Variable Filters

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By default, bindings are inserted into the output as-is; no consideration is given as to whether the target variable or file is XML, HTML, JSON etc. That is, the target file type is always treated as plain text.

Octopus variable substitutions support filters to correctly encode values for a variety of target file types. These are invoked using the | (pipe) operator.

Given the variable:

Name Value Scope
ProjectName You & I

An the template:

<h3>#{ProjectName | HtmlEscape}</h3>

The result will be:

<h3>You &amp; I</h3>

That is, the ampersand has been encoded correctly for use in an HTML document.

The filters provided by Octopus are for use with trusted input; don't rely on them to sanitize data from potentially malicious sources.

Provided Filters

Octopus provides the following filters:

Name Purpose Example Input Example Output
HtmlEscape Escapes entities for use in HTML content 1 < 2 1 &lt; 2
JsonEscape Escapes data for use in JSON strings He said "Hello!" He said \"Hello!\"
Markdown Converts Markdown to HTML This _rocks_ <p>This <em>rocks</em></p>
ToBase64 Converts values to Base64 (using UTF encoding) Bar QmF6
ToLower Forces values to lowercase Automated Deployment automated deployment
ToUpper Forces values to uppercase Automated Deployment AUTOMATED DEPLOYMENT
XmlEscape Escapes entities for use in XML content 1 < 2 1 &lt; 2

The NowDate and NowDateUtc filters take no variable input but can take an additional optional right-hand-side argument the define the string format (Defaults to ISO-8601 Round-trip format).

MyFormat Variable Filter Expression Output
#{ | NowDate } 2016-11-03T08:53:11.0946448
#{ | NowDateUtc} 2016-11-02T23:01:46.9441479Z
#{ | NowDate "HH dd-MMM-yyyy"} 09 03-Nov-2016
#{ | NowDateUtc zz} +00
dd-MM-yyyy #{ | NowDate #{MyFormat}} 03-Nov-2016

The Format filter introduced in Octopus 3.5 allows for converting of input based on an additionally provided argument that is passed to the .ToString() method.

MyVar Value Example Input Output
4.3 #{ MyVar | Format C} $4.30
2030/05/22 09:05:00 #{ MyVar | Format yyyy} 2030
#{ | NowDate | Format Date MMM} Nov

The Replace filter introduced in Octopus 2018.8.4 performs a regular expression replace function on the variable. The regular expression should be provided in the .NET Framework format. Double quotes need to be used around any expressions that contain whitespace or special characters. Expressions containing double quotes can not be expressed inline, but can be done via nested variables. If both the search and replace expressions are variables, ensure there is no space between the expressions.

MyVar Value Example Input Output
abc #{ MyVar | Replace b} ac
abc #{ MyVar | Replace b X} aXc
a b c #{ MyVar | Replace "a b" X} X c
ab12c3 #{ MyVar | Replace "[0-9]+" X} abXcX
abc #{ MyVar | Replace "(.)b(.)" "$2X$1" } cXa
abc #{ MyVar | Replace #{match}#{replace}} a_c when match=b,replace=_
abc #{ MyVar | Replace #{match} _} a_c when match=b

Filters were introduced in Octopus 3.5.

Differences From Regular Variable Bindings

Because of the flexibility provided by the extended syntax, variables that are not defined will result in the source text, e.g. #{UndefinedVar} being echoed rather than an empty string, so that evaluation problems are easier to spot and debug. The if construct can be used to selectively bind to a variable only when it is defined, e.g. to obtain identical "empty" variable functionality as shown in the first example:

Server=#{if DatabaseServer}#{DatabaseServer}#{/if};

JSON Parsing

Octostache 2.x (bundled with Octopus 3.5) includes an update to support parsing JSON formatted variables natively, and using their contained properties for variable substitution.

Given the variable:

Name Value Scope
Custom.MyJson {Name: "t-shirt", Description: "I am a shirt", Sizes: [{size: "small", price: 15.00}, {size: "large", price: 20.00}]}
Custom.MyJson.Description Shirts are not shorts.

And the template:

<h1>#{Custom.MyJson[Name]}</h1>
#{Custom.MyJson.Name} - #{Custom.MyJson.Description}
From: #{Custom.MyJson.Sizes[0].price | Format C}
Sizes: #{Custom.MyJson.Sizes}

The result will be:

<h1>t-shirt</h1>
t-shirt - Shirts are not shorts
From: $15.00
Sizes: [{size: "small", price: 15.00}, {size: "large", price: 20.00}]

There are a few things to note here:

  • The Name property is extracted from the JSON using either dot-notation or indexing.
  • Providing an explicit project variable overrides one obtained by walking through the JSON.
  • Arrays can be accessed using standard numerical index notation.
  • Variables can map to a sub-section of the JSON variable.

Repetition Over JSON

Give the variables:

Name Value
MyNumbers [5,2,4]
MyObjects {Cat: {Price: 11.5, Description: "Meow"}, Dog: {Price: 17.5, Description: "Woof"}}

And the template:

Numbers:
#{each number in MyNumbers}
 - #{number}
#{/each}

Objects:
#{each item in MyObjects}
	#{item.Key}: #{item.Value.Price}
#{/each} 

The resulting text will be:

Numbers:
 - 5
 - 2
 - 4
 
Objects:
Cat: 11.5
Dog: 17.5