feat: Allow custom client location

This breaks the type & runtime dependency on a hardcoded
`@prisma/client` client output location, allowing
custom location (eg when having multiple clients).

This adds a layer of runtime safety to validate the DMMF,
which can now be passed in the configuration,
allowing all sorts of runtime hacks.

See #18 & #19.

README.md

@@ -247,6 +247,21 @@ _Tip: the current encryption key is already part of the decryption keys, no need
 Key rotation on existing fields (decrypt with old key and re-encrypt with the
 new one) is done by [data migrations](#migrations).
 
+## Custom Prisma Client Location
+
+If you are generating your Prisma client to a custom location, you'll need to
+tell the middleware where to look for the DMMF _(the internal AST generated by Prisma that we use to read those triple-slash comments)_:
+
+```ts
+import { Prisma } from '../my/prisma/client'
+
+prismaClient.$use(
+  fieldEncryptionMiddleware({
+    dmmf: Prisma.dmmf
+  })
+)
+```
+
 **Roadmap:**
 
 - [x] Provide multiple decryption keys

package.json

@@ -33,15 +33,14 @@
     "postbuild": "chmod +x ./dist/generator/main.js && cd node_modules/.bin && ln -sf ../../dist/generator/main.js ./prisma-field-encryption",
     "generate": "run-s generate:*",
     "generate:prisma": "prisma generate",
-    "generate:dmmf": "ts-node ./src/scripts/generateDMMF.ts",
     "test": "run-s test:**",
     "test:types": "tsc --noEmit",
     "test:unit": "jest --config jest.config.unit.json",
     "pretest:integration": "cp -f ./prisma/db.test.sqlite ./prisma/db.integration.sqlite",
     "test:integration": "jest --config jest.config.integration.json --runInBand",
     "test:coverage:merge": "nyc merge ./coverage ./coverage/coverage-final.json",
     "test:coverage:report": "nyc report -t ./coverage --r html -r lcov -r clover",
-    "ci": "run-s generate build test",
+    "ci": "run-s build test",
     "prepare": "husky install",
     "premigrate": "run-s build generate",
     "migrate": "ts-node ./src/tests/migrate.ts"
@@ -50,14 +49,15 @@
     "@47ng/cloak": "^1.1.0-beta.2",
     "@prisma/generator-helper": "^3.13.0",
     "immer": "^9.0.12",
-    "object-path": "^0.11.8"
+    "object-path": "^0.11.8",
+    "zod": "^3.15.1"
   },
   "peerDependencies": {
     "@prisma/client": "^3.8.0"
   },
   "devDependencies": {
     "@commitlint/config-conventional": "^16.2.4",
-    "@prisma/client": "^3.13.0",
+    "@prisma/client": "3.13.0",
     "@prisma/sdk": "^3.13.0",
     "@types/jest": "^27.4.1",
     "@types/node": "^17.0.29",

prisma/schema.prisma

@@ -6,6 +6,7 @@ datasource db {
 generator client {
   provider        = "prisma-client-js"
   previewFeatures = ["interactiveTransactions"]
+  output          = "../src/tests/.generated/client"
 }
 
 // generator fieldEncryptionMigrations {

src/dmmf.ts

@@ -1,6 +1,5 @@
-import { Prisma } from '@prisma/client'
 import { errors, warnings } from './errors'
-import type { DMMF, FieldConfiguration } from './types'
+import { DMMFDocument, dmmfDocumentParser, FieldConfiguration } from './types'
 
 export interface ConnectionDescriptor {
   modelName: string
@@ -23,13 +22,8 @@ export type DMMFModels = Record<string, DMMFModelDescriptor> // key: model name
 
 const supportedCursorTypes = ['Int', 'String']
 
-export function analyseDMMF(dmmf: DMMF = Prisma.dmmf): DMMFModels {
-  // todo: Make it robust against changes in the DMMF structure
-  // (can happen as it's an undocumented API)
-  // - Prisma.dmmf does not exist
-  // - Models are not located there, or empty -> warning
-  // - Model objects don't conform to what we need (parse with zod)
-
+export function analyseDMMF(input: DMMFDocument): DMMFModels {
+  const dmmf = dmmfDocumentParser.parse(input)
   const allModels = dmmf.datamodel.models
 
   return allModels.reduce<DMMFModels>((output, model) => {

src/encryption.ts

@@ -59,8 +59,8 @@ const writeOperations = [
 
 const whereClauseRegExp = /\.where\./
 
-export function encryptOnWrite(
-  params: MiddlewareParams,
+export function encryptOnWrite<Models extends string, Actions extends string>(
+  params: MiddlewareParams<Models, Actions>,
   keys: KeysConfiguration,
   models: DMMFModels,
   operation: string
@@ -71,42 +71,45 @@ export function encryptOnWrite(
 
   const encryptionErrors: string[] = []
 
