Adding support for dynamic update methods. (#6)

* Added support for 'updates' being a method.

* Added test case for new update method handling

* Minor changes

* Added example

README.md

@@ -27,7 +27,7 @@ yarn add final-form-calculate
 ## Usage
 
 ```js
-import { createForm } from 'final-form'
+import { createForm, getIn } from 'final-form'
 import createDecorator from 'final-form-calculate'
 
 // Create Form
@@ -50,6 +50,20 @@ const decorator = createDecorator(
       total: (itemValue, allValues) =>
         (allValues.items || []).reduce((sum, value) => sum + value, 0)
     }
+  },
+  {
+    field: /\.timeFrom/, // when a deeper field matching this pattern changes...
+    updates: (value, name, allValues) => {
+      const toField = name.replace('timeFrom', 'timeTo')
+      const toValue = getIn(allValues, toField)
+      if (toValue && value > toValue) {
+        return {
+          [toField]: value
+        }
+      }
+
+      return {}
+    }
   }
 )
 

src/decorator.js

@@ -14,10 +14,17 @@ const createDecorator = (...calculations: Calculation[]): Decorator => (
           const next = getIn(values, field)
           const previous = getIn(previousValues, field)
           if (next !== previous) {
-            Object.keys(updates).forEach(destField => {
-              const update = updates[destField]
-              form.change(destField, update(next, values))
-            })
+            if (typeof updates === 'function') {
+              const results = updates(next, field, values)
+              Object.keys(results).forEach(destField => {
+                form.change(destField, results[destField])
+              })
+            } else {
+              Object.keys(updates).forEach(destField => {
+                const update = updates[destField]
+                form.change(destField, update(next, values))
+              })
+            }
           }
         }
         const fields = form.getRegisteredFields()

src/decorator.test.js

@@ -204,4 +204,78 @@ describe('decorator', () => {
     expect(spy.mock.calls[5][0].values).toEqual({ items: [3, 4, 5], total: 7 })
     expect(spy.mock.calls[6][0].values).toEqual({ items: [3, 4, 5], total: 12 })
   })
+
+  it('should allow seperate array summing', () => {
+    const form = createForm({ onSubmit: onSubmitMock })
+    const spy = jest.fn()
+    const total = jest.fn()
+    const sum = jest.fn((itemValue, allValues) =>
+      (allValues.list[0].items || []).reduce((sum, item) => sum + item, 0)
+    )
+    form.subscribe(spy, { values: true })
+    form.registerField('list[0].items[0]', () => {}, {})
+    form.registerField('list[0].items[1]', () => {}, {})
+    form.registerField('list[0].items[2]', () => {}, {})
+    form.registerField('list[0].total', total, { value: true })
+    const decorator = createDecorator({
+      field: /\.items\[\d+\]/,
+      updates: (value, name, all) => {
+        const totalField = name.replace(/items\[[0-9]+\]/, 'total')
+        return {
+          [totalField]: sum(value, all)
+        }
+      }
+    })
+    decorator(form)
+
+    expect(spy).toHaveBeenCalled()
+    expect(spy).toHaveBeenCalledTimes(1)
+    expect(spy.mock.calls[0][0].values).toEqual({})
+
+    expect(total).toHaveBeenCalled()
+    expect(total).toHaveBeenCalledTimes(1)
+    expect(total.mock.calls[0][0].value).toBeUndefined()
+
+    expect(sum).not.toHaveBeenCalled()
+
+    // change first item value
+    form.change('list[0].items[0]', 3)
+
+    expect(sum).toHaveBeenCalled()
+    expect(sum).toHaveBeenCalledTimes(1)
+
+    expect(spy).toHaveBeenCalledTimes(3)
+    expect(spy.mock.calls[1][0].values).toEqual({ list: [{ items: [3] }] })
+    expect(spy.mock.calls[2][0].values).toEqual({
+      list: [{ items: [3], total: 3 }]
+    })
+
+    // change second item value
+    form.change('list[0].items[1]', 4)
+
+    expect(sum).toHaveBeenCalled()
+    expect(sum).toHaveBeenCalledTimes(2)
+
+    expect(spy).toHaveBeenCalledTimes(5)
+    expect(spy.mock.calls[3][0].values).toEqual({
+      list: [{ items: [3, 4], total: 3 }]
+    })
+    expect(spy.mock.calls[4][0].values).toEqual({
+      list: [{ items: [3, 4], total: 7 }]
+    })
+
+    // change third item value
+    form.change('list[0].items[2]', 5)
+
+    expect(sum).toHaveBeenCalled()
+    expect(sum).toHaveBeenCalledTimes(3)
+
+    expect(spy).toHaveBeenCalledTimes(7)
+    expect(spy.mock.calls[5][0].values).toEqual({
+      list: [{ items: [3, 4, 5], total: 7 }]
+    })
+    expect(spy.mock.calls[6][0].values).toEqual({
+      list: [{ items: [3, 4, 5], total: 12 }]
+    })
+  })
 })