1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
|
# Askama
[](https://crates.io/crates/askama)
[](https://travis-ci.org/djc/askama)
[](https://codecov.io/gh/djc/askama)
Askama implements a template rendering engine based on Jinja.
It generates Rust code from your templates at compile time
based on a user-defined `struct` to hold the template's context.
See below for an example, or read [the documentation][docs].
**"Pretty exciting. I would love to use this already."** --
[Armin Ronacher][mitsuhiko], creator of Jinja
All feedback welcome. Feel free to file bugs, requests for documentation and
any other feedback to the [issue tracker][issues] or [tweet me][twitter].
Many thanks to [David Tolnay][dtolnay] for his support in improving Askama.
### Feature highlights
* Construct templates using a familiar, easy-to-use syntax
* Benefit from the safety provided by Rust's type system
* Template code is compiled into your crate for optimal performance
* Templates only convert your data as needed
* Templates can access your Rust types directly, according to Rust's
privacy rules
* Debugging features to assist you in template development
* Templates must be valid UTF-8 and produce UTF-8 when rendered
* Works on stable Rust
### Supported in templates
* Template inheritance (one level only)
* Basic loops and if/else statements
* Whitespace suppressing with '-' markers
* Some built-in filters
### Limitations
* Still in beta -- not very mature yet
* Only a small number of built-in template filters have been implemented
* User-defined template filters are not supported yet
* Debugging template problems can be tricky
[docs]: https://docs.rs/askama
[mitsuhiko]: http://lucumr.pocoo.org/
[issues]: https://github.com/djc/askama/issues
[twitter]: https://twitter.com/djco/
[dtolnay]: https://github.com/dtolnay
How to get started
------------------
First, add the following to your crate's `Cargo.toml`:
```toml
# in section [package]
build = "build.rs"
# in section [dependencies]
askama = "0.3"
# in section [build-dependencies]
askama = "0.3"
```
Because Askama will generate Rust code from your template files,
the crate will need to be recompiled when your templates change.
This is supported by adding a build script, `build.rs`, to your crate.
It needs askama as a build dependency:
```rust
extern crate askama;
fn main() {
askama::rerun_if_templates_changed();
}
```
Now create a directory called `templates` in your crate root.
In it, create a file called `hello.html`, containing the following:
```
Hello, {{ name }}!
```
In any Rust file inside your crate, add the following:
```rust
#[macro_use]
extern crate askama; // for the Template trait and custom derive macro
use askama::Template; // bring trait in scope
#[derive(Template)] // this will generate the code...
#[template(path = "hello.html")] // using the template in this path, relative
// to the templates dir in the crate root
struct HelloTemplate<'a> { // the name of the struct can be anything
name: &'a str, // the field name should match the variable name
// in your template
}
fn main() {
let hello = HelloTemplate { name: "world" }; // instantiate your struct
println!("{}", hello.render()); // then render it.
}
```
You should now be able to compile and run this code.
Review the [test cases] for more examples.
[test cases]: https://github.com/djc/askama/tree/master/testing
Debugging and troubleshooting
-----------------------------
You can view the parse tree for a template as well as the generated code by
changing the `template` attribute item list for the template struct:
```rust
#[derive(Template)]
#[template(path = "hello.html", print = "all")]
struct HelloTemplate<'a> { ... }
```
The `print` key can take one of four values:
* `none` (the default value)
* `ast` (print the parse tree)
* `code` (print the generated code)
* `all` (print both parse tree and code)
The parse tree looks like this for the example template:
```
[Lit("", "Hello,", " "), Expr(WS(false, false), Var("name")),
Lit("", "!", "\n")]
```
The generated code looks like this:
```rust
#[allow(dead_code, non_camel_case_types)]
impl<'a> askama::Template for HelloTemplate<'a> {
fn render_to(&self, writer: &mut std::fmt::Write) {
writer.write_str("Hello,").unwrap();
writer.write_str(" ").unwrap();
writer.write_fmt(format_args!("{}", self.name)).unwrap();
writer.write_str("!").unwrap();
writer.write_str("\n").unwrap();
}
}
```
|
