nu_command/debug/
metadata_access.rs

1use nu_engine::{ClosureEvalOnce, command_prelude::*};
2use nu_protocol::{
3    PipelineData, ShellError, Signature, SyntaxShape, Type, Value,
4    engine::{Call, Closure, Command, EngineState, Stack},
5};
6
7use super::util::build_metadata_record;
8
9#[derive(Clone)]
10pub struct MetadataAccess;
11
12impl Command for MetadataAccess {
13    fn name(&self) -> &str {
14        "metadata access"
15    }
16
17    fn description(&self) -> &str {
18        "Access the metadata for the input stream within a closure."
19    }
20
21    fn signature(&self) -> Signature {
22        Signature::build("metadata access")
23            .required(
24                "closure",
25                SyntaxShape::Closure(Some(vec![SyntaxShape::Record(vec![])])),
26                "The closure to run with metadata access.",
27            )
28            .input_output_types(vec![(Type::Any, Type::Any)])
29            .category(Category::Debug)
30    }
31
32    fn run(
33        &self,
34        engine_state: &EngineState,
35        caller_stack: &mut Stack,
36        call: &Call,
37        input: PipelineData,
38    ) -> Result<PipelineData, ShellError> {
39        let closure: Closure = call.req(engine_state, caller_stack, 0)?;
40        let metadata_record = Value::record(build_metadata_record(&input, call.head), call.head);
41
42        ClosureEvalOnce::new_env_preserve_out_dest(engine_state, caller_stack, closure)
43            .add_arg(metadata_record)?
44            .run_with_input(input)
45    }
46
47    fn examples(&self) -> Vec<Example<'_>> {
48        vec![Example {
49            description: "Access metadata and data from a stream together.",
50            example: "{foo: bar} | to json --raw | metadata access {|meta| {in: $in, content: $meta.content_type}}",
51            result: Some(Value::test_record(record! {
52                "in" => Value::test_string(r#"{"foo":"bar"}"#),
53                "content" => Value::test_string("application/json")
54            })),
55        }]
56    }
57}
58
59#[cfg(test)]
60mod test {
61    use super::*;
62
63    #[test]
64    fn test_examples() -> nu_test_support::Result {
65        nu_test_support::test().examples(MetadataAccess)
66    }
67}
nu_command/debug/metadata_access.rs

nu_command/debug/
metadata_access.rs
