Support boolean and string fields

- Pass existing data to the API form to pre-populate

lib/api_form.dart

@@ -1,7 +1,10 @@
 import 'dart:convert';
 
 import 'package:InvenTree/api.dart';
-
+import 'package:InvenTree/widget/dialogs.dart';
+import 'package:InvenTree/widget/fields.dart';
+import 'package:flutter/cupertino.dart';
+import 'package:flutter/material.dart';
 
 /*
  * Class that represents a single "form field",
@@ -24,13 +27,71 @@ class APIFormField {
   // Is this field read only?
   bool get readOnly => (data['read_only'] ?? false) as bool;
 
+  // Get the "value" as a string (look for "default" if not available)
+  dynamic get value => (data['value'] ?? data['default']);
+
+  // Get the "default" as a string
+  dynamic get defaultValue => data['default'];
+
+  // Return the error message associated with this field
+  String get errorMessage => data['error'];
+
   // Is this field required?
   bool get required => (data['required'] ?? false) as bool;
 
-  String get label => (data['label'] ?? '') as String;
+  String get type => (data['type'] ?? '').toString();
 
-  String get helpText => (data['help_text'] ?? '') as String;
+  String get label => (data['label'] ?? '').toString();
 
+  String get helpText => (data['help_text'] ?? '').toString();
+
+  // Construct a widget for this input
+  Widget constructField() {
+    switch (type) {
+      case "string":
+        return _constructString();
+      case "boolean":
+        return _constructBoolean();
+      default:
+        return ListTile(
+          title: Text("Unsupported field type: '${type}'")
+        );
+    }
+  }
+
+  // Consturct a string input element
+  Widget _constructString() {
+
+    return TextFormField(
+      decoration: InputDecoration(
+        labelText: required ? label + "*" : label,
+        hintText: helpText,
+      ),
+      initialValue: value ?? '',
+      onSaved: (val) {
+        data["value"] = val;
+        print("${name} -> ${val}");
+      },
+      validator: (value) {
+
+        // TODO - Custom field validation
+      },
+    );
+  }
+
+  // Construct a boolean input element
+  Widget _constructBoolean() {
+
+    return CheckBoxField(
+      label: label,
+      hint: helpText,
+      initial: value,
+      onSaved: (val) {
+        data['value'] = val;
+        print("${name} -> ${val}");
+      },
+    );
+  }
 }
 
 
@@ -56,9 +117,15 @@ Map<String, dynamic> extractFields(dynamic options) {
  * Launch an API-driven form,
  * which uses the OPTIONS metadata (at the provided URL)
  * to determine how the form elements should be rendered!
+ *
+ * @param title is the title text to display on the form
+ * @param url is the API URl to make the OPTIONS request to
+ * @param fields is a map of fields to display (with optional overrides)
+ * @param modelData is the (optional) existing modelData
+ * @param method is the HTTP method to use to send the form data to the server (e.g. POST / PATCH)
  */
 
-Future<bool> launchApiForm(String url, Map<String, dynamic> fields, {String method = "PATCH"}) async {
+Future<bool> launchApiForm(String title, String url, Map<String, dynamic> fields, {Map<String, dynamic> modelData = const {}, String method = "PATCH"}) async {
 
   dynamic options = await InvenTreeAPI().options(url);
 
@@ -103,12 +170,30 @@ Future<bool> launchApiForm(String url, Map<String, dynamic> fields, {String meth
       }
     }
 
+    // Update fields with existing model data
+    for (String key in modelData.keys) {
+
+      dynamic value = modelData[key];
+
+      if (availableFields.containsKey(key)) {
+        availableFields[key]['value'] = value;
+      }
+    }
+
     formFields.add(APIFormField(fieldName, remoteField));
   }
 
+  List<Widget> widgets = [];
+
   for (var ff in formFields) {
-    print("${ff.name} -> ${ff.label} (${ff.helpText})");
+    widgets.add(ff.constructField());
   }
 
+  final formKey = new GlobalKey<FormState>();
+
+  showFormDialog(title, fields: widgets, key: formKey, callback: () {
+    print("submitted, I guess?");
+  });
+
   return true;
 }