Handle env files from stdin

Cargo.toml

@@ -15,6 +15,7 @@ env_logger = []
 [dependencies]
 clap = { version = "4", features = ["derive", "env", "unicode", "cargo"] }
 color-eyre = "0.6"
+dotenvy = "0.15.7"
 env_logger = "0.11"
 fluent-templates = { version = "0.9", optional = true, default-features = false, features = ["tera", "use-ignore"] }
 log = "0.4"

README.md

@@ -193,7 +193,7 @@ Passing the `-a | --escape` flag allows escaping the content.
     Usage: tera [OPTIONS] --template <TEMPLATE> [CONTEXT]
 
     Arguments:
-      [CONTEXT]  Location of the context data. This file can be of the following type: json | toml | yaml. If you prefer to pass the data as stdin, use `--stdin`
+      [CONTEXT]  Location of the context data. This file can be of the following type: json | toml | yaml. If you prefer to pass the data as stdin, use `--stdin`. On stdin, .env files are also supported.
 
     Options:
       -t, --template <TEMPLATE>          Location of the template

data/env-file/.env.file

@@ -0,0 +1,3 @@
+LOGNAME=chevdor
+HOME=/home/foobarqux
+EDITOR=emacs?

data/env-file/env-file.tera

@@ -0,0 +1,15 @@
+# ENV Demo
+
+{% if LOGNAME %}
+Hello **{{ LOGNAME }}**.
+{% endif %}
+
+This demo shows how your ENV variables can be used in a template.
+
+- Home: {% set fragments = HOME | split(pat="/") %}
+{%- for fragment in fragments -%}
+  {%- if fragment -%}
+    /{{ fragment }}
+  {%- endif %}
+{%- endfor %}
+- Editor: {{ EDITOR }}

doc/usage.adoc

@@ -3,7 +3,7 @@ Command line utility for the tera templating engine. You need to provide a templ
 Usage: tera [OPTIONS] --template <TEMPLATE> [CONTEXT]
 
 Arguments:
-  [CONTEXT]  Location of the context data. This file can be of the following type: json | toml | yaml. If you prefer to pass the data as stdin, use `--stdin`
+  [CONTEXT]  Location of the context data. This file can be of the following type: json | toml | yaml. If you prefer to pass the data as stdin, use `--stdin`. On stdin, .env files are also supported.
 
 Options:
   -t, --template <TEMPLATE>          Location of the template

src/opts.rs

@@ -30,7 +30,8 @@ pub struct Opts {
 	pub locales_path: Option<PathBuf>,
 
 	/// Location of the context data. This file can be of the following type:
-	/// json | toml | yaml. If you prefer to pass the data as stdin, use `--stdin`
+	/// json | toml | yaml. If you prefer to pass the data as stdin, use `--stdin`.
+	/// On stdin, .env files are also supported.
 	#[clap(index = 1, required_unless_present_any = &["stdin", "env_only"], conflicts_with = "env_only")]
 	pub context: Option<PathBuf>,
 

src/wrapped_context.rs

@@ -25,6 +25,7 @@ pub enum SupportedType {
 	Json,
 	Toml,
 	Yaml,
+	Env,
 }
 
 impl WrappedContext {
@@ -73,6 +74,17 @@ impl WrappedContext {
 		Ok(())
 	}
 
+	pub fn append_env_file(&mut self, str: &str) -> Result<()> {
+    debug!("Appending env file");
+    let env_cursor = std::io::Cursor::new(str);
+    for item in dotenvy::from_read_iter(env_cursor) {
+        let (k, v) = item.context("Failed to parse .env file line")?;
+        self.handle_collision("env", &k, &v);
+    }
+
+    Ok(())
+	}
+
 	fn handle_collision<K, V>(&mut self, from: &str, k: K, v: V)
 	where
 		K: Debug + AsRef<str>,
@@ -138,6 +150,13 @@ impl WrappedContext {
 			debug!("not yaml");
 		}
 
+    let env_cursor = std::io::Cursor::new(str);  // Create a reader from the string
+    if dotenvy::from_read_iter(env_cursor).all(|item| item.is_ok()) {
+        return Some(SupportedType::Env);
+    } else {
+        debug!("not env");
+    }
+
 		None
 	}
 
@@ -158,12 +177,13 @@ impl WrappedContext {
 				Some(SupportedType::Json) if !input.is_empty() => self.append_json(&input),
 				Some(SupportedType::Toml) if !input.is_empty() => self.append_toml(&input),
 				Some(SupportedType::Yaml) if !input.is_empty() => self.append_yaml(&input),
+				Some(SupportedType::Env) if !input.is_empty() => self.append_env_file(&input),
 				_ => Ok(()),
 			}
 			.context("failed to append stdin to context")?;
 		} else if let Some(context_file) = &self.opts.context {
 			let input = fs::read_to_string(context_file).context("failed to read context file")?;
-
+			
 			match context_file.extension() {
 				Some(ext) if ext == "json" => self.append_json(&input),
 				Some(ext) if ext == "toml" => self.append_toml(&input),

tests/test.rs

@@ -98,6 +98,19 @@ mod cli_tests {
 			let assert = cmd.write_stdin(stdin).arg("-t").arg("data/basic/basic.tera").arg("--stdin").assert();
 			assert.success().stdout(predicate::str::contains("Bob likes orange"));
 		}
+
+		#[test]
+		fn it_process_env_stdin() {
+			let mut cmd = Command::cargo_bin("tera").unwrap();
+			let stdin = fs::read_to_string("data/env-file/.env.file").unwrap();
+
+			let assert = cmd.write_stdin(stdin).arg("-t").arg("data/env-file/env-file.tera").arg("--stdin").assert();
+
+			assert.success().stdout(
+				predicate::str::contains("Hello **chevdor**")
+				.and(predicate::str::contains("Home: /home/foobarqux"))
+				.and(predicate::str::contains("Editor: emacs?")));
+		}		
 	}
 
 	#[cfg(test)]