From a1b6360da5b5d21da207536f1810abfe34796c3b Mon Sep 17 00:00:00 2001
From: Turiiya <34311583+ttytm@users.noreply.github.com>
Date: Tue, 2 Apr 2024 04:32:11 +0200
Subject: [PATCH] x.json2: add ability to decode arrays (#21163)

---
 vlib/x/json2/decoder.v            | 33 +++++++++++++++++++++++++++++++
 vlib/x/json2/tests/decoder_test.v | 24 +++++++++++++++++++---
 2 files changed, 54 insertions(+), 3 deletions(-)

diff --git a/vlib/x/json2/decoder.v b/vlib/x/json2/decoder.v
index 5683eff4e03f27..c0a977aefab08e 100644
--- a/vlib/x/json2/decoder.v
+++ b/vlib/x/json2/decoder.v
@@ -249,6 +249,39 @@ fn decode_struct[T](_ T, res map[string]Any) !T {
 						typ.$(field.name) = res[json_name]!.to_time()!
 					}
 				} $else $if field.is_array {
+					arr := res[field.name]! as []Any
+					match typeof(typ.$(field.name)).name {
+						'[]bool' { typ.$(field.name) = arr.map(it.bool()) }
+						'[]?bool' { typ.$(field.name) = arr.map(?bool(it.bool())) }
+						'[]f32' { typ.$(field.name) = arr.map(it.f32()) }
+						'[]?f32' { typ.$(field.name) = arr.map(?f32(it.f32())) }
+						'[]f64' { typ.$(field.name) = arr.map(it.f64()) }
+						'[]?f64' { typ.$(field.name) = arr.map(?f64(it.f64())) }
+						'[]i8' { typ.$(field.name) = arr.map(it.i8()) }
+						'[]?i8' { typ.$(field.name) = arr.map(?i8(it.i8())) }
+						'[]i16' { typ.$(field.name) = arr.map(it.i16()) }
+						'[]?i16' { typ.$(field.name) = arr.map(?i16(it.i16())) }
+						'[]i64' { typ.$(field.name) = arr.map(it.i64()) }
+						'[]?i64' { typ.$(field.name) = arr.map(?i64(it.i64())) }
+						'[]int' { typ.$(field.name) = arr.map(it.int()) }
+						'[]?int' { typ.$(field.name) = arr.map(?int(it.int())) }
+						'[]string' { typ.$(field.name) = arr.map(it.str()) }
+						'[]?string' { typ.$(field.name) = arr.map(?string(it.str())) }
+						// NOTE: Using `!` on `to_time()` inside the array method causes a builder error - 2024/04/01.
+						'[]time.Time' { typ.$(field.name) = arr.map(it.to_time() or { time.Time{} }) }
+						// vfmt off
+						'[]?time.Time' { typ.$(field.name) = arr.map(?time.Time(it.to_time() or { time.Time{} })) }
+						// vfmt on
+						'[]u8' { typ.$(field.name) = arr.map(it.u64()) }
+						'[]?u8' { typ.$(field.name) = arr.map(?u8(it.u64())) }
+						'[]u16' { typ.$(field.name) = arr.map(it.u64()) }
+						'[]?u16' { typ.$(field.name) = arr.map(?u16(it.u64())) }
+						'[]u32' { typ.$(field.name) = arr.map(it.u64()) }
+						'[]?u32' { typ.$(field.name) = arr.map(?u32(it.u64())) }
+						'[]u64' { typ.$(field.name) = arr.map(it.u64()) }
+						'[]?u64' { typ.$(field.name) = arr.map(?u64(it.u64())) }
+						else {}
+					}
 				} $else $if field.is_struct {
 					typ.$(field.name) = decode_struct(typ.$(field.name), res[field.name]!.as_map())!
 				} $else $if field.is_alias {
diff --git a/vlib/x/json2/tests/decoder_test.v b/vlib/x/json2/tests/decoder_test.v
index 8532302ae1467b..ca193f6959ab48 100644
--- a/vlib/x/json2/tests/decoder_test.v
+++ b/vlib/x/json2/tests/decoder_test.v
@@ -83,6 +83,24 @@ fn test_raw_decode_array_invalid() {
 	assert false
 }
 
+struct Foo {
+	int  []int
+	str  []string
+	f32  []f32
+	oint []?int
+}
+
+fn test_decode_array_fields() {
+	input := '{"int":[0, 1], "str":["2", "3"], "f32": [4.0, 5.0], "oint": [6, null]}'
+	foo := json.decode[Foo](input)!
+	assert foo.int == [0, 1]
+	assert foo.str == ['2', '3']
+	assert foo.f32 == [f32(4.0), 5.0]
+	a, b := foo.oint[0], foo.oint[1]
+	assert a? == 6
+	assert b? == 0
+}
+
 struct ContactItem {
 	description string
 	telnr       string
@@ -95,9 +113,9 @@ struct User {
 }
 
 fn test_decode_missing_comma() {
-	data := '{ 
-				"name": "Frodo", 
-				"age": 25 
+	data := '{
+				"name": "Frodo",
+				"age": 25
 				"contact": {
 					"description": "descr",
 					"telnr": "+32333"