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Merge pull request #128 from holochain/2023-09-28-filter-helper
Implement `filter` helper and use it to suppress reactive variables for non-widget fields
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,157 @@ | ||
| use handlebars::{ | ||
| Context, Handlebars, Helper, HelperDef, RenderContext, RenderError, | ||
| ScopedJson, | ||
| }; | ||
| use serde_json::{json, Value, Map}; | ||
|
|
||
| #[derive(Clone, Copy)] | ||
| pub struct FilterHelper; | ||
|
|
||
| /// A Handlebars helper to filter an iterable JSON value. | ||
| /// It receives the value to be filtered and a string containing the condition predicate, | ||
| /// then uses Handlebars' truthy logic to filter the items in the value. | ||
| /// It also supports the `#if` helper's `includeZero` optional parameter. | ||
| impl HelperDef for FilterHelper { | ||
| fn call_inner<'reg: 'rc, 'rc>( | ||
| &self, | ||
| h: &Helper<'reg, 'rc>, | ||
| r: &'reg Handlebars<'reg>, | ||
| _ctx: &'rc Context, | ||
| _rc: &mut RenderContext<'reg, 'rc>, | ||
| ) -> Result<ScopedJson<'reg, 'rc>, RenderError> { | ||
| let mut params = h.params().iter(); | ||
| let value = params | ||
| .next() | ||
| .ok_or(RenderError::new( | ||
| "Filter helper: Param not found for index 0; must be value to be filtered", | ||
| ))? | ||
| .value(); | ||
|
|
||
| let condition = params | ||
| .next() | ||
| .ok_or(RenderError::new("Filter helper: Param not found for index 1; must be string containing filter condition predicate"))? | ||
| .value() | ||
| .as_str() | ||
| .ok_or(RenderError::new("Filter helper: filter condition predicate must be a string"))?; | ||
|
|
||
| let include_zero = h | ||
| .hash_get("includeZero") | ||
| .and_then(|v| v.value().as_bool()) | ||
| .unwrap_or(false); | ||
|
|
||
| // This template allows us to evaluate the condition according to | ||
| // Handlebars' available context/property logic, helper functions, and | ||
| // truthiness logic. | ||
| let template = format!( | ||
| "{}{}{}{}", | ||
| "{{#if ", | ||
| condition, | ||
| include_zero.then_some(" includeZero=true").unwrap_or(""), | ||
| "}}true{{else}}false{{/if}}" | ||
| ); | ||
|
|
||
| match value { | ||
| Value::Array(items) => { | ||
| let mut filtered_array = vec![]; | ||
| for item in items.iter() { | ||
| match r.render_template(&template, &item) { | ||
| Ok(s) => { | ||
| if s.as_str() == "true" { | ||
| filtered_array.push(item); | ||
| } | ||
| }, | ||
| Err(e) => { | ||
| return Err(e); | ||
| } | ||
| } | ||
| } | ||
| Ok(ScopedJson::Derived(json!(filtered_array))) | ||
| }, | ||
| Value::Object(object) => { | ||
| let mut filtered_object = Map::new(); | ||
| for key in object.clone().keys() { | ||
| if let Some(v) = object.get(key) { | ||
| match r.render_template(&template, &v) { | ||
| Ok(s) => { | ||
| if s.as_str() == "true" { | ||
| filtered_object.insert(key.into(), v.clone()); | ||
| } | ||
| }, | ||
| Err(e) => { | ||
| return Err(e); | ||
| } | ||
| } | ||
| } | ||
| } | ||
| Ok(ScopedJson::Derived(json!(filtered_object))) | ||
| }, | ||
| _ => Err(RenderError::new("Filter helper: value to be filtered must be an array or object")) | ||
| } | ||
| } | ||
| } | ||
|
|
||
| pub fn register_filter<'a>(mut h: Handlebars<'a>) -> Handlebars<'a> { | ||
| h.register_helper("filter", Box::new(FilterHelper)); | ||
|
|
||
| h | ||
| } | ||
|
|
||
| #[cfg(test)] | ||
| mod tests { | ||
| use handlebars::Handlebars; | ||
| use serde_json::json; | ||
| use crate::templates::helpers::register_filter; | ||
|
|
||
| fn setup_handlebars<'a>() -> Handlebars<'a> { | ||
| let hbs = Handlebars::new(); | ||
| let hbs = register_filter(hbs); | ||
| hbs | ||
| } | ||
|
|
||
| #[test] | ||
| fn respects_include_zero() { | ||
| let hbs = setup_handlebars(); | ||
| let value = json!([0, 1, 0, 2, 0, 3, 0, 4, 0, 5]); | ||
| // The predicate filters out zeroes. | ||
| let template = "{{#each (filter this \"this\")}}{{this}}{{/each}}"; | ||
| match hbs.render_template(&template, &value) { | ||
| Ok(s) => assert_eq!(s, "12345", "`filter` helper did not filter out falsy zero"), | ||
| Err(e) => panic!("{}", e) | ||
| } | ||
| // This predicate, however, does not. | ||
| let template = "{{#each (filter this \"this\" includeZero=true)}}{{this}}{{/each}}"; | ||
| match hbs.render_template(&template, &value) { | ||
| Ok(s) => assert_eq!(s, "0102030405", "`filter` helper did not treat zero as truthy"), | ||
| Err(e) => panic!("{}", e) | ||
| } | ||
| } | ||
|
|
||
| #[test] | ||
| fn can_filter_object_by_value() { | ||
| let hbs = setup_handlebars(); | ||
| let value = json!({"name": "Alice", "age": 24, "wild": false, "species": "iguana"}); | ||
| // The predicate filters out the 'wild' property. | ||
| let template = "{{#each (filter this \"this\")}}{{@key}}: {{this}}, {{/each}}"; | ||
| match hbs.render_template(&template, &value) { | ||
| Ok(s) => assert_eq!(s, "name: Alice, age: 24, species: iguana, ", "`filter` helper did not filter object key/value pairs by value"), | ||
| Err(e) => panic!("{}", e) | ||
| } | ||
| } | ||
|
|
||
|
|
||
| #[test] | ||
| fn can_filter_complex_value() { | ||
| let hbs = setup_handlebars(); | ||
| let value = json!([ | ||
| {"name": "Alice", "age": 24, "wild": true, "species": "iguana"}, | ||
| {"name": "Bob", "age": 3, "wild": false, "species": "hamster"}, | ||
| {"name": "Carol", "age": 1, "wild": true, "species": "octopus"} | ||
| ]); | ||
| // The predicate filters out domestic animals. | ||
| let template = "{{#each (filter this \"wild\")}}{{name}} the {{species}} is {{age}}. {{/each}}"; | ||
| match hbs.render_template(&template, &value) { | ||
| Ok(s) => assert_eq!(s, "Alice the iguana is 24. Carol the octopus is 1. ", "`filter` helper did not operate on a list full of complex values"), | ||
| Err(e) => panic!("{}", e) | ||
| } | ||
| } | ||
| } |
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