Struct handlebars_concat::HandlebarsConcat

pub struct HandlebarsConcat;

Concat helper for handlebars-rust

Registration

use handlebars::Handlebars;
use handlebars_concat::HandlebarsConcat;
use serde_json::json;

let mut h = Handlebars::new();
h.register_helper("concat", Box::new(HandlebarsConcat));

assert_eq!(h.render_template(r#"{{concat item1 item2}}"#, &json!({"item1": "Value 1", "item2": "Value 2"})).expect("Render error"), "Value 1,Value 2");
assert_eq!(h.render_template(r#"{{concat this separator=", "}}"#, &json!({"item1": "Value 1", "item2": "Value 2"})).expect("Render error"), "item1, item2");
assert_eq!(h.render_template(r#"{{#concat this separator=", "}}{{this}}{{/concat}}"#, &json!({"item1": "Value 1", "item2": "Value 2"})).expect("Render error"), "Value 1, Value 2");
assert_eq!(h.render_template(r#"{{#concat "Form" this separator="" render_all=true}}<{{#if tag}}{{tag}}{{else}}{{this}}{{/if}}/>{{/concat}}"#, &json!({"key0":{"tag":"Input"},"key1":{"tag":"Select"},"key2":{"tag":"Button"}})).expect("Render error"), "<Form/><Input/><Select/><Button/>");

Behavior

The helper is looking for multiple arguments of type string, array or object. Arguments are being added to an output buffer and returned altogether as string.

The helper has few parameters modifying the behavior slightly. For example distinct=true eliminates duplicate values from the output buffer, while quotes=true in combination with single_quote=true wraps the values in quotation marks.

String

String arguments are added directly to the output buffer. As of 0.1.3 strings could be handled in one of two ways:

1. By default strings are added to the output buffer without modification (other than the quotation mark modifiers).
2. If you add a block template and use the render_all parameter, strings will be passed as {{this}} to the block template.

The block template rendering is disabled by default for backward compatibility.

Array

Array arguments are iterated and added as individual strings to the output buffer. As of 0.1.3 arrays could be handled in one of two ways:

1. By default array values are added as individual strings to the output buffer without modification (other than the quotation mark modifiers).
2. If you add a block template and use the render_all parameter, array values are passed as {{this}} to the block template.

The block template rendering is disabled by default for backward compatibility.

Object

Object arguments could be handled two different ways:

1. By default only the object keys are being used and the values are ignored.
2. If you add a block template the helper will use it to render the object value and concatenate it as string to the output buffer.

Object rendering results are subject to distinct, quotes and single_quote modifier parameters, just like strings and arrays.

Hash parameters

• separator: Set specific string to join elements with. Default is “,”
• distinct: Eliminate duplicates upon adding to output buffer
• quotes: Wrap each value in double quotation marks
• single_quote: Modifier of quotes to switch to single quotation mark instead
• render_all: Render all values using the block template, not just object values

Example usage:

Example with string literals:

{{concat "One" "Two" separator=", "}}

Result: One, Two

---

{{concat "One" "Two" separator=", " quotes=true}}

Result: "One", "Two"

---

Where s is "One", arr is ["One", "Two"] and obj is {"Three":3}

{{concat s arr obj separator=", " distinct=true}}

Result: One, Two, Three

---

Where s is "One", arr is ["One", "Two"] and obj is {"key0":{"label":"Two"},"key1":{"label":"Three"},"key2":{"label":"Four"}}:

{{#concat s arr obj separator=", " distinct=true}}{{label}}{{/concat}}

Result: One, Two, Three, Four

---

Where s is "One", arr is ["One", "Two"] and obj is {"key0":{"label":"Two"},"key1":{"label":"Three"},"key2":{"label":"Four"}}

{{#concat s arr obj separator=", " distinct=true render_all=true}}<{{#if label}}{{label}}{{else}}{{this}}{{/if}}/>{{/concat}}

Result: <One/>, <Two/>, <Three/>, <Four/>

---

Trait Implementations

impl Clone for HandlebarsConcat

fn clone(&self) -> HandlebarsConcat

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl HelperDef for HandlebarsConcat

fn call<'reg: 'rc, 'rc>( &self, h: &Helper<'rc>, r: &'reg Handlebars<'_>, ctx: &'rc Context, rc: &mut RenderContext<'reg, 'rc>, out: &mut dyn Output, ) -> HelperResult

A complex version of helper interface.

fn call_inner<'reg, 'rc>( &self, _: &Helper<'rc>, _: &'reg Registry<'reg>, _: &'rc Context, _: &mut RenderContext<'reg, 'rc>, ) -> Result<ScopedJson<'rc>, RenderError>

where 'reg: 'rc,

A simplified api to define helper

impl Copy for HandlebarsConcat