handlebars/helpers/
helper_lookup.rs

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1use serde_json::value::Value as Json;
2
3use crate::context::Context;
4use crate::error::RenderError;
5use crate::helpers::HelperDef;
6use crate::json::value::ScopedJson;
7use crate::registry::Registry;
8use crate::render::{Helper, RenderContext};
9use crate::RenderErrorReason;
10
11#[derive(Clone, Copy)]
12pub struct LookupHelper;
13
14impl HelperDef for LookupHelper {
15    fn call_inner<'reg: 'rc, 'rc>(
16        &self,
17        h: &Helper<'rc>,
18        r: &'reg Registry<'reg>,
19        _: &'rc Context,
20        _: &mut RenderContext<'reg, 'rc>,
21    ) -> Result<ScopedJson<'rc>, RenderError> {
22        let collection_value = h
23            .param(0)
24            .ok_or(RenderErrorReason::ParamNotFoundForIndex("lookup", 0))?;
25        let index = h
26            .param(1)
27            .ok_or(RenderErrorReason::ParamNotFoundForIndex("lookup", 1))?;
28
29        let value = match *collection_value.value() {
30            Json::Array(ref v) => index.value().as_u64().and_then(|u| v.get(u as usize)),
31            Json::Object(ref m) => index.value().as_str().and_then(|k| m.get(k)),
32            _ => None,
33        };
34        if r.strict_mode() && value.is_none() {
35            Err(RenderError::strict_error(None))
36        } else {
37            Ok(value.unwrap_or(&Json::Null).clone().into())
38        }
39    }
40}
41
42pub static LOOKUP_HELPER: LookupHelper = LookupHelper;
43
44#[cfg(test)]
45mod test {
46    use crate::registry::Registry;
47
48    #[test]
49    fn test_lookup() {
50        let mut handlebars = Registry::new();
51        assert!(handlebars
52            .register_template_string("t0", "{{#each v1}}{{lookup ../v2 @index}}{{/each}}")
53            .is_ok());
54        assert!(handlebars
55            .register_template_string("t1", "{{#each v1}}{{lookup ../v2 1}}{{/each}}")
56            .is_ok());
57        assert!(handlebars
58            .register_template_string("t2", "{{lookup kk \"a\"}}")
59            .is_ok());
60
61        let m = json!({"v1": [1,2,3], "v2": [9,8,7]});
62
63        let m2 = json!({
64            "kk": {"a": "world"}
65        });
66
67        let r0 = handlebars.render("t0", &m);
68        assert_eq!(r0.ok().unwrap(), "987".to_string());
69
70        let r1 = handlebars.render("t1", &m);
71        assert_eq!(r1.ok().unwrap(), "888".to_string());
72
73        let r2 = handlebars.render("t2", &m2);
74        assert_eq!(r2.ok().unwrap(), "world".to_string());
75
76        assert!(handlebars.render_template("{{lookup}}", &m).is_err());
77        assert!(handlebars.render_template("{{lookup v1}}", &m).is_err());
78        assert_eq!(
79            handlebars.render_template("{{lookup null 1}}", &m).unwrap(),
80            ""
81        );
82        assert_eq!(
83            handlebars.render_template("{{lookup v1 3}}", &m).unwrap(),
84            ""
85        );
86    }
87
88    #[test]
89    fn test_strict_lookup() {
90        let mut hbs = Registry::new();
91
92        assert_eq!(
93            hbs.render_template("{{lookup kk 1}}", &json!({"kk": []}))
94                .unwrap(),
95            ""
96        );
97        assert!(hbs
98            .render_template("{{lookup kk 0}}", &json!({ "kk": [null] }))
99            .is_ok());
100
101        hbs.set_strict_mode(true);
102
103        assert!(hbs
104            .render_template("{{lookup kk 1}}", &json!({"kk": []}))
105            .is_err());
106        assert!(hbs
107            .render_template("{{lookup kk 0}}", &json!({ "kk": [null] }))
108            .is_ok());
109    }
110}
handlebars/helpers/helper_lookup.rs

handlebars/helpers/
helper_lookup.rs
