From 9be6e0f386547c7b5a58eedd3566bbfa6a63fece Mon Sep 17 00:00:00 2001
From: Javier Gonzalez <xaviergonz@gmail.com>
Date: Fri, 7 May 2021 23:36:17 +0200
Subject: [PATCH] generic types are now inferable from constructor params

---
 CHANGELOG.md                                 |  4 +++
 packages/lib/package.json                    |  2 +-
 packages/lib/src/modelShared/prop.ts         | 11 +++---
 packages/lib/test/model/defaultProps.test.ts |  5 +++
 packages/lib/test/model/subclassing.test.ts  | 35 +++++++++++---------
 5 files changed, 34 insertions(+), 23 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d2876c5e..0dfbdac6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Change Log
 
+## 0.58.2
+
+- Generic types are now inferable from the constructor parameters
+
 ## 0.58.1
 
 - Fixed an issue where `idProp` on the base was not being picked up by `ExtendedModel`.
diff --git a/packages/lib/package.json b/packages/lib/package.json
index 9d6f36c0..54af4437 100644
--- a/packages/lib/package.json
+++ b/packages/lib/package.json
@@ -1,6 +1,6 @@
 {
   "name": "mobx-keystone",
-  "version": "0.58.1",
+  "version": "0.58.2",
   "description": "A MobX powered state management solution based on data trees with first class support for Typescript, snapshots, patches and much more",
   "keywords": [
     "mobx",
diff --git a/packages/lib/src/modelShared/prop.ts b/packages/lib/src/modelShared/prop.ts
index bc679db2..2db3bd76 100644
--- a/packages/lib/src/modelShared/prop.ts
+++ b/packages/lib/src/modelShared/prop.ts
@@ -52,12 +52,11 @@ export type ModelPropsToData<MP extends ModelProps> = {
 }
 
 // we don't use O.Optional anymore since it generates unions too heavy
-export type ModelPropsToCreationData<MP extends ModelProps> = O.Pick<
-  {
-    [k in keyof MP]?: MP[k]["$creationValueType"]
-  },
-  OptionalModelProps<MP>
-> &
+// also if we use pick over the optional props we will loose the ability
+// to infer generics
+export type ModelPropsToCreationData<MP extends ModelProps> = {
+  [k in keyof MP]?: MP[k]["$creationValueType"]
+} &
   O.Omit<
     {
       [k in keyof MP]: MP[k]["$creationValueType"]
diff --git a/packages/lib/test/model/defaultProps.test.ts b/packages/lib/test/model/defaultProps.test.ts
index fa6f5cf1..6af39ed0 100644
--- a/packages/lib/test/model/defaultProps.test.ts
+++ b/packages/lib/test/model/defaultProps.test.ts
@@ -51,6 +51,11 @@ test("default props", () => {
 
       bb?: number
       bbbb?: number | null
+
+      a?: number
+      aaa?: number | null
+      b?: number
+      bbb?: number | null
     } & {
       a: number
       aaa: number | null
diff --git a/packages/lib/test/model/subclassing.test.ts b/packages/lib/test/model/subclassing.test.ts
index 4c96eb45..47597ff2 100644
--- a/packages/lib/test/model/subclassing.test.ts
+++ b/packages/lib/test/model/subclassing.test.ts
@@ -86,11 +86,12 @@ test("subclassing with additional props", () => {
       x?: number | null
       y?: number | null
       z?: number | null
-    } & Empty & {
-        a?: number | null
-      } & {
-        b: number
-      }
+    } & {
+      a?: number | null
+      b?: number
+    } & {
+      b: number
+    } & Empty
   )
 
   const p2 = new P2({ x: 20, b: 70 })
@@ -300,11 +301,11 @@ test("three level subclassing", () => {
       x?: number | null | undefined
       y?: number | null | undefined
       z?: number | null | undefined
-    } & Empty & {
-        a?: number | null | undefined
-      } & {
-        b: number
-      }
+    } & {
+      a?: number | null | undefined
+    } & { b?: number } & {
+      b: number
+    } & Empty
   )
 
   const p2 = new P2({ x: 20, b: 70 })
@@ -697,21 +698,22 @@ test("ExtendedModel should bring static / prototype properties", () => {
 test("new pattern for generics", () => {
   @model("GenericModel")
   class GenericModel<T1, T2> extends Model(<U1, U2>() => ({
-    v1: prop<U1>(),
+    v1: prop<U1 | undefined>(),
     v2: prop<U2>(),
     v3: prop<number>(0),
   }))<T1, T2> {}
 
   assert(
     _ as ModelData<GenericModel<string, number>>,
-    _ as { [modelIdKey]: string; v1: string; v2: number; v3: number }
+    _ as { [modelIdKey]: string; v1: string | undefined; v2: number; v3: number }
   )
   assert(
     _ as ModelData<GenericModel<number, string>>,
-    _ as { [modelIdKey]: string; v1: number; v2: string; v3: number }
+    _ as { [modelIdKey]: string; v1: number | undefined; v2: string; v3: number }
   )
 
-  const s = new GenericModel<string, number>({ v1: "1", v2: 2, v3: 3 })
+  const s = new GenericModel({ v1: "1", v2: 2, v3: 3 })
+  assert(s, _ as GenericModel<string, number>)
   expect(s.v1).toBe("1")
   expect(s.v2).toBe(2)
   expect(s.v3).toBe(3)
@@ -720,11 +722,12 @@ test("new pattern for generics", () => {
   class ExtendedGenericModel<T1, T2> extends ExtendedModel(<T1, T2>() => ({
     baseModel: modelClass<GenericModel<T1, T2>>(GenericModel),
     props: {
-      v4: prop<T2>(),
+      v4: prop<T2 | undefined>(),
     },
   }))<T1, T2> {}
 
-  const e = new ExtendedGenericModel<string, number>({ v1: "1", v2: 2, v3: 3, v4: 4 })
+  const e = new ExtendedGenericModel({ v1: "1", v2: 2, v3: 3, v4: 4 })
+  assert(e, _ as ExtendedGenericModel<string, number>)
   expect(e.v1).toBe("1")
   expect(e.v2).toBe(2)
   expect(e.v3).toBe(3)