This document describes the syntax and semantics of the template engine and will be most useful as reference to those creating Jinja templates. As the template engine is very flexible, the configuration from the application can be slightly different from the code presented here in terms of delimiters and behavior of undefined values.
A Jinja template is simply a text file. The template syntax is heavily inspired by Django and Python. Below is a minimal template that illustrates a few basics using the default Jinja configuration.
We will cover the details later in this document:. The following example shows the default configuration settings. As stated above, any file can be loaded as a template, regardless of file extension. Adding a. Another good heuristic for identifying templates is that they are in a templates folder, regardless of extension. This is a common layout for projects.
You can mess around with the variables in templates provided they are passed in by the application. Variables may have attributes or elements on them you can access too. What attributes a variable has depends heavily on the application providing that variable. You can use a dot. If a variable or attribute does not exist, you will get back an undefined value. What you can do with that kind of value depends on the application configuration: the default behavior is to evaluate to an empty string if printed or iterated over, and to fail for every other operation.
For the sake of convenience, foo. This is important if an object has an item and attribute with the same name. Additionally, the attr filter only looks up attributes. Variables can be modified by filters. Filters are separated from the variable by a pipe symbol and may have optional arguments in parentheses. Multiple filters can be chained. The output of one filter is applied to the next. Filters that accept arguments have parentheses around the arguments, just like a function call.
The List of Builtin Filters below describes all the builtin filters. Tests can be used to test a variable against a common expression.
To test a variable or expression, you add is plus the name of the test after the variable.GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.
Already on GitHub? Sign in to your account. Backslash escaping logic appears to be wrong inside a Jinja template. Trying to use a string that ends with a backslash in a template may fail.Python and Jinja2 Cisco Network Automation
Background: I'm dealing with Windows hosts and in one of my playbook I want to concatenate some variables with a single backslash as part of a conditional statement in a Jinja template. I expect to have a proper way to include a string that ends with a backslash inside a Jinja template. I can't find such a way. If these files are inaccurate, please update the component name section of the description or use the!
Need to look into this further. Thanks sivelI completely missed that. I don't follow. This is not the bug so what does this prove? Skip to content. Dismiss Join GitHub today GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. Sign up. New issue. Jump to bottom. Copy link Quote reply. This comment has been minimized.
Sign in to view. Files identified in the description: None If these files are inaccurate, please update the component name section of the description or use the! I am also running into this issue, and I believe the bug report is right.Released: Feb 24, View statistics for this project via Libraries. Characters that have special meanings are replaced so that they display as the actual characters.
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Donate The Pallets organization develops and supports MarkupSafe and other libraries that use it. Release history Release notifications.This part of the documentation lists the filter- test- and helper functions you can use in templates.
In the examples above you might have noticed the pipe symbols. Pipe symbols tell the engine that it has to apply a filter on the variable.
Python Jinja tutorial
Here is a small example:. This will look for a variable variablepass it to the filter replace with the arguments 'foo' and 'bar'and pass the result to the filter escape that automatically XML-escapes the value. The e filter is an alias for escape. Here is the complete list of supported filters:. A filter that batches items. It works pretty much like slice just the other way round.
It returns a list of lists with the given number of items. If you provide a second parameter this is used to fill missing items. See this example:.
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Store the value in a variable called captured or a variable with the name provided. Useful for filter blocks:. This will output " One time from the filter block and one time from the variable. If you don't want the filter to output something you can use it in clean mode:.
If the value is undefined it will return the passed default value, otherwise the value of the variable:. If you want to use default with variables that evaluate to false you have to set the second parameter to true :. Sort a dict and yield key, value pairs.
Because python dicts are unsorted you may want to use this function to order them by either key or value:. Use dformat for that. Return a copy of the passed string, each line indented by 4 spaces.This page provides a basic overview of correct YAML syntax, which is how Ansible playbooks our configuration management language are expressed. Further, there are libraries available in most programming languages for working with YAML. You may also wish to read Working With Playbooks at the same time to see how this is used in practice.
So, we need to know how to write lists and dictionaries in YAML. All YAML files regardless of their association with Ansible or not can optionally begin with and end with This is part of the YAML format and indicates the start and end of a document. All members of a list are lines beginning at the same indentation level starting with a "- " a dash and a space :.
A dictionary is represented in a simple key: value form the colon must be followed by a space :. More complicated data structures are possible, such as lists of dictionaries, dictionaries whose values are lists or a mix of both:. In either case the indentation will be ignored. Examples are:. This really has nothing to do with Ansible, but will give you a feel for the format:. While you can put just about anything into an unquoted scalar, there are some exceptions.
A colon followed by a space or newline ": " is an indicator for a mapping. A space followed by the pound sign " " starts a comment. The difference between single quotes and double quotes is that in double quotes you can use escapes:.
If your value starts with a quote the entire value must be quoted, not just part of it. Here are some additional examples of how to properly quote things:. You should also be aware of? Boolean conversion is helpful, but this can be a problem when you want a literal yes or other boolean values as a string. In these cases just use quotes:. YAML converts certain strings into floating-point values, such as the string 1.
If you need to specify a version number in a requirements. Ansible 2.This document describes the API to Jinja2 and not the template language.
It will be most useful as reference to those implementing the template interface to the application and not those who are creating Jinja2 templates. Jinja2 uses a central object called the template Environment. Instances of this class are used to store the configuration, global objects and are used to load templates from the file system or other locations. Even if you are creating templates from string by using the constructor of Template class, an environment is created automatically for you, albeit a shared one.
Most applications will create one Environment object on application initialization and use that to load templates. The simplest way to configure Jinja2 to load templates for your application looks roughly like this:. This will create a template environment with the default settings and a loader that looks up the templates in the templates folder inside the yourapplication python package. Different loaders are available and you can also write your own if you want to load templates from a database or other resources.
To render it with some variables, just call the render method:. Using a template loader rather then passing strings to Template or Environment. Besides being a lot easier to use it also enables template inheritance.
Jinja2 is using unicode internally which means that you have to pass unicode objects to the render function or bytestrings that only consist of ASCII characters. Python 2. One is the str type and the other is the unicode type, both of which extend a type called basestring. Unfortunately the default is str which should not be used to store text based information unless only ASCII characters are used.
With Python 2. That way Python will store the string as unicode by decoding the string with the character encoding from the current Python module. To set a better module encoding add the following comment to the first or second line of the Python module using the unicode literal:. For Jinja2 the default encoding of templates is assumed to be utf It is not possible to use Jinja2 to process non unicode data. The reason for this is that Jinja2 uses Unicode already on the language level. For example Jinja2 treats the non-breaking space as valid whitespace inside expressions which requires knowledge of the encoding or operating on an unicode string.
For more details about unicode in Python have a look at the excellent Unicode documentation. Another important thing is how Jinja2 is handling string literals in templates.
The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. This is not coming from a template variable. Just plain html in my template. Learn more. Asked 5 years, 8 months ago. Active 5 years, 8 months ago. Viewed 19k times. Any help?
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