DbModelGenerator 0.5.5

DbModelGenerator

A .NET Roslyn incremental source generator that generates POCO record classes from SQL migration scripts.

It is compatible with PostgreSQL syntax and pairs well with Dapper, DapperExtensions, and DbUp for a true database-first workflow.

How it works

1. You write SQL migration scripts (CREATE TABLE, ALTER TABLE, …) organised in sub-directories under Scripts/.
2. DbModelGenerator reads those scripts at compile time (as a Roslyn analyzer) and generates one C# record per table.
3. Generated classes are injected directly into your compilation — no files to commit, no pre-build step to configure.

Installation

Add the package to your .csproj:

<ItemGroup>
    <PackageReference Include="DbModelGenerator" Version="0.5.2"/>
</ItemGroup>

Then expose your SQL migration scripts as AdditionalFiles so the analyzer can read them:

<ItemGroup>
    <AdditionalFiles Include="Scripts\**\*"/>
</ItemGroup>

That's all. The generator runs automatically on every build.

Scripts directory structure

MyProject/
└── Scripts/
    ├── db.json          ← optional configuration file
    ├── Global/          ← one namespace per sub-directory
    │   └── 01_create_tables.sql
    └── Tenant/
        ├── 01_create_tables.sql
        └── 02_alter_table.sql

• Each sub-directory maps to a generated C# namespace: {ProjectName}.Generated.Db.{SubDirectoryName}.
• Scripts inside a sub-directory are applied in alphabetical order (standard DbUp convention).
• The generator supports CREATE TABLE, ALTER TABLE (add/drop/rename column, add/drop constraint), and DROP TABLE.

Example

Given Scripts/Tenant/01_create_tables.sql:

CREATE TABLE user_profile
(
    id        SERIAL       NOT NULL,
    email     VARCHAR(255) NOT NULL,
    firstName VARCHAR(255) NOT NULL,
    disabled  BOOLEAN      NOT NULL DEFAULT '0',
    PRIMARY KEY (id)
);

The generator produces (in MyProject.Generated.Db.Tenant):

public sealed record UserProfile(
    int Id,
    string Email,
    string FirstName,
    bool Disabled
);

Configuration — Scripts/db.json

Place an optional db.json file directly inside the Scripts/ directory to customise code generation:

{
  "interfaces": [
    "My.Namespace.IEntity",
    "My.Namespace.IDbEntity(created_by)"
  ],
  "primaryKeyAttribute": "My.Namespace.PrimaryKey",
  "autoIncrementAttribute": "My.Namespace.AutoIncrement",
  "suffix": "Db",
  "ignores": ["audit_log", "migration_history"]
}

Interface matching

An interface is applied to a class only when all the listed properties exist on the table.

"interfaces": [
    "My.App.IEntity",
    "My.App.IDbEntity(created_by)"
]

• My.App.IEntity — applied to every table that has an id column (default property when none specified).
• My.App.IDbEntity(created_by) — applied only to tables that have a created_by column.

Generic type parameters — suffix a property name with ! to use its C# type as a generic type argument:

"My.App.IEntity(id!)"

This generates IEntity<int> when id is SERIAL, IEntity<string> when id is TEXT, etc.

Custom scripts directory

By default the generator looks for scripts in {ProjectDir}/Scripts. Override this with the ScriptsDir MSBuild property:

<PropertyGroup>
    <ScriptsDir>Migrations</ScriptsDir>
</PropertyGroup>

SQL type mapping (PostgreSQL)

Nullable columns (without NOT NULL) produce nullable C# types (int?, string?, …). SERIAL / SMALLSERIAL / BIGSERIAL columns are always nullable (int?) since their value is assigned by the database on insert.

Complete example

See the Example.Service project for a working end-to-end setup.