> Shout out to @YassinEldeeb for building the awesome bootstrap project create-prisma-generator. Without it, this would have taken significantly more time to get into a deployable state.

prisma-generator-entityframework

Prisma. It's great, but if you're from the .NET clan, you're left standing out in the rain. Maybe there's still a way? What if the prisma.schema file could generate an EntityFramework client?

Usage

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In your schema.prisma file, add a new generator called entityframework (or whatever you like):

``prisma
// + generator entityframework {
// + provider = "npx prisma-generator-entityframework"
// + output = "../types"
// + namespace = "MyNamespace"
// + clientClassName = "DataDbContext"
// + }

datasource db {
provider = "postgresql"
url = "postgresql://user:password@my_postgres_host.com:5432/initial_db"
}

// Here's some example model code
model User {
id Int @id @default(autoincrement())
email String @unique
name String?
posts Post[]
comment Comment[]

@@map("system_user")
}

...

`

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Run prisma generate or npx prisma generate on your schema.

The prisma-generator-entityframework declaration you added will generate a C# EntityFramework client interface based on the models you have declared in your schema file.

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In your C# project(s), you now should be able to do things like:

`C#
using MyNamespace;

...

var context = new DataDbContext(); // if you're new to EntityFramework, it will come preconfigured with smarts to call your db connection, no batteries required!
context.User.Add(new User {
email = "john.doe@gmail.com",
name = "John Doe",
});
context.SaveChanges();

Console.WriteLine(context.User.Where(user => user.name == "John Doe").First().email);
// john.doe@gmail.com
`

Configuration

Configuration is as simple as providing values for these four properties:

| Property | Type | Description |
|-------------------|------------------------------------------|-------------|
| provider | "npx prisma-generator-entityframework" | Tell prisma you want to use this generator.
| output | string: relative or absolute path | Tell prisma where you want the source code to be dumped to.
| namespace | string | Tell prisma-generator-entityframework what namespace to stick your client and model code in.
| clientClassName | string | Tell prisma-generator-entityframework what to name your DbContext subclass.

Compatibility

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| Platform | Version | Support |
|----------------|---------|----------------|
| .NET core | 5.0+ | ✔️ |
| .NET core | <5.0 | ❔ (unverified) |
| .NET framework | * | ❌ |

Right now, the primary target is .NET core, version 5.0 and later. If ~~enough~~ _any_ interest is communicated in suppporting .NET framework, it can certainly be prioritized.

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| Prisma connector | Supported | .NET core provider mapping |
|-------------------|-----------|--------------------------------------------------------------------------------------------------------------------|
| postgres | ✔️ | Npgsql.EntityFrameworkCore.PostgreSQL |
| mysql | ✔️ | Pomelo.EntityFrameworkCore.MySql |
| sqlite | ✔️ | Microsoft.EntityFrameworkCore.Sqlite |
| sqlserver | ✔️ | Microsoft.EntityFrameworkCore.SqlServer |
| cockroachdb | ❌ | -* |
| mongodb | ❌ | -


\ It seems at least plausible to support CockroachDB, and given how compelling a product the CockroachLabs team have created, this should probably prioritized.*

For more information on EntityFramework database provider support, visit the DbContext configuration guide.

For more information on Prisma-supported database connectors, visit the Prisma database connector documentation.

Feature support

The following table tracks feature availability. It's a good reference for verifying whether your schema will output with the information you need. Drop an issue if you'd like to see a specific feature prioritizied.

| Feature | Supported | Description
|--------------------------------------|-----------|--------------------------------------------------------------------------------------------------------------------------------------------------
| model generation | ✔️ | The system can generate basic models.
| client generation | ✔️ | The system can generate a basic client (DbContext in the EntityFramework world).
| .env datasource | ✔️ | The system can optionally configure the client from a .env file using the env() expression
| relation generation | ✔️ | The system can generate the code necessary to have object-to-object relations.
| table/field mapping | ✔️ | The system can detect @map and @@map annotations, and apply them accordingly.
| array-type field mapping | ✔️ | The system can detect whether a particular field is an array type.
| @id mapping | ✔️ | The system can map a primary key.
| multi-field @id mapping | ✔️ | The system can handle multi-field primary keys.
| @default(uuid()) annotation mapping | ✔️ | The system can specify a limited set of default values for primary key types: integer && string uuid.
| @db.UniqueIdentifier, @db.Uuid | ✔️ | The system can handle system-specific UUID (aka GUID) types.
| @db* annotation mapping (postgres) | ✔️ | The system can tell EntityFramework that your postgres @db annotations correspond to important underlying type mappings.
| Basic Json type mapping | ✔️ | The system can retrieve Json as a string type.\*
| Bytes type mapping | ✔️ | The system can handle the Bytes type as a byte[]
| Unsupported type mapping | ❌ | " " "
| @default annotation mapping | ❌ | The system cannot yet apply the full range of model annotations based on the @default field annotation.
| @db annotation mapping | ❌ | The system cannot yet apply the full range of model annotations based on the @db. and @dbgenerated field annotations, beyond postgres.
| property/class case formating | ❌ | The system cannot yet massage case conventions, ie camelCase to PascalCase.
| @index annotation mapping | ❌ | " " "
| @ignore annotation mapping | ❌ | " " "
| cuid/autoincrement/now | ❌ | " " ". Note that uuid is implemented for primary keys.
| nuget dependency detection | ❌ | The system cannot yet autodetect that a nuget dependency is necessary to support the declared db provider.
| enums generation | ❌ | The system cannot yet derive enums.
| schema model argument mapping | ❌ | The system cannot yet handle model argument mapping.


\ In the future, support may be added for extracting structured types out of json & jsonb` fields.*

Additional Links

- EntityFramework 6 documentation
- Prisma Schema Reference
- DbContext configuration guide
- Prisma database connector documentation
- Microsoft.EntityFrameworkCore.SqlServer
- Npgsql.EntityFrameworkCore.PostgreSQL
- Pomelo.EntityFrameworkCore.MySql
- Microsoft.EntityFrameworkCore.Sqlite
- Yassin Eldeeb's dev.to