ntext in ServiceStack.OrmLite

问题

how can i have nText datatype in ServiceStack.OrmLite Code first ?

public class Email
{
    [AutoIncrement]
    public long ID { get; set; }


    public DateTime Date { get; set; }

    public string From { get; set; }

    public string Subject { get; set; } 

    nText =>
    public string Body { get; set; } 

}

if i use string datatype , ormlite generate nVarchar(8000) in database

i need more than 8000 character for data

回答1:

You need to convert your Body type to byte[] from string for ServiceStack.OrmLite to use the varchar(max) column type. Something like the below:

public byte[] Body { get; set; }

The reason for this lies within the ServiceStack.OrmLite code.

In the file ServiceStack.OrmLite/OrmLiteDialectProviderBase.cs, under the method InitColumnTypeMap() is:

DbTypeMap.Set<byte[]>(DbType.Binary, BlobColumnDefinition);

In the file ServiceStack.OrmLite.SqlServer/SqlServerOrmLiteDialectProvider.cs, under the method SqlServerOrmLiteDialectProvider() is:

base.BlobColumnDefinition = "VARBINARY(MAX)";

From this code, you can see that an internal mapping is taking place from the C# type to the internal ServiceStack.OrmLite type and then back out to the SqlServer type.

This question explains how to convert back and forth between strings and byte arrays, How do I get a consistent byte representation of strings in C# without manually specifying an encoding?.

回答2:

Assuming you really want NTEXT. If you want nvarchar(max) or varchar(max) see https://stackoverflow.com/a/25729568/37055

Decorate your domain model with System.ComponentModel.DataAnnotations.StringLengthAttribute

such as

[StringLengthAttribute(8001)]
public string Markdown { get;set; }

[StringLength(Int32.MaxValue)]
public string Markdown { get;set; }

using any length greater than 8000 to exceed to maximum length of Sql Server varchar/nvarchar column types.

Use a custom dialect provider the understands the NTEXT declaration.

public class NTextSqlProvider : SqlServerOrmLiteDialectProvider
{
  public new static readonly NTextSqlProvider Instance = new NTextSqlProvider();

  public override string GetColumnDefinition(string fieldName, Type fieldType, 
            bool isPrimaryKey, bool autoIncrement, bool isNullable, 
            int? fieldLength, int? scale, string defaultValue)
  {
     var fieldDefinition = base.GetColumnDefinition(fieldName, fieldType,
                                    isPrimaryKey, autoIncrement, isNullable, 
                                    fieldLength, scale, defaultValue);

     if (fieldType == typeof (string) && fieldLength > 8000)
     {
       var orig = string.Format(StringLengthColumnDefinitionFormat, fieldLength);

       fieldDefinition = fieldDefinition.Replace(orig, "NTEXT");
     }

     return fieldDefinition;
  }
}

Use the provider when you construct the database factory

var dbFactory = new OrmLiteConnectionFactory(conStr, NTextSqlProvider.Instance);

来源：https://stackoverflow.com/questions/11281726/ntext-in-servicestack-ormlite

标签

sql-server

code-first

servicestack

ormlite-servicestack