nushell/crates/nu-command/src/dataframe/eager/to_csv.rs
Darren Schroeder 5e70d4121a
Add dfr to dataframe cmds (#7998)
# Description

This PR tries to resolve the overloading issue by going back to our
original naming convention for dataframes. So, this PR renames all
dataframe commands with a prefix of `dfr`. Some commands like `open-df`
were renamed to `dfr open` and things like `into df` were renamed `dfr
into-df`. I'm sure we can optimize naming a bit, but it seems to compile
now.

# User-Facing Changes

All dataframe commands are prefixed with dfr.

# Tests + Formatting

Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A
clippy::needless_collect` to check that you're using the standard code
style
- `cargo test --workspace` to check that all tests pass

# After Submitting

If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.
2023-02-08 15:52:57 -06:00

141 lines
3.8 KiB
Rust

use std::{fs::File, path::PathBuf};
use nu_engine::CallExt;
use nu_protocol::{
ast::Call,
engine::{Command, EngineState, Stack},
Category, Example, PipelineData, ShellError, Signature, Spanned, SyntaxShape, Type, Value,
};
use polars::prelude::{CsvWriter, SerWriter};
use super::super::values::NuDataFrame;
#[derive(Clone)]
pub struct ToCSV;
impl Command for ToCSV {
fn name(&self) -> &str {
"dfr to-csv"
}
fn usage(&self) -> &str {
"Saves dataframe to csv file"
}
fn signature(&self) -> Signature {
Signature::build(self.name())
.required("file", SyntaxShape::Filepath, "file path to save dataframe")
.named(
"delimiter",
SyntaxShape::String,
"file delimiter character",
Some('d'),
)
.switch("no-header", "Indicates if file doesn't have header", None)
.input_type(Type::Custom("dataframe".into()))
.output_type(Type::Any)
.category(Category::Custom("dataframe".into()))
}
fn examples(&self) -> Vec<Example> {
vec![
Example {
description: "Saves dataframe to csv file",
example: "[[a b]; [1 2] [3 4]] | dfr into-df | dfr to-csv test.csv",
result: None,
},
Example {
description: "Saves dataframe to csv file using other delimiter",
example: "[[a b]; [1 2] [3 4]] | dfr into-df | dfr to-csv test.csv -d '|'",
result: None,
},
]
}
fn run(
&self,
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
command(engine_state, stack, call, input)
}
}
fn command(
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
let file_name: Spanned<PathBuf> = call.req(engine_state, stack, 0)?;
let delimiter: Option<Spanned<String>> = call.get_flag(engine_state, stack, "delimiter")?;
let no_header: bool = call.has_flag("no-header");
let mut df = NuDataFrame::try_from_pipeline(input, call.head)?;
let mut file = File::create(&file_name.item).map_err(|e| {
ShellError::GenericError(
"Error with file name".into(),
e.to_string(),
Some(file_name.span),
None,
Vec::new(),
)
})?;
let writer = CsvWriter::new(&mut file);
let writer = if no_header {
writer.has_header(false)
} else {
writer.has_header(true)
};
let mut writer = match delimiter {
None => writer,
Some(d) => {
if d.item.len() != 1 {
return Err(ShellError::GenericError(
"Incorrect delimiter".into(),
"Delimiter has to be one char".into(),
Some(d.span),
None,
Vec::new(),
));
} else {
let delimiter = match d.item.chars().next() {
Some(d) => d as u8,
None => unreachable!(),
};
writer.with_delimiter(delimiter)
}
}
};
writer.finish(df.as_mut()).map_err(|e| {
ShellError::GenericError(
"Error writing to file".into(),
e.to_string(),
Some(file_name.span),
None,
Vec::new(),
)
})?;
let file_value = Value::String {
val: format!("saved {:?}", &file_name.item),
span: file_name.span,
};
Ok(PipelineData::Value(
Value::List {
vals: vec![file_value],
span: call.head,
},
None,
))
}