update:class增加when方法

extend/catcher/generate/build/classes/Classes.php

@@ -97,4 +97,21 @@ class Classes
 
         return $this;
     }
+
+    /**
+     * when
+     *
+     * @time 2020年11月19日
+     * @param $condition
+     * @param \Closure $closure
+     * @return $this
+     */
+    public function when($condition, \Closure $closure)
+    {
+        if ($condition) {
+            $closure($this);
+        }
+
+        return $this;
+    }
 }

extend/catcher/generate/factory/Model.php

@@ -83,11 +83,13 @@ class Model extends Factory
                                 (new Property('name'))->default($table)->docComment('// 表名')
                             );
 
-                            $class->addProperty(
-                                (new Property('field'))->default(
-                                    (new Arr)->build(Db::getFields($table))
-                                )->docComment('// 数据库字段映射')
-                            );
+                            $class->when($this->hasTableExists($table), function ($class) use ($table){
+                                $class->addProperty(
+                                    (new Property('field'))->default(
+                                        (new Arr)->build(Db::getFields($table))
+                                    ))->docComment('// 数据库字段映射');
+                            });
+
                         })->getContent();
     }
 }