-  const mutatedParams = produce(params, (draft: Draft<MiddlewareParams>) => {
-    visitInputTargetFields(
-      draft,
-      models,
-      function encryptFieldValue({
-        fieldConfig,
-        value: clearText,
-        path,
-        model,
-        field
-      }) {
-        if (!fieldConfig.encrypt) {
-          return
-        }
-        if (whereClauseRegExp.test(path)) {
-          console.warn(warnings.whereClause(operation, path))
-        }
-        try {
-          const cipherText = encryptStringSync(clearText, keys.encryptionKey)
-          objectPath.set(draft.args, path, cipherText)
-        } catch (error) {
-          encryptionErrors.push(
-            errors.fieldEncryptionError(model, field, path, error)
-          )
+  const mutatedParams = produce(
+    params,
+    (draft: Draft<MiddlewareParams<Models, Actions>>) => {
+      visitInputTargetFields(
+        draft,
+        models,
+        function encryptFieldValue({
+          fieldConfig,
+          value: clearText,
+          path,
+          model,
+          field
+        }) {
+          if (!fieldConfig.encrypt) {
+            return
+          }
+          if (whereClauseRegExp.test(path)) {
+            console.warn(warnings.whereClause(operation, path))
+          }
+          try {
+            const cipherText = encryptStringSync(clearText, keys.encryptionKey)
+            objectPath.set(draft.args, path, cipherText)
+          } catch (error) {
+            encryptionErrors.push(
+              errors.fieldEncryptionError(model, field, path, error)
+            )
+          }
         }
-      }
-    )
-  })
+      )
+    }
+  )
   if (encryptionErrors.length > 0) {
     throw new Error(errors.encryptionErrorReport(operation, encryptionErrors))
   }
   return mutatedParams
 }
 
-export function decryptOnRead(
-  params: MiddlewareParams,
+export function decryptOnRead<Models extends string, Actions extends string>(
+  params: MiddlewareParams<Models, Actions>,
   result: any,
   keys: KeysConfiguration,
   models: DMMFModels,

src/errors.ts

@@ -1,4 +1,4 @@
-import type { Prisma } from '@prisma/client'
+import type { DMMFField, DMMFModel } from './types'
 
 const header = '[prisma-field-encryption]'
 
@@ -8,7 +8,7 @@ const prefixWarning = (input: string) => `${header} Warning: ${input}`
 export const errors = {
   // Setup errors
   noEncryptionKey: prefixError('no encryption key provided.'),
-  unsupportedFieldType: (model: Prisma.DMMF.Model, field: Prisma.DMMF.Field) =>
+  unsupportedFieldType: (model: DMMFModel, field: DMMFField) =>
     prefixError(
       `encryption enabled for field ${model.name}.${field.name} of unsupported type ${field.type}: only String fields can be encrypted.`
     ),

src/generator/runtime/visitRecords.ts

@@ -1,26 +1,25 @@
-import type { PrismaClient } from '@prisma/client'
 import { defaultProgressReport, ProgressReportCallback } from './progressReport'
 
-export type RecordVisitor<Cursor> = (
+export type RecordVisitor<PrismaClient, Cursor> = (
   client: PrismaClient,
   cursor: Cursor | undefined
 ) => Promise<Cursor | undefined>
 
-export interface VisitRecordsArgs<Cursor> {
+export interface VisitRecordsArgs<PrismaClient, Cursor> {
   modelName: string
   client: PrismaClient
   getTotalCount: () => Promise<number>
-  migrateRecord: RecordVisitor<Cursor>
+  migrateRecord: RecordVisitor<PrismaClient, Cursor>
   reportProgress?: ProgressReportCallback
 }
 
-export async function visitRecords<Cursor>({
+export async function visitRecords<PrismaClient, Cursor>({
   modelName,
   client,
   getTotalCount,
   migrateRecord,
   reportProgress = defaultProgressReport
-}: VisitRecordsArgs<Cursor>) {
+}: VisitRecordsArgs<PrismaClient, Cursor>) {
   const totalCount = await getTotalCount()
   if (totalCount === 0) {
     return 0

src/index.ts

@@ -2,17 +2,20 @@ import { analyseDMMF } from './dmmf'
 import { configureKeys, decryptOnRead, encryptOnWrite } from './encryption'
 import type { Configuration, Middleware, MiddlewareParams } from './types'
 
