Struct csv::ByteRecord

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pub struct ByteRecord(/* private fields */);
Expand description

A single CSV record stored as raw bytes.

A byte record permits reading or writing CSV rows that are not UTF-8. In general, you should prefer using a StringRecord since it is more ergonomic, but a ByteRecord is provided in case you need it.

If you are using the Serde (de)serialization APIs, then you probably never need to interact with a ByteRecord or a StringRecord. However, there are some circumstances in which you might need to use a raw record type while still using Serde. For example, if you need to deserialize possibly invalid UTF-8 fields, then you’ll need to first read your record into a ByteRecord, and then use ByteRecord::deserialize to run Serde. Another reason for using the raw record deserialization APIs is if you’re using Serde to read into borrowed data such as a &'a str or a &'a [u8].

Two ByteRecords are compared on the basis of their field data. Any position information associated with the records is ignored.

Implementations§

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impl ByteRecord

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pub fn new() -> ByteRecord

Create a new empty ByteRecord.

Note that you may find the ByteRecord::from constructor more convenient, which is provided by an impl on the From trait.

Example: create an empty record
use csv::ByteRecord;

let record = ByteRecord::new();
assert_eq!(record.len(), 0);
Example: initialize a record from a Vec
use csv::ByteRecord;

let record = ByteRecord::from(vec!["a", "b", "c"]);
assert_eq!(record.len(), 3);
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pub fn with_capacity(buffer: usize, fields: usize) -> ByteRecord

Create a new empty ByteRecord with the given capacity settings.

buffer refers to the capacity of the buffer used to store the actual row contents. fields refers to the number of fields one might expect to store.

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pub fn deserialize<'de, D: Deserialize<'de>>( &'de self, headers: Option<&'de ByteRecord> ) -> Result<D>

Deserialize this record.

The D type parameter refers to the type that this record should be deserialized into. The 'de lifetime refers to the lifetime of the ByteRecord. The 'de lifetime permits deserializing into structs that borrow field data from this record.

An optional headers parameter permits deserializing into a struct based on its field names (corresponding to header values) rather than the order in which the fields are defined.

Example: without headers

This shows how to deserialize a single row into a struct based on the order in which fields occur. This example also shows how to borrow fields from the ByteRecord, which results in zero allocation deserialization.

use std::error::Error;

use csv::ByteRecord;
use serde::Deserialize;

#[derive(Deserialize)]
struct Row<'a> {
    city: &'a str,
    country: &'a str,
    population: u64,
}

fn example() -> Result<(), Box<dyn Error>> {
    let record = ByteRecord::from(vec![
        "Boston", "United States", "4628910",
    ]);

    let row: Row = record.deserialize(None)?;
    assert_eq!(row.city, "Boston");
    assert_eq!(row.country, "United States");
    assert_eq!(row.population, 4628910);
    Ok(())
}
Example: with headers

This example is like the previous one, but shows how to deserialize into a struct based on the struct’s field names. For this to work, you must provide a header row.

This example also shows that you can deserialize into owned data types (e.g., String) instead of borrowed data types (e.g., &str).

use std::error::Error;

use csv::ByteRecord;
use serde::Deserialize;

#[derive(Deserialize)]
struct Row {
    city: String,
    country: String,
    population: u64,
}

fn example() -> Result<(), Box<dyn Error>> {
    // Notice that the fields are not in the same order
    // as the fields in the struct!
    let header = ByteRecord::from(vec![
        "country", "city", "population",
    ]);
    let record = ByteRecord::from(vec![
        "United States", "Boston", "4628910",
    ]);

    let row: Row = record.deserialize(Some(&header))?;
    assert_eq!(row.city, "Boston");
    assert_eq!(row.country, "United States");
    assert_eq!(row.population, 4628910);
    Ok(())
}
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pub fn iter(&self) -> ByteRecordIter<'_>

Returns an iterator over all fields in this record.

Example

This example shows how to iterate over each field in a ByteRecord.

use csv::ByteRecord;

let record = ByteRecord::from(vec!["a", "b", "c"]);
for field in record.iter() {
    assert!(field == b"a" || field == b"b" || field == b"c");
}
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pub fn get(&self, i: usize) -> Option<&[u8]>

Return the field at index i.

If no field at index i exists, then this returns None.

Example
use csv::ByteRecord;

let record = ByteRecord::from(vec!["a", "b", "c"]);
assert_eq!(record.get(1), Some(&b"b"[..]));
assert_eq!(record.get(3), None);
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pub fn is_empty(&self) -> bool

Returns true if and only if this record is empty.

Example
use csv::ByteRecord;

assert!(ByteRecord::new().is_empty());
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pub fn len(&self) -> usize

Returns the number of fields in this record.

Example
use csv::ByteRecord;

let record = ByteRecord::from(vec!["a", "b", "c"]);
assert_eq!(record.len(), 3);
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pub fn truncate(&mut self, n: usize)

Truncate this record to n fields.

If n is greater than the number of fields in this record, then this has no effect.

Example
use csv::ByteRecord;

let mut record = ByteRecord::from(vec!["a", "b", "c"]);
assert_eq!(record.len(), 3);
record.truncate(1);
assert_eq!(record.len(), 1);
assert_eq!(record, vec!["a"]);
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pub fn clear(&mut self)

Clear this record so that it has zero fields.

This is equivalent to calling truncate(0).

Note that it is not necessary to clear the record to reuse it with the CSV reader.

Example
use csv::ByteRecord;

let mut record = ByteRecord::from(vec!["a", "b", "c"]);
assert_eq!(record.len(), 3);
record.clear();
assert_eq!(record.len(), 0);
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pub fn trim(&mut self)

Trim the fields of this record so that leading and trailing whitespace is removed.

