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Add example: "Filter csv records matching a predicate".

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Brahian E. Soto Mercedes 2017-08-22 10:00:12 +02:00 committed by Michał Budzyński
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54
src/encoding.md
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@ -12,6 +12,7 @@
| [Serialize records to CSV using Serde][ex-csv-serde] | [![csv-badge]][csv] [![serde-badge]][serde] | [![cat-encoding-badge]][cat-encoding] |
| [Handle invalid CSV data with Serde][ex-invalid-csv] | [![csv-badge]][csv] [![serde-badge]][serde] | [![cat-encoding-badge]][cat-encoding] |
| [Read CSV records with different delimeter][ex-csv-delimiter] | [![csv-badge]][csv] | [![cat-encoding-badge]][cat-encoding] |
| [Filter CSV records matching a predicate][ex-csv-filter] | [![csv-badge]][csv] | [![cat-encoding-badge]][cat-encoding] |
[ex-json-value]: #ex-json-value
<a name="ex-json-value"></a>
@ -543,6 +544,59 @@ Ashley-Zurich-92";
# quick_main!(run);
```
[ex-csv-filter]: #ex-csv-filter
<a name="ex-csv-filter"></a>
## Filter CSV records matching a predicate
[![csv-badge]][csv] [![cat-encoding-badge]][cat-encoding]
Returns _only_ the rows from `data` with a field that matches `query`.
```rust
# #[macro_use]
# extern crate error_chain;
extern crate csv;
use std::io;
#
# error_chain!{
# foreign_links {
# Io(std::io::Error);
# CsvError(csv::Error); // or just Seek(csv::Error)
# }
# }
fn run() -> Result<()> {
let query = "CA";
let data = "\
City,State,Population,Latitude,Longitude
Kenai,AK,7610,60.5544444,-151.2583333
Oakman,AL,,33.7133333,-87.3886111
Sandfort,AL,,32.3380556,-85.2233333
West Hollywood,CA,37031,34.0900000,-118.3608333";
let mut rdr = csv::ReaderBuilder::new().from_reader(data.as_bytes());
let mut wtr = csv::Writer::from_writer(io::stdout());
wtr.write_record(rdr.headers()?)?;
for result in rdr.records() {
let record = result?;
if record.iter().any(|field| field == query) {
wtr.write_record(&record)?;
}
}
wtr.flush()?;
Ok(())
}
#
# quick_main!(run);
```
_Disclaimer: this example has been adapted from [the csv crate tutorial](https://docs.rs/csv/*/csv/tutorial/index.html#filter-by-search)_.
<!-- Categories -->
[cat-encoding-badge]: https://badge-cache.kominick.com/badge/encoding--x.svg?style=social

2
src/intro.md
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@ -53,6 +53,7 @@ community. It needs and welcomes help. For details see
| [Serialize records to CSV using Serde][ex-csv-serde] | [![csv-badge]][csv] [![serde-badge]][serde] | [![cat-encoding-badge]][cat-encoding] |
| [Handle invalid CSV data with Serde][ex-invalid-csv] | [![csv-badge]][csv] [![serde-badge]][serde] | [![cat-encoding-badge]][cat-encoding] |
| [Read CSV records with different delimeter][ex-csv-delimiter] | [![csv-badge]][csv] | [![cat-encoding-badge]][cat-encoding] |
| [Filter CSV records matching a predicate][ex-csv-filter] | [![csv-badge]][csv] | [![cat-encoding-badge]][cat-encoding] |
## [Concurrency](concurrency.html)
@ -302,3 +303,4 @@ Keep lines sorted.
[ex-urlencoded]: encoding.html#ex-urlencoded
[ex-random-file-access]: basics.html#ex-random-file-access
[ex-regex-replace-named]: basics.html#ex-regex-replace-named
[ex-csv-filter]: encoding.html#ex-csv-filter