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feat: implement select iterator utility function #1429

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merged 2 commits into from
Oct 15, 2023
Merged

feat: implement select iterator utility function #1429

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e0521ca
feat: implement `select` iterator utility function
ever0de Oct 15, 2023
9b8fac3
chore: add assert_eq for row
ever0de Oct 15, 2023
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33 changes: 33 additions & 0 deletions core/src/executor/execute.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -53,6 +53,39 @@ pub enum Payload {
ShowVariable(PayloadVariable),
}

impl Payload {
/// Exports `select` payloads as an [`std::iter::Iterator`].
///
/// The items of the Iterator are `HashMap<Column, Value>`, and they are borrowed by default.
/// If ownership is required, you need to acquire them directly.
///
/// - Some: [`Payload::Select`], [`Payload::SelectMap`]
/// - None: otherwise
pub fn select(&self) -> Option<impl Iterator<Item = HashMap<&str, &Value>>> {
#[derive(iter_enum::Iterator)]
enum Iter<I1, I2> {
Schema(I1),
Schemaless(I2),
}

Some(match self {
Payload::Select { labels, rows } => Iter::Schema(rows.iter().map(move |row| {
labels
.iter()
.zip(row.iter())
.map(|(label, value)| (label.as_str(), value))
.collect::<HashMap<_, _>>()
})),
Payload::SelectMap(rows) => Iter::Schemaless(rows.iter().map(|row| {
row.iter()
.map(|(k, v)| (k.as_str(), v))
.collect::<HashMap<_, _>>()
})),
_ => return None,
})
}
}

#[derive(Debug, Serialize, Deserialize, PartialEq, Eq)]
pub enum PayloadVariable {
Tables(Vec<String>),
Expand Down
63 changes: 17 additions & 46 deletions pkg/rust/examples/hello_world.rs
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Original file line number Diff line number Diff line change
@@ -1,56 +1,14 @@
#[cfg(feature = "sled-storage")]
mod hello_world {
use {
gluesql::{
prelude::{Glue, Payload},
sled_storage::SledStorage,
},
gluesql::{prelude::Glue, sled_storage::SledStorage},
std::fs,
};

struct GreetTable {
rows: Vec<GreetRow>,
}
struct GreetRow {
name: String,
}

impl TryFrom<Payload> for GreetTable {
type Error = &'static str;

fn try_from(payload: Payload) -> Result<Self, Self::Error> {
match payload {
Payload::Select { labels: _, rows } => {
let rows = rows
.into_iter()
.map(|mut row| {
let name = row.remove(0);
GreetRow {
name: String::from(name),
}
})
.collect::<Vec<_>>();

Ok(Self { rows })
}
Payload::SelectMap(rows) => {
let rows = rows
.into_iter()
.map(|row| {
let name = row.get("name").unwrap();
GreetRow {
name: String::from(name),
}
})
.collect::<Vec<_>>();

Ok(Self { rows })
}
_ => Err("unexpected payload, expected a select query result"),
}
}
}

pub async fn run() {
/*
Initiate a connection
Expand Down Expand Up @@ -92,10 +50,23 @@ mod hello_world {
*/
assert_eq!(result.len(), 1);

let table: GreetTable = result.remove(0).try_into().unwrap();
assert_eq!(table.rows.len(), 1);
let payload = result.remove(0);

let rows = payload
.select()
.unwrap()
.map(|map| {
let name = *map.get("name").unwrap();
let name = name.into();

GreetRow { name }
})
.collect::<Vec<_>>();

assert_eq!(rows.len(), 1);
assert_eq!(&rows[0].name, "World");

println!("Hello {}!", table.rows[0].name); // Will always output "Hello World!"
println!("Hello {}!", rows[0].name); // Will always output "Hello World!"
}
}

Expand Down
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