Add columns in migrations

Arc’s column helpers let a migration select the corresponding database type for PostgreSQL, SQL Server, or SQLite. The mappings below show where those providers differ.

These extension methods are similar to the Common Column Types used when creating tables, but are specifically designed for AddColumn operations in migrations.

Available AddColumn Extension Methods

The following methods extend MigrationBuilder. Import Cratis.Arc.EntityFrameworkCore; AddJsonColumn<T> additionally requires Cratis.Arc.EntityFrameworkCore.Json. Examples are migration fragments using your application’s context and schema; they do not run independently.

Extension Method	Description	Supported Types	Parameters
`AddStringColumn()`	Adds a string column with appropriate database-specific type (VARCHAR/NVARCHAR/TEXT)	string	`name`, `table`, `maxLength` (int?, optional), `nullable` (bool, default: true), `defaultValue` (string?, optional), `schema` (string?, optional)
`AddNumberColumn<T>()`	Adds a numeric column with appropriate database-specific type for any numeric type	char, byte, sbyte, short, ushort, int, uint, long, ulong, float, double, decimal	`name`, `table`, `nullable` (bool, default: true), `defaultValue` (object?, optional), `schema` (string?, optional)
`AddBoolColumn()`	Adds a boolean column with appropriate database-specific type (BOOLEAN/BIT/INTEGER)	bool	`name`, `table`, `nullable` (bool, default: true), `defaultValue` (bool, default: false), `schema` (string?, optional)
`AddAutoIncrementColumn()`	Adds an auto-incrementing integer column with appropriate database-specific annotations	int	`name`, `table`, `schema` (string?, optional)
`AddGuidColumn()`	Adds a GUID/UUID column with appropriate database-specific type (UUID/UNIQUEIDENTIFIER/BLOB)	Guid	`name`, `table`, `nullable` (bool, default: true), `schema` (string?, optional)
`AddDateTimeOffsetColumn()`	Adds a DateTimeOffset column with appropriate database-specific type (TIMESTAMPTZ/DATETIMEOFFSET/TEXT)	DateTimeOffset	`name`, `table`, `nullable` (bool, default: true), `schema` (string?, optional)
`AddPointColumn()`	Declares a spatial/text column; not a model converter	Point	`name`, `table`, `nullable: true`, `schema`
`AddLineStringColumn()`	Declares a spatial/text column; not a model converter	LineString	`name`, `table`, `nullable: true`, `schema`
`AddPolygonColumn()`	Declares a spatial/text column; not a model converter	Polygon	`name`, `table`, `nullable: true`, `schema`
`AddJsonColumn<T>()`	Declares a non-nullable JSON column	JSON property type	`name`, `table`, `schema`

Geometry helpers select geometry(Point, 4326), geometry(LineString, 4326), or geometry(Polygon, 4326) on PostgreSQL; geography on SQL Server; and TEXT on SQLite. They do not install spatial provider mappings or make plain JSON string converters compatible with native spatial columns. See the storage-path matrix.

On PostgreSQL, AddJsonColumn<T>() selects jsonb and adds a JSON CHECK constraint and a GIN index using jsonb_path_ops. The column, constraint, and index are emitted as separate, terminated commands. The index uses a ::jsonb expression, so an explicitly overridden text or json store type also works. Generated constraint and index names are quoted; names exceeding PostgreSQL’s 63-byte identifier limit are shortened with a stable hash suffix.

Adding non-nullable columns to populated tables may require a default or a staged backfill. Verify the generated SQL, model compatibility, permissions, and provider restrictions before applying any migration.

Database-Specific Type Mappings

The extension methods automatically select the appropriate SQL type based on the database provider. See Common Column Types for detailed type mappings for each database.

Usage Examples

Adding String Columns

[DbContext(typeof(MyDbContext))]
[Migration($"MyContext_{nameof(v1_1_0)}")]
public class v1_1_0 : Migration
{
    protected override void Up(MigrationBuilder migrationBuilder)
    {
        // Add string column with length limit
        migrationBuilder.AddStringColumn(
            name: "Email",
            table: "Users",
            maxLength: 255,
            nullable: false);

        // Add unlimited text column with default value
        migrationBuilder.AddStringColumn(
            name: "Description",
            table: "Products",
            defaultValue: "No description provided");
    }

    protected override void Down(MigrationBuilder migrationBuilder)
    {
        migrationBuilder.DropColumn(name: "Email", table: "Users");
        migrationBuilder.DropColumn(name: "Description", table: "Products");
    }
}

Adding Numeric Columns

protected override void Up(MigrationBuilder migrationBuilder)
{
    // Add integer column
    migrationBuilder.AddNumberColumn<int>(
        name: "ViewCount",
        table: "Articles",
        defaultValue: 0,
        nullable: false);

    // Add decimal column for currency
    migrationBuilder.AddNumberColumn<decimal>(
        name: "Price",
        table: "Products",
        nullable: true);

    // Add double column for ratings
    migrationBuilder.AddNumberColumn<double>(
        name: "Rating",
        table: "Reviews",
        defaultValue: 0.0,
        nullable: false);
}

Adding Boolean Columns

protected override void Up(MigrationBuilder migrationBuilder)
{
    migrationBuilder.AddBoolColumn(
        name: "IsActive",
        table: "Users",
        defaultValue: true,
        nullable: false);

    migrationBuilder.AddBoolColumn(
        name: "IsDeleted",
        table: "Orders",
        defaultValue: false);
}

Adding GUID Columns

protected override void Up(MigrationBuilder migrationBuilder)
{
    migrationBuilder.AddGuidColumn(
        name: "ExternalId",
        table: "Users",
        nullable: false);

    migrationBuilder.AddGuidColumn(
        name: "CorrelationId",
        table: "Events",
        nullable: true);
}

Adding DateTime Columns

protected override void Up(MigrationBuilder migrationBuilder)
{
    migrationBuilder.AddDateTimeOffsetColumn(
        name: "LastLoginAt",
        table: "Users",
        nullable: true);

    migrationBuilder.AddDateTimeOffsetColumn(
        name: "CreatedAt",
        table: "Orders",
        nullable: false);
}

Adding Auto-Increment Columns

protected override void Up(MigrationBuilder migrationBuilder)
{
    // Add auto-increment column (useful for adding sequence numbers to existing tables)
    migrationBuilder.AddAutoIncrementColumn(
        name: "SequenceNumber",
        table: "AuditLog");
}

Using Schemas

For databases that support schemas (PostgreSQL, SQL Server), you can specify the schema:

protected override void Up(MigrationBuilder migrationBuilder)
{
    migrationBuilder.AddStringColumn(
        name: "Department",
        table: "Employees",
        schema: "hr",
        maxLength: 100,
        nullable: false);
}

Benefits

Using these extension methods provides several advantages:

Database Portability: Write migrations once and support multiple database providers
Type Safety: Strongly typed methods reduce errors
Consistency: Ensures consistent type mapping across your application
Simplified Syntax: Less boilerplate code compared to manually specifying types
Maintainability: Centralized type mapping logic makes updates easier