芳草苑

Author: 芳草苑主

  • How to override a Magento controller

    Say I want to override Magento Catalog Product controller, say my namespace is Magex and my module name is Powercat.

    Firstly, add the following to Powercat/etc/config.xml. What it does is adding another route “prowercat” in addition to “catalog” to frontend. When http://mydomain/catalog/somecontroller/someaction/ is routered, powercat/somecontroller/someaction will be loaded before (see the attribute “before”?) catalog/somecontroller/someaction. If powercat/somecontroller/someaction is available, people get some page when visiting http://mydomain/catalog/somecontroller/someaction/ or http://mydomain/powercat/somecontroller/someaction/. I will not publish the latter url because the whole point of overriding a controller is reusing the Magento original url.

    <?xml version="1.0"?>
<config>
<frontend>
<routers>
<catalog>
<args>
<modules>
<anyname before="Mage_Catalog">Magex_Powercat</anyname><!-- the tag name can be any name -->
</modules>
</args>
</catalog>
</frontend>
</config>

    Secondly, create a subclass in the following format. “require_once” is essential because controllers are not auto-loaded.

    <?php
require_once 'Mage/Catalog/controllers/SomeController.php';
class Magex_Powercat_SomeController extends Mage_Catalog_SomeController
{
//function someAction here
}
?>

    Last but not the least, put the overriding controllers into a dedicated module. Otherwise it is very easy to break Magento fallback mechanism. For example, suppose Magex_Powercat has two controllers.

    1. Magex_Powercat_IndexController does its own logic (not extending Mage_Catalog_IndexController, and
    2. Magex_Powercat_ProductController extends Mage_Catalog_ProductController

    The scenarios are:

    • When people visit http://mydomain/catalog/product/someaction/, powercat/somecontroller/someaction will be loaded – OK.
    • When people visit http://mydomain/catalog/category/someaction/, catalog/category/someaction will be loaded (because Powercat does not have CategoryController, Magento will fallback to Mage’s CategoryController) – OK.
    • When people visit http://mydomain/catalog/index/someaction/, if Powercat’s IndexController does not have someAction (only Mage’s IndexController has) – Error happens!
    • When people visit http://mydomain/catalog/index/someaction/, if Powercat’s IndexController does have someAction, page will load without error. However, remember Magex_Powercat_IndexController does its own logic? No router to the original logic!

  • Magent Events

    Magento wiki 上有篇文章列出了所有的 events dispatched by Magento。但 wiki as a CMS 自作主张地转化了某些字符，比如把

    ->转化成了→

    =>转化成了⇒

    这让我觉得有必要自己来格式化这篇文档。虽然曾想用 OpenOffice 来存储，但它竟然连一张简单的表格都格式得很费劲，最后只好用了 Ms Word。

    Download magento-events

  • Mysql varchar could be transformed to memo in Ms Access

    Mysql varchar could be transformed to memo in Ms Access when Mysql table is used as linked table inside Access, but I want to prevent this from happening. Mainly because I can not join tables with memo field.

    As I observed, long Mysql varchar field is transformed to memo field, but short one stays as text field. The maximum length of varchar is 85 which allows varchar stays as text field in Access.

    This limitation is quite touch, isn’t it?

  • Geo Adwords

    众所周知，Google Adwords 可以根据访问者的地理位置选择性地投递广告。几番实验后，我发现其中的选择性非常微妙：

    我帮朋友的外卖店 Oriental Takeaway 开启了 Google Adwords 账户。非常遗憾地，朋友和我都没有很多时间去 refine adwords settings，仅做了一些非常基本的选择性投递，其中一项就是“仅限 Brighton 地区”。A primary keyword to target is brighton chinese takeaway (btw, we decided to use it as domain), together with other hundreds of keywords.

