FORMS-14814: allow multiple file attachment

blocks/form/form.js

@@ -296,7 +296,7 @@
         input.checked = field.value === input.value;
       }
     } else {
-      input.multiple = field.type === 'file[]';
+      input.multiple = field.type === 'file[]' || field.properties?.allowMultiple;
     }
     if (field.required) {
       input.setAttribute('required', 'required');
@@ -319,6 +319,9 @@
     if (input.type === 'email') {
       input.pattern = emailPattern;
     }
+    if (input.multiple) {
+      field.type = 'file[]';
+    }
     setConstraintsMessage(element, field.constraintMessages);
     element.dataset.required = field.required;
   }
@@ -510,7 +513,7 @@
         }
         return doc;
       } catch (e) {
         console.error('Unable to fetch form definition for path', pathname, path);
         return null;
       }
     });

component-models.json

@@ -1354,6 +1354,13 @@
             "name": "readOnly",
             "label": "Read-only",
             "valueType": "boolean"
+          },
+          {
+            "component": "boolean",
+            "name": "allowMultiple",
+            "label": "Allow multiple file attachments",
+            "valueType": "boolean",
+            "collapsible": false
           }
         ]
       },

models/form/_file-input.json

@@ -39,6 +39,13 @@
                     "fields": [
                         {
                             "...": "./_common.json#/basicfields"
+                        },
+                        {
+                            "component": "boolean",
+                            "name": "allowMultiple",
+                            "label": "Allow multiple file attachments",
+                            "valueType": "boolean",
+                            "collapsible": false
                         }
                     ]
                 },