Merge pull request #1410 from mobxjs/custom-type-env

[CustomType] Add 'environment' as second argument for options.fromSnapshot

Author: mweststrate

packages/mobx-state-tree/__tests__/core/custom-type.test.ts

@@ -30,7 +30,8 @@ class Decimal {
 {
     const DecimalPrimitive = types.custom<string, Decimal>({
         name: "Decimal",
-        fromSnapshot(value: string) {
+        fromSnapshot(value: string, env: any) {
+            if (env && env.test) env.test(value)
             return new Decimal(value)
         },
         toSnapshot(value: Decimal) {
@@ -106,6 +107,12 @@ class Decimal {
         p.stop()
         expect(p.patches).toMatchSnapshot()
     })
+
+    test("passes environment to fromSnapshot", () => {
+        const env = { test: jest.fn() }
+        Wallet.create({ balance: "3.0" }, env)
+        expect(env.test).toBeCalledWith("3.0")
+    })
 }
 
 {

packages/mobx-state-tree/src/types/utility-types/custom.ts

@@ -13,8 +13,8 @@ import {
 export interface CustomTypeOptions<S, T> {
     /** Friendly name */
     name: string
-    /** given a serialized value, how to turn it into the target type */
-    fromSnapshot(snapshot: S): T
+    /** given a serialized value and environment, how to turn it into the target type */
+    fromSnapshot(snapshot: S, env?: any): T
     /** return the serialization of the current value */
     toSnapshot(value: T): S
     /** if true, this is a converted value, if false, it's a snapshot */
@@ -33,8 +33,8 @@ export interface CustomTypeOptions<S, T> {
  * export interface CustomTypeOptions<S, T> {
  *     // Friendly name
  *     name: string
- *     // given a serialized value, how to turn it into the target type
- *     fromSnapshot(snapshot: S): T
+ *     // given a serialized value and environment, how to turn it into the target type
+ *     fromSnapshot(snapshot: S, env: any): T
  *     // return the serialization of the current value
  *     toSnapshot(value: T): S
  *     // if true, this is a converted value, if false, it's a snapshot
@@ -116,7 +116,7 @@ export class CustomType<S, T> extends SimpleType<S | T, S, T> {
     ): this["N"] {
         const valueToStore: T = this.options.isTargetType(initialValue)
             ? (initialValue as T)
-            : this.options.fromSnapshot(initialValue as S)
+            : this.options.fromSnapshot(initialValue as S, parent && parent.root.environment)
         return createScalarNode(this, parent, subpath, environment, valueToStore)
     }
 
@@ -132,7 +132,9 @@ export class CustomType<S, T> extends SimpleType<S | T, S, T> {
                 return current
             }
         }
-        const valueToStore: T = isSnapshot ? this.options.fromSnapshot(value as S) : (value as T)
+        const valueToStore: T = isSnapshot
+            ? this.options.fromSnapshot(value as S, parent.root.environment)
+            : (value as T)
         const newNode = this.instantiate(parent, subpath, undefined, valueToStore)
         current.die() // noop if detaching
         return newNode