440\u0430\u0449\u0430\u0442\u044c \u0442\u043e\u0442 \u0436\u0435 DbDataReader<\/code>, \u043d\u043e \u043d\u0435 \u0446\u0435\u043b\u0438\u043a\u043e\u043c, \u0430 \u043d\u0430 \u043a\u0430\u0436\u0434\u043e\u0439 \u0441\u0442\u0440\u043e\u043a\u0435 \u0434\u0430\u043d\u043d\u044b\u0445 \u0447\u0435\u0440\u0435\u0437 IAsyncEnumerator<DbDataReader><\/code>! \u042d\u0442\u043e \u043e\u0437\u043d\u0430\u0447\u0430\u0435\u0442, \u0447\u0442\u043e \u043c\u044b \u043e\u0441\u0442\u0430\u043d\u0435\u043c\u0441\u044f \u0432\u043d\u0443\u0442\u0440\u0438 \u043c\u0435\u0442\u043e\u0434\u0430 GetCatsDataReader() \u0434\u043e \u043a\u043e\u043d\u0446\u0430 \u0434\u0430\u043d\u043d\u044b\u0445, \u0441\u043e\u0435\u0434\u0438\u043d\u0435\u043d\u0438\u0435 \u0437\u0430\u043a\u0440\u043e\u0435\u0442\u0441\u044f \u043f\u0440\u0430\u0432\u0438\u043b\u044c\u043d\u043e \u0438 \u043d\u0430\u0448\u0430 \u043f\u0435\u0440\u0432\u043e\u043d\u0430\u0447\u0430\u043b\u044c\u043d\u0430\u044f \u0446\u0435\u043b\u044c \u0442\u0430\u043a\u0436\u0435 \u0431\u0443\u0434\u0435\u0442 \u0434\u043e\u0441\u0442\u0438\u0433\u043d\u0443\u0442\u0430. \u0418\u0442\u0430\u043a:<\/p>\n
\/\/ \u043d\u0438\u0437\u043a\u043e\u0443\u0440\u043e\u0432\u043d\u0435\u0432\u044b\u0439 \u043a\u043b\u0430\u0441\u0441, \u0440\u0430\u0431\u043e\u0442\u0430\u044e\u0449\u0438\u0439 \u0441 \u0431\u0430\u0437\u043e\u0439 \u0434\u0430\u043d\u043d\u044b\u0445 public class Database  {   public async IAsyncEnumerable<DbDataReader> GetCatsDataReader()     {       using OracleConnection conn = GetConnection();     var taskOpenConnection = conn.OpenAsync();     OracleCommand command = conn.CreateCommand();     command.CommandText = \"select STRING_ID, INT_ID, breed, name from T_CATS\";     await taskOpenConnection;       using OracleDataReader dr =  (OracleDataReader) await cmd.ExecuteReaderAsync();          while (await dr.ReadAsync())         {             yield return (DbDataReader)dr;         }     } }  \/\/ \u043a\u043e\u043d\u0442\u0440\u043e\u043b\u043b\u0435\u0440 ASP.NET public class CatsController  {   private Database _database = new();      private async IAsyncEnumerable<ICatForListing> GetCatsList() {         foreach (DbDataReader dataReader in GetCatsDataReader())         {             Cat item = new();             item.Id = new StringIntId();             item.Id.StringId = dataReader[\"STRING_ID\"].ToString()!.Trim();             item.Id.IntId = int.Parse(dataReader[\"INT_ID\"].ToString()!.Trim());             item.Breed = dataReader[\"BREED\"].ToString()!.Trim();             item.Name = dataReader[\"NANE\"].ToString()!.Trim();             yield return item;         }     }      ...        public async Task GetCats(HttpContext httpContext)     {         await httpContext.Response.WriteAsJsonAsync(           GetCatsList(),            new JsonSerializerOptions { PropertyNameCaseInsensitive = false }         );     } }  <\/code><\/pre>\n
\u041f\u0440\u043e\u0432\u0435\u0440\u0435\u043d\u043e, \u0440\u0430\u0431\u043e\u0442\u0430\u0435\u0442!<\/p>\n<\/p>\n<\/div>\n<\/div>\n<\/div>\n
<\/div>\n<\/div>\n
  
 \u0441\u0441\u044b\u043b\u043a\u0430 \u043d\u0430 \u043e\u0440\u0438\u0433\u0438\u043d\u0430\u043b \u0441\u0442\u0430\u0442\u044c\u0438  https:\/\/habr.com\/ru\/post\/662976\/<\/a>
<\/br><\/br><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[],"tags":[],"class_list":["post-332414","post","type-post","status-publish","format-standard","hentry"],"_links":{"self":[{"href":"https:\/\/savepearlharbor.com\/index.php?rest_route=\/wp\/v2\/posts\/332414","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/savepearlharbor.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/savepearlharbor.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/savepearlharbor.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/savepearlharbor.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=332414"}],"version-history":[{"count":0,"href":"https:\/\/savepearlharbor.com\/index.php?rest_route=\/wp\/v2\/posts\/332414\/revisions"}],"wp:attachment":[{"href":"https:\/\/savepearlharbor.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=332414"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/savepearlharbor.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=332414"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/savepearlharbor.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=332414"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}