芳草苑

Magento 自带的管理产品图片的机制简单有效，但每次只能对单个产品进行管理，每次要 http upload 很费时。如果换个角度看，如果要成批更新产品图片，就不那么方便；如果要调用某个产品图片，必须先找到产品才能找到图片，因为 Magento 对上传后的文件进行了 dispretion 处理了文件路径，没有直观的办法可以直接浏览图片。

所以我的做法是，产品图片按产品属性归类，把整个文件夹 ftp 到 Magento 某个位置（或从 Magento 中独立出来，用一个静态文件服务器来管理图片，这样可以提供更方便的文件操作）。

然后在 magento/media/catalog/product 下建一个软连接（假设这个软连接名 static_image_linkedin）到产品图片目录的根。不要在 magento/media/catalog 这一级把 product 建为软连接，因为 Magento 会在 product 下建 cache 目录，从静态文件服务器角度看，这个 cache 是垃圾（我追求完美）。

然后，如果要指定产品使用某图片，必须把image, small_image, thumbnail, media_gallery 对应的值保存为人工指定位置的图片路径，该值的形式如 “/static_image_linkedin/nwf/recycled/green_bag.jpg”。Magento 原值形式如 “/g/r/green_bag.jpg”，我还没做出一个 GUI 帮助完成此项修改，依赖数据库直接操作。

我本有一个想法是修改 magento/app/code/core/Mage/Catalog/Model/Product/Media/Config.php 来改变产品图片目录的根，这样就不需要建软连接。但这样做的缺点是在移交 Magento 给别的 developers 时，我还得多一点额外交代。

When to use:
Magento has a native “buy x get y” sales rule in promotions. Magento’s x and y refer to a same product. For example, if a product offer is “buy 3 get 2″, you have to buy 5 of this product then only pay for 3 of them.

Quite often the store owners want to give an offer which let customers choose from a wide range of products, (the programme add them up, get a total quantity of subselect), and offer another selection of products for free. It is useful if the store have two ranges of products, among which prices are almost the same. Let’s make it clear to you: in this module, “buy x get y” means “Buy X selection of products, Get another Y selection for free”.

I wrote some quick and dirty codes to do “Buy X selection of products, Get another Y selection for free” quite a while ago, but this release refactors the codes into a standard standalone Magento extension.

How to install:
Copy the whole “app” folder, merge to magento/app. That’s it.

If you are logged in Magento backend when doing installation, that’s fine. But you have to log out and log in again to access Buy X Get Y configuration section in System Configuration.

How to use:
Log in Magento backend, go to Promotions -> Shopping Cart Price Rules, create a new rule whose name must start with “[bxgy]“;

In “Rule Information” tab, apart from the Rule Name, set up everything else as if it is normal Magento sales rule;

Screenshot: Rule Information

In “Conditions” tab, create a product total quantity subselect. The product subselect should match the selection of X product in the offer, and condition is “equals or greater than”, and quantity should match the quantity of X product used as qualifier;
* Do not create more than one subselect. Result is unpredictable otherwise.
* The condition must be “equals or greater than” and the quantity must be the threshold quantity of the offer. Although the calculation of the free quota of Y product is not dependent on the quantity (it is dependent on the settings in “Actions” tab), the offer validation is still Magento original logic. This module changes the discount amount after the offer validation. In other words, you must think about when to trigger Magento native “buy x get y”, and do the same conditions for this module.

Screenshot: Conditions

In “Actions” tab, set Apply to “Buy X get Y (discount amount is Y)” (although this is not normal buy_x_get_y action, the program still check this simple_action), set Discount amount to offer free quota, set Maximum Qty Discount is Applied to to 0, set Discount Qty Step (Buy X) to offer quantity qualifier. For example, if the offer is “buy any 3 of X products, and get any 2 of Y products free”, then set Discount amount to 3, set Maximum Qty Discount is Applied to to 0, set Discount Qty Step (Buy X) to 2. Then, in “Apply the rule only to cart items matching the following conditions (leave blank for all items)”, create a combination of conditions which match the selection of Y product in the offer. Multi combination is OK;

Screenshot: Actions

In “Label” tab, enter the offer labels as normal. It is not required, but if you leave it blank, the “ugly” Rule Name “[bxgy]***” will be used is discount description;

Now save the rule, and go to System -> Configuration -> Buy X Get Y -> Buy X selection of products, Get another Y selection for free, set up the offer reminder message in cart. It is not required. And if it is not set up, the offer is still taking effect as long as the sales rule is enabled.

