This article will help you understanding about loops and branching syntax of Blogger XML template code. If you are a template developer, you must read this.
Loops
You can use b:loops to scan all element in an array. The syntax will be:
<b:loop values='data:name_of_array' var='name_of_element'> <data:name_of_element/> <data:name_of_element.name_of_property/> </b:loop>
name_of_array is the name of an array variable. You CAN NOT input any name here, you must follow the real names in Blogger variable list.
name_of_element you CAN input any name here. If element is a string or number, you can output it directly by using
<data:name_of_key/>
. If it’s an object, you can use <data:name_of_key.name_of_property/>
to access its properties. name_of_property must follow the real name in Blogger variable list.
Example with the loop inside Profile widget
<b:loop values='data:authors' var='i'> <li> <a class='profile-name-link g-profile' expr:href='data:i.userUrl' expr:style='"background-image: url(" + data:i.profileLogo + ");"'> <data:i.display-name/> </a> </li> </b:loop>
Branching
You can use b:if for branching your code. The full syntax will be:
<b:if cond='your_condition_expression'> <!-- Do something if the condition is true --> <b:elseif cond='another_condition_expression'/> <!-- Do something if another condition is true --> <b:else/> <!-- Do something if all conditions are false --> </b:if>
The condition expression is ==, !=, >=, <= (Blogger did not allow you input >= or <= so you must use >= and <=). Example:
<b:if cond='data:blog.pageType == "index"'> This is INDEX PAGE </b:if> <b:if cond='false'> This is the LEGEND if (0) </b:if>
You can also combine more than one condition using && and || (Blogger not allow you input &&, so you must use &&)
<b:if cond='data:blog.pageType == "item" && data:blog.postImageUrl'> This is COOL </b:if>
Blogger also supported express branching conditions. The syntax is:
your_condition_expression? action_when_true : action_when_false
Here is an example for printing viewport meta data in template header
<meta expr:content='data:blog.isMobile ? "width=device-width,initial-scale=1.0,minimum-scale=1.0,maximum-scale=1.0" : "width=1100"' name='viewport'/>
Update
Previously, the expressions in Blogger’s templates could
Add or concatenate values with +
Subtract values with –
Check for equality with != and ==
Compare values with <, >, <= and >=Now, support has been added for many more expression operators, including:
Add or concatenate values with +
Subtract values with –
Check for equality with != and ==
Compare values with <, >, <= and >=Now, support has been added for many more expression operators, including:
- Inversion of true/false values with !/not e.g. <b:if cond=‘!data:post.allowComments’>…
- Picking between 2 values with ?: e.g. <a expr:class=‘data:post.allowComments ? “comments” : “no-comments”‘ …
- Checking if a value is a member of a set or array, with in/contains e.g. <b:ifcond=‘data:blog.pageType in {“index”, “archive”}’>…
- Combining multiple conditions with and/or e.g. <b:if cond=‘data:blog.pageType == “index” and data:post.allowComments’>…
- Changing the order of operations with () e.g. <div expr:style=‘”max-width: ” + (data:width + 10) + “px;”‘>…