This method uses the ASCII definition of whitespace. That is, only bytes in the class [\t\n\v\f\r ] are trimmed.

Example
use csv::ByteRecord;

let mut record = ByteRecord::from(vec![
    "  ", "\tfoo", "bar  ", "b a z",
]);
record.trim();
assert_eq!(record, vec!["", "foo", "bar", "b a z"]);
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pub fn push_field(&mut self, field: &[u8])

Add a new field to this record.

Example
use csv::ByteRecord;

let mut record = ByteRecord::new();
record.push_field(b"foo");
assert_eq!(&record[0], b"foo");
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pub fn position(&self) -> Option<&Position>

Return the position of this record, if available.

Example
use std::error::Error;

use csv::{ByteRecord, ReaderBuilder};

fn example() -> Result<(), Box<dyn Error>> {
    let mut record = ByteRecord::new();
    let mut rdr = ReaderBuilder::new()
        .has_headers(false)
        .from_reader("a,b,c\nx,y,z".as_bytes());

    assert!(rdr.read_byte_record(&mut record)?);
    {
        let pos = record.position().expect("a record position");
        assert_eq!(pos.byte(), 0);
        assert_eq!(pos.line(), 1);
        assert_eq!(pos.record(), 0);
    }

    assert!(rdr.read_byte_record(&mut record)?);
    {
        let pos = record.position().expect("a record position");
        assert_eq!(pos.byte(), 6);
        assert_eq!(pos.line(), 2);
        assert_eq!(pos.record(), 1);
    }

    // Finish the CSV reader for good measure.
    assert!(!rdr.read_byte_record(&mut record)?);
    Ok(())
}
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pub fn set_position(&mut self, pos: Option<Position>)

Set the position of this record.

Example
use csv::{ByteRecord, Position};

let mut record = ByteRecord::from(vec!["a", "b", "c"]);
let mut pos = Position::new();
pos.set_byte(100);
pos.set_line(4);
pos.set_record(2);

record.set_position(Some(pos.clone()));
assert_eq!(record.position(), Some(&pos));
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pub fn range(&self, i: usize) -> Option<Range<usize>>

Return the start and end position of a field in this record.

If no such field exists at the given index, then return None.

The range returned can be used with the slice returned by as_slice.

Example
use csv::ByteRecord;

let record = ByteRecord::from(vec!["foo", "quux", "z"]);
let range = record.range(1).expect("a record range");
assert_eq!(&record.as_slice()[range], &b"quux"[..]);
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pub fn as_slice(&self) -> &[u8]

Return the entire row as a single byte slice. The slice returned stores all fields contiguously. The boundaries of each field can be determined via the range method.

Example
use csv::ByteRecord;

let record = ByteRecord::from(vec!["foo", "quux", "z"]);
assert_eq!(record.as_slice(), &b"fooquuxz"[..]);

Trait Implementations§

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impl Clone for ByteRecord

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fn clone(&self) -> ByteRecord

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for ByteRecord

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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impl Default for ByteRecord

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fn default() -> ByteRecord

Returns the “default value” for a type. Read more
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impl<T: AsRef<[u8]>> Extend<T> for ByteRecord

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fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I)

Extends a collection with the contents of an iterator. Read more
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fn extend_one(&mut self, item: A)

🔬This is a nightly-only experimental API. (extend_one)
Extends a collection with exactly one element.
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fn extend_reserve(&mut self, additional: usize)

🔬This is a nightly-only experimental API. (extend_one)
Reserves capacity in a collection for the given number of additional elements. Read more
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impl<'a, T: AsRef<[u8]>> From<&'a [T]> for ByteRecord

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fn from(xs: &'a [T]) -> ByteRecord

Converts to this type from the input type.
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impl From<StringRecord> for ByteRecord

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fn from(record: StringRecord) -> ByteRecord

Converts to this type from the input type.
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impl<T: AsRef<[u8]>> From<Vec<T, Global>> for ByteRecord

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fn from(xs: Vec<T>) -> ByteRecord

Converts to this type from the input type.
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impl<T: AsRef<[u8]>> FromIterator<T> for ByteRecord

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fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> ByteRecord

Creates a value from an iterator. Read more
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impl Index<usize> for ByteRecord

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type Output = [u8]

The returned type after indexing.
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fn index(&self, i: usize) -> &[u8]

Performs the indexing (container[index]) operation. Read more
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impl<'r> IntoIterator for &'r ByteRecord

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type IntoIter = ByteRecordIter<'r>

Which kind of iterator are we turning this into?
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type Item = &'r [u8]

The type of the elements being iterated over.
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fn into_iter(self) -> ByteRecordIter<'r>

Creates an iterator from a value. Read more
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impl<'a, T: AsRef<[u8]>> PartialEq<[T]> for &'a ByteRecord

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fn eq(&self, other: &[T]) -> bool

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl<T: AsRef<[u8]>> PartialEq<[T]> for ByteRecord

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fn eq(&self, other: &[T]) -> bool

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl PartialEq<ByteRecord> for ByteRecord

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fn eq(&self, other: &ByteRecord) -> bool

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl<'a, T: AsRef<[u8]>> PartialEq<Vec<T, Global>> for &'a ByteRecord

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fn eq(&self, other: &Vec<T>) -> bool

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl<T: AsRef<[u8]>> PartialEq<Vec<T, Global>> for ByteRecord

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fn eq(&self, other: &Vec<T>) -> bool

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl Eq for ByteRecord

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impl StructuralEq for ByteRecord

Auto Trait Implementations§

Blanket Implementations§

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impl<T> Any for Twhere T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for Twhere T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for Twhere T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for Twhere U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> ToOwned for Twhere T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for Twhere U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for Twhere U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.