    我选择了三个地点测试，Brighton, Worthing, and some place in Germany。

    • 在 Brighton google，所有在 keyword list 上的广告都能出线，按下不表。
    • 在 Worthing google，搜索 brighton chinese takeaway，广告竟然也能出线。我很惊讶，一开始以为 Google 使用的 geo 数据不够精确，导致广告误投递。再搜索 brighton takeaway，广告也能出线；再搜索 chinese takeaway，广告不出线。
    • 在 Germany google，搜索 brighton takeaway，广告也能出线；再搜索 brighton takeaway，广告不出线；再搜索 chinese takeaway，广告不出线。

    由此我得出结论，广告是否出线跟 Adwords 的地域设置、地域距离以及关键词与网站的关联性多因素决定。

    总的来说，Google 非常聪明，我非常喜欢。

  • Understand how tax is calculated in Magento

    彻底理解 Magento tax 是如何计算的不是一件容易的事。我做了无数次组合测试，算是了解 Magento tax 是如何计算的，但我未及去读代码，不敢说彻底摸透它的来龙去脉，写下这段文字权作日后参考。

    首先，零税率不用设置，因为如果什么设置都没有的话税率就是零，所以大多数时候只要针对非零税率进行设置。稍后会讲到什么时候需要进行零税率设置。

    其次，要分清以下名词：

    • tax rate 税率
    • tax zone 税区域
    • tax rule 税规则
    • customer tax class 顾客税种
    • product tax class 产品税种
    • shipping tax class 运费税种
    • customer group 顾客属组
    • customer address 顾客地址

    它们的关系是：

    1. 税计算的起点是税规则。换言之，如果后台设置了若干税率、税区域、顾客税种、产品税种、运费税种，却没有设置税规则，那么没有任何税生效。
    2. 只有税规则可以设置优先级，税区域无法设置优先级（除非去改数据库，id 越小的税区域优先）。
    3. 税规则是产品税种（或运费税种）、顾客税种、税区域在三维空间决定的。
    4. 后台界面设置税率和税区域在一个表单里，似乎税率由税区域直接决定，但并不一定能生效，原因见第3点。
    5. 税区域与顾客税种无关。这点曾是我困惑的地方，因为地址是顾客的一个属性，所以我很自然地认为顾客地址就对应税区域。如果尝试着放弃“顾客地址就对应税区域”思维，一切都容易理解了。
    6. 税规则的三维空间较难描述，可以这么来简化：先拿产品税种（或运费税种）和顾客税种交叉排列组合出多个税规则，再拿税区域去套，套中的税规则就生效，套不中就不生效。
    7. 顾客属组和顾客税种是多对一的关系。
    8. 在前台 checkout 时，Magento 会根据顾客地址启用一条或多条税规则，但后台 create order 时，Magento 的税规则却无视顾客地址。这或许是 Magento 的一个 bug。

    我以一个实例说明如何在 Magento 中设置 UK VAT。以我目前所知，within the UK, postcode JE 和 GY9 开头的区域可以免 VAT，其他区域需加收 VAT，英国以外免 VAT。因为我没有免 VAT 区域的完整列表，必须照顾到今后能随时添加更多的 postcode 进免 VAT 区域。我是这么设置的：

    • 因为产品比较单一，运费税率与产品税率相同，目前都是17.5%，所以只设一个产品税种，不搞运费税种，运费就沿用产品税种，便于理解。
    • 顾客税种分两种，普通和VAT FREE。顾客属组也分两种，普通和VAT FREE，一一对应便于理解。请注意，普通类不是指一定要收 VAT，而是按税规则的第三维——税区域智能决定税率；但免 VAT 类下的顾客一定是零税率，这么做是为了照顾后台 create order 时的 bug（姑且当是）。
    • 建若干个税区域， UK postcode JE* 税率为0、UK postcode GY9* 税率为0、UK postcode * 税率为17.%。其他国家的税率不需要一个建，因为没有税规则，那就是零税率。

    现在开始创建税规则，按优先级别排序：

    1. 产品税种全选（反正只有一个），顾客税种选普通，税区域选 UK postcode JE*和UK postcode GY9*
    2. 产品税种全选（反正只有一个），顾客税种选普通，税区域选 UK postcode *
    3. 产品税种全选（反正只有一个），顾客税种选VAT FREE，税区域选 UK postcode JE*

