Adds support for deterministic ids

src/Formulate.js

@@ -51,9 +51,11 @@ class Formulate {
       uploadJustCompleteDuration: 1000,
       errorHandler: (err) => err,
       plugins: [ en ],
-      locales: {}
+      locales: {},
+      idPrefix: 'formulate-'
     }
     this.registry = new Map()
+    this.idRegistry = {}
   }
 
   /**
@@ -73,6 +75,21 @@ class Formulate {
     }
   }
 
+  /**
+   * Produce a deterministically generated id based on the sequence by which it
+   * was requested. This should be *theoretically* the same SSR as client side.
+   * However, SSR and deterministic ids can be very challenging, so this
+   * implementation is open to community review.
+   */
+  nextId (vm) {
+    const path = vm.$route && vm.$route.path && vm.$route.path || false
+    const pathPrefix = path ? vm.$route.path.replace(/[\/\\.\s]/g, '-') : 'global';
+    if (!Object.prototype.hasOwnProperty.call(this.idRegistry, pathPrefix)) {
+      this.idRegistry[pathPrefix] = 0;
+    }
+    return `${this.options.idPrefix}${pathPrefix}-${++this.idRegistry[pathPrefix]}`
+  }
+
   /**
    * Given a set of options, apply them to the pre-existing options.
    * @param {Object} extendWith

src/FormulateInput.vue

@@ -190,7 +190,7 @@ export default {
   },
   data () {
     return {
-      defaultId: nanoid(9),
+      defaultId: this.$formulate.nextId(this),
       localAttributes: {},
       internalModelProxy: this.getInitialValue(),
       behavioralErrorVisibility: (this.errorBehavior === 'live'),

test/unit/FormulateInputBox.test.js

@@ -207,4 +207,12 @@ describe('FormulateInputBox', () => {
     expect(wrapper.contains(FormulateInputGroup)).toBe(true)
     expect(wrapper.find('input[type="checkbox"]').exists()).toBe(false)
   })
+
+  it('renders multiple labels both with correct id', async () => {
+    const wrapper = mount(FormulateInput, { propsData: { type: 'checkbox', label: 'VueFormulate FTW!'} })
+    const id = wrapper.find('input[type="checkbox"]').attributes('id')
+    const labelIds = wrapper.findAll('label').wrappers.map(label => label.attributes('for'));
+    expect(labelIds.length).toBe(2);
+    expect(labelIds.filter(labelId => labelId === id).length).toBe(2);
+  })
 })