provide a common implementation for query string conversions in url join and url build-query (#14173)

Addresses one of the points in #14162

# Description

Factors out part of the `url::build_query::to_url` function into a
separate function `url::query::record_to_qs()`, which is then used in
both `url::build_query` and `url::join`.

# User-Facing Changes

Like with `url build-query` (after #14073), `url join` will allow list
values in `params` and behavior of two commands will be same.

```nushell
> {a: ["one", "two"], b: "three"} | url build-query
"a=one&a=two&b=three"

> {scheme: "http", host: "host", params: {a: ["one", "two"], b: "three"}} | url join 
"http://host?a=one&a=two&b=three"
```

# Tests + Formatting

Added an example to `url join` for the new behavior.

crates/nu-command/src/network/url/build_query.rs

@@ -1,5 +1,7 @@
 use nu_engine::command_prelude::*;
 
+use super::query::record_to_query_string;
+
 #[derive(Clone)]
 pub struct SubCommand;
 
@@ -38,12 +40,12 @@ impl Command for SubCommand {
                 result: Some(Value::test_string("foo=1&bar=2")),
             },
             Example {
-                description: "Outputs a query string representing the contents of this record",
+                description: "Outputs a query string representing the contents of this record, with a value that needs to be url-encoded",
                 example: r#"{a:"AT&T", b: "AT T"} | url build-query"#,
                 result: Some(Value::test_string("a=AT%26T&b=AT+T")),
             },
             Example {
-                description: "Outputs a query string representing the contents of this record",
+                description: "Outputs a query string representing the contents of this record, \"exploding\" the list into multiple parameters",
                 example: r#"{a: ["one", "two"], b: "three"} | url build-query"#,
                 result: Some(Value::test_string("a=one&a=two&b=three")),
             },
@@ -68,48 +70,7 @@ fn to_url(input: PipelineData, head: Span) -> Result<PipelineData, ShellError> {
         .map(move |value| {
             let span = value.span();
             match value {
-                Value::Record { ref val, .. } => {
-                    let mut row_vec = vec![];
-                    for (k, v) in &**val {
-                        match v {
-                            Value::List { ref vals, .. } => {
-                                for v_item in vals {
-                                    row_vec.push((
-                                        k.clone(),
-                                        v_item.coerce_string().map_err(|_| {
-                                            ShellError::UnsupportedInput {
-                                                msg: "Expected a record with list of string values"
-                                                    .to_string(),
-                                                input: "value originates from here".into(),
-                                                msg_span: head,
-                                                input_span: span,
-                                            }
-                                        })?,
-                                    ));
-                                }
-                            }
-                            _ => row_vec.push((
-                                k.clone(),
-                                v.coerce_string()
-                                    .map_err(|_| ShellError::UnsupportedInput {
-                                        msg:
-                                            "Expected a record with string or list of string values"
-                                                .to_string(),
-                                        input: "value originates from here".into(),
-                                        msg_span: head,
-                                        input_span: span,
-                                    })?,
-                            )),
-                        }
-                    }
-
-                    serde_urlencoded::to_string(row_vec).map_err(|_| ShellError::CantConvert {
-                        to_type: "URL".into(),
-                        from_type: value.get_type().to_string(),
-                        span: head,
-                        help: None,
-                    })
-                }
+                Value::Record { ref val, .. } => record_to_query_string(val, span, head),
                 // Propagate existing errors
                 Value::Error { error, .. } => Err(*error),
                 other => Err(ShellError::UnsupportedInput {

crates/nu-command/src/network/url/join.rs

@@ -1,5 +1,7 @@
 use nu_engine::command_prelude::*;
 
+use super::query::record_to_query_string;
+
 #[derive(Clone)]
 pub struct SubCommand;
 
@@ -27,7 +29,7 @@ impl Command for SubCommand {
     fn examples(&self) -> Vec<Example> {
         vec![
             Example {
-                description: "Outputs a url representing the contents of this record",
+                description: "Outputs a url representing the contents of this record, `params` and `query` fields must be equivalent",
                 example: r#"{
         "scheme": "http",
         "username": "",
@@ -47,6 +49,21 @@ impl Command for SubCommand {
                     "http://www.pixiv.net/member_illust.php?mode=medium&illust_id=99260204",
                 )),
             },
+            Example {
+                description: "Outputs a url representing the contents of this record, \"exploding\" the list in `params` into multiple parameters",
+                example: r#"{
+        "scheme": "http",
+        "username": "user",
+        "password": "pwd",
+        "host": "www.pixiv.net",
+        "port": "1234",
+        "params": {a: ["one", "two"], b: "three"},
+        "fragment": ""
+    } | url join"#,
+                result: Some(Value::test_string(
+                    "http://user:pwd@www.pixiv.net:1234?a=one&a=two&b=three",
+                )),
+            },
             Example {
                 description: "Outputs a url representing the contents of this record",
                 example: r#"{
@@ -178,16 +195,8 @@ impl UrlComponents {
 
         if key == "params" {
             return match value {
-                Value::Record { val, .. } => {
-                    let mut qs = val
-                        .into_owned()
-                        .into_iter()
-                        .map(|(k, v)| match v.coerce_into_string() {
-                            Ok(val) => Ok(format!("{k}={val}")),
-                            Err(err) => Err(err),
-                        })
-                        .collect::<Result<Vec<String>, ShellError>>()?
-                        .join("&");
+                Value::Record { ref val, .. } => {
+                    let mut qs = record_to_query_string(val, value_span, span)?;
 
                     qs = if !qs.trim().is_empty() {
                         format!("?{qs}")

crates/nu-command/src/network/url/mod.rs

@@ -3,6 +3,7 @@ mod decode;
 mod encode;
 mod join;
 mod parse;
+mod query;
 mod url_;
 
 pub use self::parse::SubCommand as UrlParse;

crates/nu-command/src/network/url/query.rs

@@ -0,0 +1,44 @@
+use nu_protocol::{Record, ShellError, Span, Type, Value};
+
+pub fn record_to_query_string(
+    record: &Record,
+    span: Span,
+    head: Span,
+) -> Result<String, ShellError> {
+    let mut row_vec = vec![];
+    for (k, v) in record {
+        match v {
+            Value::List { ref vals, .. } => {
+                for v_item in vals {
+                    row_vec.push((
+                        k.as_str(),
+                        v_item
+                            .coerce_str()
+                            .map_err(|_| ShellError::UnsupportedInput {
+                                msg: "Expected a record with list of string values".to_string(),
+                                input: "value originates from here".into(),
+                                msg_span: head,
+                                input_span: span,
+                            })?,
+                    ));
+                }
+            }
+            _ => row_vec.push((
+                k.as_str(),
+                v.coerce_str().map_err(|_| ShellError::UnsupportedInput {
+                    msg: "Expected a record with string or list of string values".to_string(),
+                    input: "value originates from here".into(),
+                    msg_span: head,
+                    input_span: span,
+                })?,
+            )),
+        }
+    }
+
+    serde_urlencoded::to_string(row_vec).map_err(|_| ShellError::CantConvert {
+        to_type: "URL".into(),
+        from_type: Type::record().to_string(),
+        span: head,
+        help: None,
+    })
+}