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T4 Models

T4 models are used to generate POCO's C# code using your database structure.


Firstly you should install one of tools packages into your project:

Install-Package linq2db.XXX

Where XXX is one of supported databases, for example:

Install-Package linq2db.SqlServer

This also will install needed linq2db packages:

  • linq2db.t4models
  • linq2db

But not data provider packages (install them only if needed to compile your project, T4 models ships it's own data provider assemblies).

.Net Core specific

Because of .Net Core projects do not support NuGet content files all stuff is not copied into project's folder, so to run T4 templates you'll need:

  • open $(SolutionDir).tools\linq2db.t4models in Explorer
  • copy to your project's folder or subfolder, then you should use it instead of


After package installing you will see new LinqToDB.Templates folder in your project, this folder contains all needed T4 stuff to generate your model. Also would be created new folder in tour solution: $(SolutionDir).tools\linq2db.t4models, it is used to store and link assemblies, needed for generation (linq2db.dll and data provider assemblies).

To create a data model template take a look at one of the file in your LinqToDB.Templates project folder. Copy this file to needed project location and rename it, like

There are few main steps in this file:

  1. Configuring generation process (read below)
  2. Loading metadata - this is a call to LoadMatadata() function - it connects to your database and fetches all needed metadata (table structure, views, and so on)
  3. Customizing generation process (read below)
  4. Calling GenerateModel() - this will run model generation

Configuring generation process

Use the following initialization before you call the LoadMetadata() method.

NamespaceName                 = "DataModels";       // Namespace of the generated classes.

DataContextName               = null;               // DataContext class name. If null - database name + "DB".
BaseDataContextClass          = null;               // Base DataContext class name. If null - LinqToDB.Data.DataConnection.
GenerateConstructors          = true;               // Enforce generating DataContext constructors.
DefaultConfiguration          = null;               // Defines default configuration for default DataContext constructor.

BaseEntityClass               = null;               // Base Entity class name. If null - none.
DatabaseName                  = null;               // Table database name - [Table(Database="DatabaseName")].
GenerateDatabaseName          = false;              // Always generate table database name, even though DatabaseName is null.
IncludeDefaultSchema          = true;               // Default schema name is generated - [Table(Database="Northwind", Schema="dbo", Name="Customers")]

OneToManyAssociationType      = "IEnumerable<{0}>"; // One To Many association type (for members only). Change it to "List<{0}>" if needed.
GenerateAssociations          = true;               // Enforce generating associations as type members.
GenerateBackReferences        = true;               // Enforce generating backreference associations (affects both members and extensions).
GenerateAssociationExtensions = false;              // Enforce generating associations as extension methods. NB: this option does not affect GenerateAssociations. This will require linq2db 1.9.0 and above

ReplaceSimilarTables          = true;               // Replaces stored procedure result class names with similar to existing table class names.
GenerateFindExtensions        = true;               // Generates find extension methods based on PKs information.
IsCompactColumns              = true;               // If true, column compact view.

PluralizeClassNames                 = false;   // If true, pluralizes table class names.
SingularizeClassNames               = true;    // If true, singularizes table class names.
PluralizeDataContextPropertyNames   = true;    // If true, pluralizes DataContext property names.
SingularizeDataContextPropertyNames = false;   // If true, singularizes DataContex pProperty names.

GenerateDataTypes                   = false;   // If true, generates the DataType/Length/Precision/Scale properties of the Column attribute (unless overriden by the properties below).
GenerateDataTypeProperty            = null;    // If true, generates the DataType property of the Column attribute. If false, excludes generation on the DataType property even if GenerateDataTypes == true.
GenerateLengthProperty              = null;    // If true, generates the Length property of the Column attribute. If false, excludes generation on the Length property even if GenerateDataTypes == true.
GeneratePrecisionProperty           = null;    // If true, generates the Precision property of the Column attribute. If false, excludes generation on the Precision property even if GenerateDataTypes == true.
GenerateScaleProperty               = null;    // If true, generates the Scale property of the Column attribute. If false, excludes generation on the Scale property even if GenerateDataTypes == true.
GenerateDbTypes                     = false;   // If true, generates the DbType property of the Column attribute.

GenerateObsoleteAttributeForAliases = false;   // If true, generates [Obsolete] attribute for aliases.
IsCompactColumnAliases              = true;    // If true, column alias compact view.

NormalizeNames                      = false;   // convert some_name to SomeName for types and members

GetSchemaOptions.GetTables     = true; // Enables generation of table mappings
GetSchemaOptions.GetProcedures = true; // Enables generation of procedures and functions mappings

GetSchemaOptions.ExcludedSchemas = new[] { "TestUser", "SYSSTAT" }; // Defines excluded schemas.
GetSchemaOptions.IncludedSchemas = new[] { "TestUser", "SYS" };     // Defines only included schemas.

GetSchemaOptions.ExcludedCatalogs = new[] { "TestUser", "SYSSTAT" }; // Defines excluded catalogs.
GetSchemaOptions.IncludedCatalogs = new[] { "TestUser", "SYS" };     // Defines only included catalogs.