-export function fieldEncryptionMiddleware(
-  config: Configuration = {}
-): Middleware {
+export function fieldEncryptionMiddleware<
+  Models extends string = any,
+  Actions extends string = any
+>(config: Configuration = {}): Middleware<Models, Actions> {
   // This will throw if the encryption key is missing
   // or if anything is invalid.
   const keys = configureKeys(config)
-  const models = analyseDMMF()
+  const models = analyseDMMF(
+    config.dmmf ?? require('@prisma/client').Prisma.dmmf
+  )
 
   return async function fieldEncryptionMiddleware(
-    params: MiddlewareParams,
-    next: (params: MiddlewareParams) => Promise<any>
+    params: MiddlewareParams<Models, Actions>,
+    next: (params: MiddlewareParams<Models, Actions>) => Promise<any>
   ) {
     if (!params.model) {
       // Unsupported operation

src/tests/.generated/.gitignore

@@ -0,0 +1 @@
+client/

src/tests/prismaClient.ts

@@ -1,5 +1,5 @@
-import { PrismaClient } from '@prisma/client'
 import { fieldEncryptionMiddleware } from '../index'
+import { Prisma, PrismaClient } from './.generated/client'
 
 export const TEST_ENCRYPTION_KEY =
   'k1.aesgcm256.OsqVmAOZBB_WW3073q1wU4ag0ap0ETYAYMh041RuxuI='
@@ -33,7 +33,8 @@ client.$use(async (params, next) => {
 
 client.$use(
   fieldEncryptionMiddleware({
-    encryptionKey: TEST_ENCRYPTION_KEY
+    encryptionKey: TEST_ENCRYPTION_KEY,
+    dmmf: Prisma.dmmf
   })
 )
 

src/types.ts

@@ -1,16 +1,66 @@
-import { Prisma } from '@prisma/client'
+/**
+ * Prisma types --
+ *
+ * We're copying just what we need for local type safety
+ * without importing Prisma-generated types, as the location
+ * of the generated client can be unknown (when using custom
+ * or multiple client locations).
+ */
 
-// Prisma types --
+import { z } from 'zod'
 
-export type MiddlewareParams = Prisma.MiddlewareParams
-export type Middleware = Prisma.Middleware
-export type DMMF = typeof Prisma.dmmf
+/**
+ * Not ideal to use `any` on model & action, but Prisma's
+ * strong typing there actually prevents using the correct
+ * type without excessive generics wizardry.
+ */
+export type MiddlewareParams<Models extends string, Actions extends string> = {
+  model?: Models
+  action: Actions
+  args: any
+  dataPath: string[]
+  runInTransaction: boolean
+}
+
+export type Middleware<
+  Models extends string,
+  Actions extends string,
+  Result = any
+> = (
+  params: MiddlewareParams<Models, Actions>,
+  next: (params: MiddlewareParams<Models, Actions>) => Promise<Result>
+) => Promise<Result>
+
+const dmmfFieldParser = z.object({
+  name: z.string(),
+  isList: z.boolean(),
+  isUnique: z.boolean(),
+  isId: z.boolean(),
+  type: z.string(),
+  documentation: z.string().optional()
+})
+
+const dmmfModelParser = z.object({
+  name: z.string(),
+  fields: z.array(dmmfFieldParser)
+})
+
+export const dmmfDocumentParser = z.object({
+  datamodel: z.object({
+    models: z.array(dmmfModelParser)
+  })
+})
+
+export type DMMFModel = z.TypeOf<typeof dmmfModelParser>
+export type DMMFField = z.TypeOf<typeof dmmfFieldParser>
+export type DMMFDocument = z.TypeOf<typeof dmmfDocumentParser>
 
 // Internal types --
 
 export interface Configuration {
   encryptionKey?: string
   decryptionKeys?: string[]
+  dmmf?: DMMFDocument
 }
 
 export interface FieldConfiguration {

src/visitor.test.ts

@@ -36,7 +36,7 @@ describe('visitor', () => {
 
   test('visitInputTargetFields - simple example', async () => {
     const models = analyseDMMF(await dmmf)
-    const params: MiddlewareParams = {
+    const params: MiddlewareParams<any, any> = {
       action: 'create',
       model: 'User',
       args: {
@@ -63,7 +63,7 @@ describe('visitor', () => {
 
   test('visitInputTargetFields - nested create', async () => {
     const models = analyseDMMF(await dmmf)
-    const params: MiddlewareParams = {
+    const params: MiddlewareParams<any, any> = {
       action: 'create',
       model: 'User',
       args: {

src/visitor.ts

@@ -60,8 +60,11 @@ const makeVisitor = (models: DMMFModels, visitor: TargetFieldVisitorFn) =>
     return state
   }
 
-export function visitInputTargetFields(
-  params: MiddlewareParams,
+export function visitInputTargetFields<
+  Models extends string,
+  Actions extends string
+>(
+  params: MiddlewareParams<Models, Actions>,
   models: DMMFModels,
   visitor: TargetFieldVisitorFn
 ) {
@@ -70,8 +73,11 @@ export function visitInputTargetFields(
   })
 }
 
-export function visitOutputTargetFields(
-  params: MiddlewareParams,
+export function visitOutputTargetFields<
+  Models extends string,
+  Actions extends string
+>(
+  params: MiddlewareParams<Models, Actions>,
   result: any,
   models: DMMFModels,
   visitor: TargetFieldVisitorFn