    前两条规则是为了前台 checkout，第三条税规则是为了照顾后台 create order 时的 bug。Magento 目前版本 1.4.0.1，后台 create order 若把顾客归类普通，bug 无视税区域的存在，也不管税规则的优先级，似乎只会挑一个最高税率。普通顾客税种有0和17.5%两种可能，后台却总是用17.5%去收税。为避免激发 bug，干脆，顾客税种选VAT FREE，VAT FREE税种只有一个可能，永远是0，只在后台使用。

    如果今后得知 UK postcode XYZ* 也免 VAT，那就再建一个税区域 UK postcode XYZ* 税率为0；然后进入已有的税规则1，税区域增选 UK postcode XYZ* 即可。虽然税区域 UK postcode * 创建在先，UK postcode XYZ* 创建在后，但税规则的优先级别保证了 UK postcode XYZ* 先于 UK postcode *。

    再说一个极端的例子，若 UK 免 VAT 的区域只有 JE* 和 GY9*，今后也不会增加了，那么先创建税区域 UK postcode JE*和UK postcode GY9*，后创建 UK postcode *，然后只需要第1条税规则里同时选中UK postcode JE*、UK postcode GY9* 和 UK postcode *，删除税规则2也可以保证 UK postcode JE*和UK postcode GY9* 的优先性。但这么做有悖 Magento tax 的设计思路，不可取。

  • Nginx try_files syntax

    今天在一台很久不用的服务器上测试 Magento search result page，URL /catalogsearch/result/?q=searchword，发现它不工作，但其他页面正常。这个症状让我联想到以前碰到的类似问题，Magento 无法获得 query_string，所以含问号的 URL 都不能处理，页面重定向到 referring URL。应该是 server rewrite 规则没有写正确，我想。打开 nginx 的配置文件一看，果然，当中一条规则用的是很久以前的写法，后来在不同的服务器上几经改进，production server 都已经用上了新规则。

    新规则的写法：


    location @magento {
    root $php_script_root;
    index index.php;
    if ($uri ~ ^/(media|js|skin)/) {
    break;
    }
    if (!-e $request_filename) {
    rewrite .* /index.php last;
    }
    }

    而老规则的写法：


    location @magento {
    root $php_script_root;
    index index.php;
    if ($uri ~ ^/(media|js|skin)/) {
    break;
    }
    try_files $uri $uri/ /index.php;
    }

    效果略有区别，我在 Difference of try_files to rewrite in Nginx 文章里有提及。不过，今天我还有一个新发现。

    我倾向于使用简介语法，try_files 就比 rewrite 简洁得多，难道 try_files 就没有办法应付带问号的 URL 吗？非也，是我不知道 Nginx 原本可以这么奥妙——用 $args 变量！

    因此，最新一条完美规则出炉了：


    location @magento {
    root $php_script_root;
    index index.php;
    if ($uri ~ ^/(media|js|skin)/) {
    break;
    }
    try_files $uri $uri/ /index.php?$args;
    }

  • Style Magento checkout form fields without touching the core code

    Although I can change css complete restyle the checkout forms, this is not what I want to discuss today. What I want to achieve are:

    1. fix City required asterisk not showing bug
    2. change Address lines from full width to half width as City

    The City required asterisk is hidden by a javascript wrongly. I found City and State/County/Province are put into one li, i.e. <li><div></div></li>. It might be something should happen on State/County/Province but happens on City. If I close li after City, and reopen it before State/County/Province, bug is fixed. By the way, I hide State/County/Province.

    To show a field in full length, Magento uses
    <li><label><span></span></label><input/></li>
    To show a field in half length, Magento uses
    <li><div><label><span></span></label><input/></div></li>

    So just find the right place to insert <div> and close it for Address lines, I easily style them to the same length of City.

