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extern crate env_logger;
extern crate handlebars;
#[macro_use]
extern crate serde_derive;
extern crate serde_json;
use serde_json::value::{Map, Value as Json};
use std::error::Error;
use handlebars::{
to_json, Context, Handlebars, Helper, JsonRender, Output, RenderContext, RenderError,
};
// define a custom helper
fn format_helper(
h: &Helper,
_: &Handlebars,
_: &Context,
_: &mut RenderContext,
out: &mut dyn Output,
) -> Result<(), RenderError> {
// get parameter from helper or throw an error
let param = h
.param(0)
.ok_or(RenderError::new("Param 0 is required for format helper."))?;
let rendered = format!("{} pts", param.value().render());
out.write(rendered.as_ref())?;
Ok(())
}
// another custom helper
fn rank_helper(
h: &Helper,
_: &Handlebars,
_: &Context,
_: &mut RenderContext,
out: &mut dyn Output,
) -> Result<(), RenderError> {
let rank = h
.param(0)
.and_then(|v| v.value().as_u64())
.ok_or(RenderError::new(
"Param 0 with u64 type is required for rank helper.",
))? as usize;
let total = h
.param(1)
.as_ref()
.and_then(|v| v.value().as_array())
.map(|arr| arr.len())
.ok_or(RenderError::new(
"Param 1 with array type is required for rank helper",
))?;
if rank == 0 {
out.write("champion")?;
} else if rank >= total - 2 {
out.write("relegation")?;
} else if rank <= 2 {
out.write("acl")?;
}
Ok(())
}
static TYPES: &'static str = "serde_json";
// define some data
#[derive(Serialize)]
pub struct Team {
name: String,
pts: u16,
}
// produce some data
pub fn make_data() -> Map<String, Json> {
let mut data = Map::new();
data.insert("year".to_string(), to_json("2015"));
let teams = vec![
Team {
name: "Jiangsu Suning".to_string(),
pts: 43u16,
},
Team {
name: "Shanghai SIPG".to_string(),
pts: 39u16,
},
Team {
name: "Hebei CFFC".to_string(),
pts: 27u16,
},
Team {
name: "Guangzhou Evergrand".to_string(),
pts: 22u16,
},
Team {
name: "Shandong Luneng".to_string(),
pts: 12u16,
},
Team {
name: "Beijing Guoan".to_string(),
pts: 7u16,
},
Team {
name: "Hangzhou Greentown".to_string(),
pts: 7u16,
},
Team {
name: "Shanghai Shenhua".to_string(),
pts: 4u16,
},
];
data.insert("teams".to_string(), to_json(&teams));
data.insert("engine".to_string(), to_json(TYPES));
data
}
fn main() -> Result<(), Box<dyn Error>> {
env_logger::init();
// create the handlebars registry
let mut handlebars = Handlebars::new();
// register template from a file and assign a name to it
handlebars.register_template_file("table", "./examples/render/template.hbs")?;
// register some custom helpers
handlebars.register_helper("format", Box::new(format_helper));
handlebars.register_helper("ranking_label", Box::new(rank_helper));
// make data and render it
let data = make_data();
println!("{}", handlebars.render("table", &data)?);
Ok(())
}
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