Added the ability to open json lines dataframes with polars lazy json…

… lines reader. (#13167)

The `--lazy` flag will now use the polars' LazyJsonLinesReader when
opening a json lines file with `polars open`

crates/nu_plugin_polars/src/dataframe/eager/open.rs

@@ -19,9 +19,12 @@ use std::{
  sync::Arc,
 };
 
-use polars::prelude::{
- CsvEncoding, IpcReader, JsonFormat, JsonReader, LazyCsvReader, LazyFileListReader, LazyFrame,
- ParquetReader, ScanArgsIpc, ScanArgsParquet, SerReader,
+use polars::{
+ lazy::frame::LazyJsonLineReader,
+ prelude::{
+ CsvEncoding, IpcReader, JsonFormat, JsonReader, LazyCsvReader, LazyFileListReader,
+ LazyFrame, ParquetReader, ScanArgsIpc, ScanArgsParquet, SerReader,
+ },
 };
 
 use polars_io::{
@@ -375,36 +378,51 @@ fn from_jsonl(
  .get_flag("schema")?
  .map(|schema| NuSchema::try_from(&schema))
  .transpose()?;
- let file = File::open(file_path).map_err(|e| ShellError::GenericError {
- error: "Error opening file".into(),
- msg: e.to_string(),
- span: Some(file_span),
- help: None,
- inner: vec![],
- })?;
-
- let buf_reader = BufReader::new(file);
- let reader = JsonReader::new(buf_reader)
- .with_json_format(JsonFormat::JsonLines)
- .infer_schema_len(infer_schema);
-
- let reader = match maybe_schema {
- Some(schema) => reader.with_schema(schema.into()),
- None => reader,
- };
-
- let df: NuDataFrame = reader
- .finish()
- .map_err(|e| ShellError::GenericError {
- error: "Json lines reader error".into(),
- msg: format!("{e:?}"),
- span: Some(call.head),
+ if call.has_flag("lazy")? {
+ let df = LazyJsonLineReader::new(file_path)
+ .with_infer_schema_length(infer_schema)
+ .with_schema(maybe_schema.map(|s| s.into()))
+ .finish()
+ .map_err(|e| ShellError::GenericError {
+ error: format!("Json lines reader error: {e}"),
+ msg: "".into(),
+ span: Some(call.head),
+ help: None,
+ inner: vec![],
+ })?;
+ let df = NuLazyFrame::new(false, df);
+ df.cache_and_to_value(plugin, engine, call.head)
+ } else {
+ let file = File::open(file_path).map_err(|e| ShellError::GenericError {
+ error: "Error opening file".into(),
+ msg: e.to_string(),
+ span: Some(file_span),
  help: None,
  inner: vec![],
- })?
- .into();
+ })?;
+ let buf_reader = BufReader::new(file);
+ let reader = JsonReader::new(buf_reader)
+ .with_json_format(JsonFormat::JsonLines)
+ .infer_schema_len(infer_schema);
 
- df.cache_and_to_value(plugin, engine, call.head)
+ let reader = match maybe_schema {
+ Some(schema) => reader.with_schema(schema.into()),
+ None => reader,
+ };
+
+ let df: NuDataFrame = reader
+ .finish()
+ .map_err(|e| ShellError::GenericError {
+ error: "Json lines reader error".into(),
+ msg: format!("{e:?}"),
+ span: Some(call.head),
+ help: None,
+ inner: vec![],
+ })?
+ .into();
+
+ df.cache_and_to_value(plugin, engine, call.head)
+ }
 }
 
 fn from_csv(