GetSchemaOptions.GetAssociationMemberName = key => "Association_" + key.MemberName;     // Defines custom naming logic for generated associations.

GetSchemaOptions.LoadProcedure = p => true; // Procedure/function load filter. By default all procedures/functions loaded

// check GetSchemaOptions class for more options

Func<string, bool, string> ToValidName         = ToValidNameDefault;          // Defines function to convert names to valid (My_Table to MyTable) 
Func<string, bool, string> ConvertToCompilable = ConvertToCompilableDefault;  // Converts name to c# compatible. By default removes uncompatible symbols and converts result with ToValidName

Func<ForeignKey, string> GetAssociationExtensionSinglularName = GetAssociationExtensionSinglularNameDefault; // Gets singular method extension method name for association 
Func<ForeignKey, string> GetAssociationExtensionPluralName    = GetAssociationExtensionPluralNameDefault;    // Gets plural method extension method name for association 

Provider specific configurations

SQL Server

bool GenerateSqlServerFreeText = true; // Defines wheather to generate extensions for Free Text search, or not


bool GenerateCaseSensitiveNames = false; // Defines whether to generate case sensitive or insensitive names 


bool GenerateSybaseSystemTables = false; // Defines whether to generate Sybase sysobjects tables or not

Customizing generation process

Use the following code to modify your model before you call the GenerateModel() method.

GetTable("Person").TypeName  = "MyName";                                            // Replaces table name.
GetTable("Person").BaseClass = "PersonBase, IId";                                   // Set base class & interface for type, null to reset 

GetColumn("Person", "PersonID")    .MemberName   = "ID";                            // Replaces column PersonID of Person table with ID.
GetColumn("Person", "PasswordHash").SkipOnUpdate = true;                            // Set [Column(SkipOnUpdate=true)], same for other column options
GetColumn("Person", "Gender")      .Type         = "global::Model.Gender";          // Change column type

GetFK("Orders", "FK_Orders_Customers").MemberName      = "Customers";               // Replaces association name.
GetFK("Orders", "FK_Orders_Customers").AssociationType = AssociationType.OneToMany; // Changes association type.

SetTable(string tableName,
	string TypeName = null,
	string DataContextPropertyName = null)

	.Column(string columnName, string MemberName = null, string Type = null, bool? IsNullable = null)
	.FK    (string fkName,     string MemberName = null, AssociationType? AssociationType = null)

Model.Usings.Add("MyNamespace"); // Adds using of namespace.

// Replaces all the columns where name is 'TableName' + 'ID' with 'ID'.
foreach (var t in Tables.Values)
	foreach (var c in t.Columns.Values)
		if (c.IsPrimaryKey && c.MemberName == t.TypeName + "ID")
			c.MemberName = "ID";

Useful members and data structures

Dictionary<string,Table>     Tables     = new Dictionary<string,Table>    ();
Dictionary<string,Procedure> Procedures = new Dictionary<string,Procedure>();

Table      GetTable     (string name);
Procedure  GetProcedure (string name);
Column     GetColumn    (string tableName, string columnName);
ForeignKey GetFK        (string tableName, string fkName);
ForeignKey GetForeignKey(string tableName, string fkName);

public class Table
	public string Schema;
	public string TableName;
	public string DataContextPropertyName;
	public bool   IsView;
	public string Description;
	public string AliasPropertyName;
	public string AliasTypeName;
	public string TypeName;

	public Dictionary<string,Column>     Columns;
	public Dictionary<string,ForeignKey> ForeignKeys;

public partial class Column : Property
	public string    ColumnName; // Column name in database
	public bool      IsNullable;
	public bool      IsIdentity;
	public string    ColumnType; // Type of the column in database
	public DbType    DbType;
	public string    Description;
	public bool      IsPrimaryKey;
	public int       PrimaryKeyOrder;
	public bool      SkipOnUpdate;
	public bool      SkipOnInsert;
	public bool      IsDuplicateOrEmpty;
	public string    AliasName;
	public string    MemberName;

public enum AssociationType

public partial class ForeignKey : Property
	public string           KeyName;
	public Table            OtherTable;
	public List<Column>     ThisColumns;
	public List<Column>     OtherColumns;
	public bool             CanBeNull;
	public ForeignKey       BackReference;
	public string           MemberName;
	public AssociationType  AssociationType;

public partial class Procedure : Method
	public string          Schema;
	public string          ProcedureName;
	public bool            IsFunction;
	public bool            IsTableFunction;
	public bool            IsDefaultSchema;

	public Table           ResultTable;
	public Exception       ResultException;
	public List<Table>     SimilarTables;
	public List<Parameter> ProcParameters;

public class Parameter
	public string   SchemaName;
	public string   SchemaType;
	public bool     IsIn;
	public bool     IsOut;
	public bool     IsResult;
	public int?     Size;
	public string   ParameterName;
	public string   ParameterType;
	public Type     SystemType;
	public string   DataType;