  • Magento idea: business intelligence

    It is very time consuming to set Related Products, Cross Sells, Up Sells on individual product basis, and not accurate if you work them out just using your brain. It is good to see Magento has these marketing terms built in, but I hate to do the job by hand (or brain).

    So I am thinking of developing a business intelligence module for Magento to let computer work Related Products, Cross Sells, Up Sells for us.

    Here is the overview of this module:

    First, we need record more data than what Magento provides. we specify a period of data to data-mine.

    Then, for Related Products, mine product pageviews by each visit. Put a visitor’s all visited products into an array, and count all visitors’ arrays for every product-product combination.

    As for Cross Sells, mine orders received or fulfilled. The algorithm is similar to Related Products.

    As for Up Sells, mine the products were added to cart but dropped from final order. Compare the product dropped with the products in final order, and if the former is of higher value, and some sort related to the latter, we can call the former Up Sells. This is my definition, and the algorithm is some sort complicated.

  • Chrome for Linux

    今天无意中发现 Google 有了 Linux 版的 Chrome，赶紧下载来装。以前也有 Linux 版的 Chrome，但要自己编译，我吃不消，盼望给我一个 rpm 很久。我在 Fedora 本来只有 Firefox 可用，偶尔用一下 Konqueror，但不顺手，所以 Firefox 挺寂寞的。

    Google 是开源先锋，我认为早就可以出 Linux 版的 Chrome 了，可是还是先出了 Windows 版的，到底还是 Windows 用户多嘛，用户至上，无可厚非。

  • Extend Magento inventory management

    Magento inventory management is very basic – only an Inventory Qty figure. Strictly speaking, it is not an “in-stock” figure, but an “orderable”. Because orders keep coming in but you only do despatch once a day, Magento inventory quantity changes upon order is placed online, so you can not tell how many pieces of a product sitting in the warehouse.

    Use only one figure to manage inventory is not enough. Imagine this scenario:
    You are doing stocktake someday. At the time of last despatch, Magento inventory quantity of product X is 100. Stocktaking takes many hours, and when it finishes, Magento inventory quantity has changed to 80. If you physically count product X as 95, you can not simply update Magento inventory figure to be 95. Instead you should change it to 75 (worked out as 80 – 100 + 95). It is very easy to make such mistakes in stocktaking, but I have only Magento to blame – if stocktaking is based on a figure which is changing from time to time, it is not rock solid.

    However, I am not thinking of introducing a 3rd party inventory management system to work with Magento, largely because I do not know which one can fit.

    I am thinking of a simple extension to Magento – use 3 figures to show stock level from different concerts. Let’s clarify the terminology first.
    Figure 1: inventory orderable, i.e. the existing Magento Inventory Qty;
    Figure 2: inventory in-stock, i.e. how many pieces in the warehouse;
    Figure 3: inventory coming, i.e. expected purchase.

    • When an order is placed, decrease inventory orderable
    • When an order is despatched, decrease inventory in-stock
    • When an order is cancelled before despatch, increase inventory orderable
    • When an order is cancelled after despatch, do nothing (some companies raise RMA at this point but we do not need it.)
    • When an order is returned, if goods in good condition, increase inventory orderable, and increase inventory in-stock
    • When a purchase order is placed (by us to our supplier), increase inventory coming
    • When a purchase order arrives, decrease inventory coming, increase inventory orderable, and increase inventory in-stock
    • When stocktake begins, snapshot inventory in-stock as inventory1
    • When stocktake ends, update inventory in-stock to inventory2, and add (inventory2 – inventory1) to inventory orderable

    If all above events are logged, we have a kind of traceability. The log gives some clue to analyse where “inventory2 – inventory1” is from.

    In case a customer asks “how many you have? I take them all”, we tell him/her inventory orderable.

    In case we need find out “how many on hold (for late despatch)”, we use the balance between inventory orderable and inventory in-stock.

    Inventory orderable (figure 1) is built-in with Magento. Inventory coming (figure 3) is not essential to stock control. We can introduce it after we have implemented inventory in-stock (figure 2).