Merge pull request #43 from SolitudeSF/discriminant

Don't require discriminant field to be present in object variants

Author: treeform

src/jsony.nim

@@ -405,7 +405,7 @@ proc parseHook*[T: object|ref object](s: string, i: var int, v: var T) =
     elif compiles(new(v)):
       new(v)
   else:
-    # Look for the discriminatorFieldName, then parse as normal object.
+    # Try looking for the discriminatorFieldName, then parse as normal object.
     eatSpace(s, i)
     var saveI = i
     while i < s.len:
@@ -422,9 +422,14 @@ proc parseHook*[T: object|ref object](s: string, i: var int, v: var T) =
           newHook(v)
         break
       skipValue(s, i)
-      if i < s.len and s[i] == '}':
-        error("No discriminator field.", i)
-      eatChar(s, i, ',')
+      if i < s.len and s[i] != '}':
+        eatChar(s, i, ',')
+      else:
+        when compiles(newHook(v)):
+          newHook(v)
+        elif compiles(new(v)):
+          new(v)
+        break
     i = saveI
   parseObjectInner(s, i, v)
   eatChar(s, i, '}')

tests/test_objects.nim

@@ -201,9 +201,9 @@ block:
 
   block:
     # Test discriminator field name not being there.
-    doAssertRaises JsonError:
-      let
-        a = """{"active":true,"floatVal":3.14}""".fromJson(RefNode)
+    let
+      a = """{"active":true,"intVal":42}""".fromJson(RefNode)
+    doAssert a.kind == nkInt
 
   block:
     var nodeNum = ValueNode(kind: nkFloat, active: true, floatVal: 3.14)
@@ -225,9 +225,9 @@ block:
 
   block:
     # Test discriminator field name not being there.
-    doAssertRaises JsonError:
-      let
-        a = """{"active":true,"floatVal":3.14}""".fromJson(ValueNode)
+    let
+      a = """{"active":true,"intVal":42}""".fromJson(ValueNode)
+    doAssert a.kind == nkInt
 
 type
     NodeNumKind = enum  # the different node types
@@ -249,24 +249,28 @@ proc renameHook*(v: var RefNode|ValueNode, fieldName: var string) =
   if fieldName == "type":
     fieldName = "kind"
 
-# Test renameHook and discriminator Field Name not being first.
+# Test renameHook and discriminator Field Name not being first/missing.
 block:
   let
     a = """{"active":true,"type":"nkFloat","floatVal":3.14}""".fromJson(RefNode)
     b = """{"floatVal":3.14,"active":true,"type":"nkFloat"}""".fromJson(RefNode)
     c = """{"type":"nkFloat","floatVal":3.14,"active":true}""".fromJson(RefNode)
+    d = """{"active":true,"intVal":42}""".fromJson(RefNode)
   doAssert a.kind == nkFloat
   doAssert b.kind == nkFloat
   doAssert c.kind == nkFloat
+  doAssert d.kind == nkInt
 
 block:
   let
     a = """{"active":true,"type":"nkFloat","floatVal":3.14}""".fromJson(ValueNode)
     b = """{"floatVal":3.14,"active":true,"type":"nkFloat"}""".fromJson(ValueNode)
     c = """{"type":"nkFloat","floatVal":3.14,"active":true}""".fromJson(ValueNode)
+    d = """{"active":true,"intVal":42}""".fromJson(ValueNode)
   doAssert a.kind == nkFloat
   doAssert b.kind == nkFloat
   doAssert c.kind == nkFloat
+  doAssert d.kind == nkInt
 
 
 # test https://forum.nim-lang.org/t/7619