Dapper：字符串未被识别为有效的 DateTime

Question

我正在使用 Dapper 访问 sqlite 数据库并获取 'String was not recognized as a valid DateTime.'。感谢任何帮助。

// Create table schema
CREATE TABLE "mytable" ( "field1"   TEXT, "field2"  TEXT, "field3"  TEXT, 
                         "field4"   TEXT, "field5"  TEXT, 
                         "field6"   bit, 
                         "field7"   TEXT, "field8"  TEXT, "field9"  TEXT,
                         "field10"  TEXT, 
                         "field11"  DateTime )

查询代码：

var result= sqliteConnection.Query<TestItem>("Select * from mytable");

插入数据的查询：

INSERT INTO "main"."mytable" ("field1", "field2", "field3", "field4", "field5", "field6", "field7", "field8", "field9", "field10", "field11") VALUES ('750eb223-2993-4d85-9d4f-3e8689e9baa7', 'some value', '', 'some value', 'some value', '1', '84', 'ae35e1e1-dd4c-4e49-a76c-d577f417bf9a', 'some value', 'HOME.aspx', 
                             '2020/01/20 17:38');
INSERT INTO "main"."mytable" ("field1", "field2", "field3", "field4", "field5", "field6", "field7", "field8", "field9", "field10", "field11") VALUES ('750eb223-2993-4d85-9d4f-3e8689e9baa7', 'some value', 'asdf', 'some value', 'some value', '1', '32', 'a1cd1b8f-95f6-4b03-8d54-f904c21749ac', 'HOME.aspx', 'HOME.aspx', 
                              '2020/01/20 17:38');
INSERT INTO "main"."mytable" ("field1", "field2", "field3", "field4", "field5", "field6", "field7", "field8", "field9", "field10", "field11") VALUES ('750eb223-2993-4d85-9d4f-3e8689e9baa7', 'some value', 'some value', 'some value', 'some value', '1', '99', 'b9e63bfd-c73e-4e9a-b3e7-30ae49d8a002', 'CALLSS.aspx', 'CALLSS.aspx', 
                              '2020/01/20 17:38');

错误信息：

Error parsing column 10 (field11=HOME.aspx - String)

内部异常消息：

String was not recognized as a valid DateTime.

堆栈跟踪：

at Dapper.SqlMapper.ThrowDataException(Exception ex, Int32 index, IDataReader reader, Object value) in C:\projects\dapper\Dapper\SqlMapper.cs:line 3609
   at Dapper.SqlMapper.<QueryImpl>d__138`1.MoveNext() in C:\projects\dapper\Dapper\SqlMapper.cs:line 1100
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at Dapper.SqlMapper.Query[T](IDbConnection cnn, String sql, Object param, IDbTransaction transaction, Boolean buffered, Nullable`1 commandTimeout, Nullable`1 commandType) in C:\projects\dapper\Dapper\SqlMapper.cs:line 723
   at Tzunami.LinkResolver.DatabaseMigration.Models.DBMigrator.<MigrateDeploymentListItemAsync>d__5.MoveNext() in C:\Users\surendra\source\repos\Tzunami.LinkResolver.MigrationTool\Tzunami.LinkResolver.DatabaseMigration\Models\DBMigrator.cs:line 77

映射项class:

public class TestItem
{
  public string Field1 { get; set; }
  public string Field2 { get; set; }
  public string Field3 { get; set; }
  public string Field4 { get; set; }
  public string Field5 { get; set; }
  public string Field6 { get; set; }
  public string Field7 { get; set; }
  public string Field8 { get; set; }
  public string Field9 { get; set; }
  public string Field10 { get; set; }
  public string Field11 { get; set; }
}

数据库架构和条目可以从以下从 DB SQLite 浏览器中获取的示例中看到

Answer 1

首先：请记住，如 Sqlite 文档中所述，没有 Datatypes，因为 DateTime 它以某种方式存储为文本或一些数字，因此最好将日期保存为纯文本数据库创建。此处的文档：https://www.sqlite.org/datatype3.html

其次：预计日期时间采用 ISO8601 格式，即“YYYY-MM-DD HH:MM:SS.SSS”格式，但作为 table 上的数据，它是“YYYY-MM-DD HH:MM" 它不能被解析为 DateTime.

解决方法：

由于您无法更改数据库架构和数据，因此 connection.ExecuteReader 在这些情况下工作得很好，因此使用 connection.ExecuteReader 并使用 reader.GetString() 方法将列值作为字符串获取。

Answer 2

尝试使用此格式作为字符串。

'2007-01-01 10:00:00'

即yyyy-MM-dd HH:mm:ss

Answer 3

我从未使用过 SQLite，但根据 document，SQLite 没有可存储的数据类型 DateTime。

2.2. Date and Time Datatype
SQLite does not have a storage class set aside for storing dates and/or times. Instead, the built-in Date And Time Functions of SQLite are capable of storing dates and times as TEXT, REAL, or INTEGER values:

TEXT as ISO8601 strings ("YYYY-MM-DD HH:MM:SS.SSS").

REAL as Julian day numbers, the number of days since noon in Greenwich on November 24, 4714 B.C. according to the proleptic Gregorian calendar.

INTEGER as Unix Time, the number of seconds since 1970-01-01 00:00:00 UTC.

Applications can chose to store dates and times in any of these formats and freely convert between formats using the built-in date and time functions.

考虑到以上，您在以下代码中的日期格式：

INSERT INTO "main"."mytable" (..., "field11") VALUES (..., '2020/01/20 17:38');

应该是

YYYY-MM-DD HH:MM:SS.SSS

这样，您不需要更改数据库架构；只需更改您的代码。

Dapper：字符串未被识别为有效的 DateTime

Dapper: String was not recognized as a valid DateTime

c#

sqlite

dapper