How is it created:
This module is created by koukou1985’s module creator (http://www.magentocommerce.com/wiki/custom_module_with_custom_database_table). Thanks to koukou1985.

How good is it:
This module does not override any Mage classes. It is safe to use with other extensions as long as namespace and module name do not conflict.

FAQ:
Q: Why this module does not work?
A: I won’t cover all reasons that make my module not working. I only point out caveats of my module, and expect you to have common knowledge of Magento, such as “refresh the cache to see the newly installed features”. All caveats are in above sections. So, if you are stuck, go back to the top and read again.

Download BuyXGetY.tar.gz

今天我做了个有趣的实验：

1. 首先 Manage Attributes，设置某 product attribute ‘my_attr’ scope 为 Store view
2. 然后 Manage Products，为 my_attr 设置 default value ‘aaa’，再设置 store view (假设 storeId = 2) value ‘bbb’
3. 然后 Manage Attributes， 把 my_attr scope 改为 Global
4. 然后 Manage Products，Choose Store View (storeId = 2)，这时仍可见 my_attr 显示值 ‘bbb’。It means although my_attr scope is changed to ‘Global’, but old store view specific values are not removed.
5. 这时 (my_attr scope is Global) 如果在 Store View (storeId = 2) 状态把 my_attr 的值改为 ‘ccc’，then Save Product。my_attr default value 被改为 ‘ccc’，store view (storeId = 2) value 仍为 ‘bbb’。It means when my_attr scope is ‘Global’, it is not possible using Manage Products GUI to change or remove existing store view value.

摸清 Magento 的规律后就容易理解 Manage Products GUI 在 scope 改变或 store view 切换时的行为。另文有提及 change product default value and store view view by programming.

今天终于搞清楚了一件困扰我已久的问题：在 Magento Sales Module 下有两个分支 Mage_Sales_Model_Entity 和 class Mage_Sales_Model_Mysql4，看上去文件结构比较相似，Sales 和其他模块一时用 Mage_Sales_Model_Entity，一时又用 Mage_Sales_Model_Mysql4。它们有什么区别？为什么要同时存在？有必要同时存在吗？如要删除一个，该删哪个保留哪个？

以前有个任务，想要给 order 等 entity 添加一些自定义属性，因为搞不清楚哪个在起作用，我把两个类都 extends 了，即 class Mage_Sales_Model_Entity_Setup 和 class Mage_Sales_Model_Mysql4_Setup。而因为其他一些原因，自定义属性并不能完全按照我的意愿工作，所以我也没办法再用替换法去测试哪个类在起作用。

今天重新回顾了这个问题，摸清 Mage_Sales_Model_Entity is deprecated。When extending sales entity, only need to extend classes in Mage_Sales_Model_Mysql4.

但是简单地删除 magento/app/code/core/Mage/Sales/Model/Entity 目录则会导致程序找不到必要的文件而出错。我的建议是了解 Mage_Sales_Model_Entity is deprecated 这个事实就可以了，如果一定想割了这个阑尾目录，得做一些调整：

• 搜索一下哪些 class extends Entity 下的类 (search for Mage_Sales_Model_Entity under magento folder)，把它们改成 extends Mysql4 下对应的类。据我搜索结果，只有 Mage_Reports 一些 class extends Entity 下的类，或许 Mage_Sales 在 Mage_Reports 成形之后进行 Entity to Mysql4 的调整，而为了省事，保留 Entity 下的类，就不用去修改 Mage_Reports 了。
• 搜索一下哪些地方用到了 getModel(’sales_entity/entity_name’) 的方式，把它们改成 getModel(’sales_mysql4/entity_name’)。这需要同时搜索文件和数据库（数据库里 eav_attribute 有几个 backend models 是这样被引用的）。如果嫌这么替换比较麻烦，也可以修改 magento/app/code/core/Mage/Sales/etc/config.xml，把 <sales_entity><class>Mage_Sales_Model_Entity</class></sales_entity> 修改成 <sales_entity><class>Mage_Sales_Model_Mysql4</class></sales_entity>，这样就把 sales_entity model 与 sales_mysql4 model 等价起来了。