refactor: CFormFile: reduce custom prop logic

Reduce custom prop to boolean, and add new placeholder property

Author: woothu

src/components/Form/CFormFile.vue

@@ -26,7 +26,7 @@
         :for="safeId"
         class="c-custom-file-label"
       >
-        {{placeholder}}
+        {{computedPlaceholder}}
       </label>
     </template>
 
@@ -71,7 +71,7 @@ export default {
   //     default: null
   //   },
   //   multiple: Boolean,
-  //   custom: [Boolean, String],
+  //   custom: Boolean,
   //   addInputClasses: String,
   //   addLabelClasses: String,
   //   addWrapperClasses: String,
@@ -82,18 +82,12 @@ export default {
     }
   },
   computed: {
-    placeholder () {
-      return typeof this.custom === 'string' ?
-                      this.custom : this.multiple ?
-                        'Choose files...' : 'Choose file...'
+    computedPlaceholder () {
+      return this.placeholder || `Choose file${this.multiple ?'s':''}...`
     },
     // classesComputedProps mixin
-    haveCustomSize () {
-      return ['','sm','lg'].includes(this.size) &&
-             Boolean(this.size && !this.custom)
-    },
     // haveCustomSize () {
-    //   return ['','sm','lg'].includes(this.size) && Boolean(this.size)
+    //   return ['sm','lg'].includes(this.size)
     // },
     computedClasses () {
       return [

src/components/Form/formProps.js

@@ -44,10 +44,11 @@ const textInputsProps = {
   }
 }
 
-// Html props: disabled, required, accept, id
+// Html props: disabled, required, accept, id, placeholder
 export const formFileProps = Object.assign(
   {}, formGroupAlwaysSharedProps, props, {
-  custom: [Boolean, String],
+  custom: Boolean,
+  placeholder: String,
   multiple: Boolean
 })
 
@@ -91,6 +92,6 @@ export const formCheckboxProps = Object.assign(
     type: [String, Number],
     default: undefined
   },
-  custom: [Boolean, String],
+  custom: Boolean,
   inline: Boolean
 })