Fixes #5761.

lib/pure/json.nim

@@ -1608,7 +1608,7 @@ proc createConstructor(typeSym, jsonNode: NimNode): NimNode =
       result = processType(newIdentNode(typeName), obj, jsonNode, true)
     of "seq":
       let seqT = typeSym[1]
-      let forLoopI = newIdentNode("i")
+      let forLoopI = genSym(nskForVar, "i")
       let indexerNode = createJsonIndexer(jsonNode, forLoopI)
       let constructorNode = createConstructor(seqT, indexerNode)
 
@@ -1616,12 +1616,25 @@ proc createConstructor(typeSym, jsonNode: NimNode): NimNode =
       result = quote do:
         (
           var list: `typeSym` = @[];
-          # if `jsonNode`.kind != JArray:
-          #   # TODO: Improve error message.
-          #   raise newException(ValueError, "Expected a list")
+          verifyJsonKind(`jsonNode`, {JArray}, astToStr(`jsonNode`));
           for `forLoopI` in 0 .. <`jsonNode`.len: list.add(`constructorNode`);
           list
         )
+    of "array":
+      let arrayT = typeSym[2]
+      let forLoopI = genSym(nskForVar, "i")
+      let indexerNode = createJsonIndexer(jsonNode, forLoopI)
+      let constructorNode = createConstructor(arrayT, indexerNode)
+
+      # Create a statement expression containing a for loop.
+      result = quote do:
+        (
+          var list: `typeSym`;
+          verifyJsonKind(`jsonNode`, {JArray}, astToStr(`jsonNode`));
+          for `forLoopI` in 0 .. <`jsonNode`.len: list[`forLoopI`] =`constructorNode`;
+          list
+        )
+
     else:
       # Generic type.
       let obj = getType(typeSym)

tests/stdlib/tjsonmacro.nim

@@ -226,4 +226,24 @@ when isMainModule:
 
     let x = parseJson("""{ "field": 5}""")
     let data = to(x, FooBar)
-    doAssert data.field == 5.0
+    doAssert data.field == 5.0
+
+  block:
+    type
+      BirdColor = object
+        name: string
+        rgb: array[3, float]
+
+    type
+      Bird = object
+        age: int
+        height: float
+        name: string
+        colors: array[2, BirdColor]
+
+    var red = BirdColor(name: "red", rgb: [1.0, 0.0, 0.0])
+    var blue = Birdcolor(name: "blue", rgb: [0.0, 0.0, 1.0])
+    var b = Bird(age: 3, height: 1.734, name: "bardo", colors: [red, blue])
+    let jnode = %b
+    let data = jnode.to(Bird)
+    doAssert data == b