Linq-收到错误“无法将类型为“ System.String”的对象转换为类型为“ System.Byte []”。”

Question

This is the first time I have tried to use LINQ. I have a database table that consists of two string columns, one bit column, and an id column defined as an int. The table holds configuration data so there is only a single row.

Database definition...

CREATE TABLE [dbo].[Configuration](
[Id] [int] IDENTITY(1,1) NOT NULL,
[LegalRepository] [nvarchar](100) NOT NULL,
[TitleRepository] [nvarchar](100) NOT NULL,
[AlwaysOpenOnDesktop] [bit] NOT NULL
) ON [PRIMARY]

The query looks like this...

Configuration config = fileSearchDB.Configurations.Single(c => c.Id == configId);

The Configuration class is...

[global::System.Data.Linq.Mapping.TableAttribute(Name="dbo.Configuration")]
public partial class Configuration
{

    private int _Id;

    private System.Data.Linq.Binary _LegalRepository;

    private System.Data.Linq.Binary _TitleRepository;

    private bool _AlwaysOpenOnDesktop;

    public Configuration()
    {
    }

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_Id", AutoSync=AutoSync.Always, DbType="Int NOT NULL IDENTITY", IsDbGenerated=true)]
    public int Id
    {
        get
        {
            return this._Id;
        }
        set
        {
            if ((this._Id != value))
            {
                this._Id = value;
            }
        }
    }

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_LegalRepository", DbType="VarBinary(MAX) NOT NULL", CanBeNull=false, UpdateCheck=UpdateCheck.Never)]
    public System.Data.Linq.Binary LegalRepository
    {
        get
        {
            return this._LegalRepository;
        }
        set
        {
            if ((this._LegalRepository != value))
            {
                this._LegalRepository = value;
            }
        }
    }

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_TitleRepository", DbType="VarBinary(MAX) NOT NULL", CanBeNull=false, UpdateCheck=UpdateCheck.Never)]
    public System.Data.Linq.Binary TitleRepository
    {
        get
        {
            return this._TitleRepository;
        }
        set
        {
            if ((this._TitleRepository != value))
            {
                this._TitleRepository = value;
            }
        }
    }

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_AlwaysOpenOnDesktop", DbType="Bit NOT NULL")]
    public bool AlwaysOpenOnDesktop
    {
        get
        {
            return this._AlwaysOpenOnDesktop;
        }
        set
        {
            if ((this._AlwaysOpenOnDesktop != value))
            {
                this._AlwaysOpenOnDesktop = value;
            }
        }
    }
}

The int field configId = 1, which is the id of the only row in the table.

Why am I receiving this error?

Unable to cast object of type 'System.String' to type 'System.Byte[]'

Thanks, Gary

UPDATED: I have added the definition of the Configuration class and that the configId variable is an int

Answer 1

After looking at the definition of the Configuration class I see that the repository fields are defined as binary. They should be strings. I deleted the configuration table and readded it and the columns were now defined as strings.

Answer 2

Your definition of Configuration declares LegalRepository and TitleRepository as immutable binary fields, when in the database, they're simple strings. Either the DB declaration of the fields must change to varbinary , or the object fields should become ordinary string properties.