mirror of
https://github.com/nushell/nushell.git
synced 2024-11-07 09:04:18 +01:00
add metadata access
command (#13785)
# Description Add `metadata access`, which allows accessing/inspecting the metadata of a stream in a closure. ```nu ls | metadata access {|meta| ... } ``` - The metadata is provided as an argument to the closure, identical to the record obtained with `metadata` command. - `metadata access` passes its input stream into the closure as it is. - Within the closure, both the metadata and the stream are available. The closure may modify, collect or pass the stream as it is. # Motivation - Without this command, nu code can't act on metadata without losing the stream, use cases requiring both the stream and metadata must be implemented either as a built-in or a plugin. - This command allows users to enhance presentation of data, similar to `table` coloring the output of `ls`.
This commit is contained in:
parent
8d60c0d35d
commit
f63cecc316
109
crates/nu-command/src/debug/metadata_access.rs
Normal file
109
crates/nu-command/src/debug/metadata_access.rs
Normal file
@ -0,0 +1,109 @@
|
||||
use nu_engine::{command_prelude::*, get_eval_block_with_early_return};
|
||||
use nu_protocol::{
|
||||
engine::{Call, Closure, Command, EngineState, Stack},
|
||||
DataSource, PipelineData, PipelineMetadata, ShellError, Signature, SyntaxShape, Type, Value,
|
||||
};
|
||||
|
||||
#[derive(Clone)]
|
||||
pub struct MetadataAccess;
|
||||
|
||||
impl Command for MetadataAccess {
|
||||
fn name(&self) -> &str {
|
||||
"metadata access"
|
||||
}
|
||||
|
||||
fn description(&self) -> &str {
|
||||
"Access the metadata for the input stream within a closure."
|
||||
}
|
||||
|
||||
fn signature(&self) -> Signature {
|
||||
Signature::build("metadata access")
|
||||
.required(
|
||||
"closure",
|
||||
SyntaxShape::Closure(Some(vec![SyntaxShape::Record(vec![])])),
|
||||
"The closure to run with metadata access.",
|
||||
)
|
||||
.input_output_types(vec![(Type::Any, Type::Any)])
|
||||
.category(Category::Debug)
|
||||
}
|
||||
|
||||
fn run(
|
||||
&self,
|
||||
engine_state: &EngineState,
|
||||
caller_stack: &mut Stack,
|
||||
call: &Call,
|
||||
input: PipelineData,
|
||||
) -> Result<PipelineData, ShellError> {
|
||||
let closure: Closure = call.req(engine_state, caller_stack, 0)?;
|
||||
let block = engine_state.get_block(closure.block_id);
|
||||
|
||||
// `ClosureEvalOnce` is not used as it uses `Stack::captures_to_stack` rather than
|
||||
// `Stack::captures_to_stack_preserve_out_dest`. This command shouldn't collect streams
|
||||
let mut callee_stack = caller_stack.captures_to_stack_preserve_out_dest(closure.captures);
|
||||
let metadata_record = build_metadata_record(input.metadata().as_ref(), call.head);
|
||||
|
||||
if let Some(var_id) = block.signature.get_positional(0).and_then(|var| var.var_id) {
|
||||
callee_stack.add_var(var_id, metadata_record)
|
||||
}
|
||||
|
||||
let eval = get_eval_block_with_early_return(engine_state);
|
||||
eval(engine_state, &mut callee_stack, block, input)
|
||||
}
|
||||
|
||||
fn examples(&self) -> Vec<Example> {
|
||||
vec![Example {
|
||||
description: "Access metadata and data from a stream together",
|
||||
example: r#"{foo: bar} | to json --raw | metadata access {|meta| {in: $in, meta: $meta}}"#,
|
||||
result: Some(Value::test_record(record! {
|
||||
"in" => Value::test_string(r#"{"foo":"bar"}"#),
|
||||
"meta" => Value::test_record(record! {
|
||||
"content_type" => Value::test_string(r#"application/json"#)
|
||||
})
|
||||
})),
|
||||
}]
|
||||
}
|
||||
}
|
||||
|
||||
fn build_metadata_record(metadata: Option<&PipelineMetadata>, head: Span) -> Value {
|
||||
let mut record = Record::new();
|
||||
|
||||
if let Some(x) = metadata {
|
||||
match x {
|
||||
PipelineMetadata {
|
||||
data_source: DataSource::Ls,
|
||||
..
|
||||
} => record.push("source", Value::string("ls", head)),
|
||||
PipelineMetadata {
|
||||
data_source: DataSource::HtmlThemes,
|
||||
..
|
||||
} => record.push("source", Value::string("into html --list", head)),
|
||||
PipelineMetadata {
|
||||
data_source: DataSource::FilePath(path),
|
||||
..
|
||||
} => record.push(
|
||||
"source",
|
||||
Value::string(path.to_string_lossy().to_string(), head),
|
||||
),
|
||||
_ => {}
|
||||
}
|
||||
if let Some(ref content_type) = x.content_type {
|
||||
record.push("content_type", Value::string(content_type, head));
|
||||
}
|
||||
}
|
||||
|
||||
Value::record(record, head)
|
||||
}
|
||||
|
||||
#[cfg(test)]
|
||||
mod test {
|
||||
use crate::ToJson;
|
||||
|
||||
use super::*;
|
||||
|
||||
#[test]
|
||||
fn test_examples() {
|
||||
use crate::test_examples_with_commands;
|
||||
|
||||
test_examples_with_commands(MetadataAccess {}, &[&ToJson])
|
||||
}
|
||||
}
|
@ -5,6 +5,7 @@ mod info;
|
||||
mod inspect;
|
||||
mod inspect_table;
|
||||
mod metadata;
|
||||
mod metadata_access;
|
||||
mod metadata_set;
|
||||
mod profile;
|
||||
mod timeit;
|
||||
@ -21,6 +22,7 @@ pub use info::DebugInfo;
|
||||
pub use inspect::Inspect;
|
||||
pub use inspect_table::build_table;
|
||||
pub use metadata::Metadata;
|
||||
pub use metadata_access::MetadataAccess;
|
||||
pub use metadata_set::MetadataSet;
|
||||
pub use profile::DebugProfile;
|
||||
pub use timeit::TimeIt;
|
||||
|
@ -151,6 +151,7 @@ pub fn add_shell_command_context(mut engine_state: EngineState) -> EngineState {
|
||||
Explain,
|
||||
Inspect,
|
||||
Metadata,
|
||||
MetadataAccess,
|
||||
MetadataSet,
|
||||
TimeIt,
|
||||
View,
|
||||
|
Loading…
Reference in New Issue
Block a user