Fix issue with int64map json code generation

src/Generator/Message.elm

@@ -622,11 +622,8 @@ fieldTypeToEncoder cardinality fieldType =
 fieldTypeToJsonMapKey : FieldType -> C.Expression
 fieldTypeToJsonMapKey fieldType =
     case fieldType of
-        Primitive Prim_String _ ->
-            Meta.Basics.identity
-
-        Primitive (Prim_Int32 _) _ ->
-            C.fqFun [ "String" ] "fromInt"
+        Primitive primitive _ ->
+            Meta.JsonEncode.primitiveToMapKey primitive
 
         _ ->
             C.string "ERROR: This should not happen. Map keys are supposed to be primitive only."

src/Meta/JsonEncode.elm

@@ -1,7 +1,6 @@
 module Meta.JsonEncode exposing (..)
 
 import Elm.CodeGen as C exposing (Expression, ModuleName, TypeAnnotation)
-import Json.Encode
 import Model exposing (IntFlavor(..), Primitive(..))
 
 
@@ -70,7 +69,7 @@ forPrimitive prim =
             int64
 
         Prim_Int64 UInt ->
-            int64
+            uint64
 
         Prim_Int64 Fixed ->
             int64
@@ -94,6 +93,55 @@ forPrimitive prim =
             float
 
 
+primitiveToMapKey : Primitive -> Expression
+primitiveToMapKey prim =
+    case prim of
+        Prim_Int32 Int_ ->
+            int32_toMapKey
+
+        Prim_Int32 SInt ->
+            int32_toMapKey
+
+        Prim_Int32 UInt ->
+            int32_toMapKey
+
+        Prim_Int32 Fixed ->
+            int32_toMapKey
+
+        Prim_Int32 SFixed ->
+            int32_toMapKey
+
+        Prim_Int64 Int_ ->
+            int64_toMapKey
+
+        Prim_Int64 SInt ->
+            int64_toMapKey
+
+        Prim_Int64 UInt ->
+            uint64_toMapKey
+
+        Prim_Int64 Fixed ->
+            int64_toMapKey
+
+        Prim_Int64 SFixed ->
+            int64_toMapKey
+
+        Prim_String ->
+            C.fun "identity"
+
+        Prim_Bool ->
+            C.string "ERROR: Bool is not a valid key for a protobuf map!"
+
+        Prim_Float ->
+            C.string "ERROR: Float is not a valid key for a protobuf map!"
+
+        Prim_Bytes ->
+            C.string "ERROR: Bytes is not a valid key for a protobuf map!"
+
+        Prim_Double ->
+            C.string "ERROR: Double is not a valid key for a protobuf map!"
+
+
 int32 : Expression
 int32 =
     C.fqFun moduleName "int"
@@ -116,9 +164,40 @@ bytes =
 
 int64 : Expression
 int64 =
-    C.parens <| C.applyBinOp (C.fqFun [ "Protobuf", "Utils", "Int64" ] "toSignedString") C.composer string
+    C.parens <| C.applyBinOp int64_toString C.composer string
+
+
+int32_toMapKey : Expression
+int32_toMapKey =
+    C.fqFun [ "String" ] "fromInt"
+
+
+int64_toMapKey : Expression
+int64_toMapKey =
+    C.parens
+        (C.lambda [ C.tuplePattern [ C.varPattern "upper", C.varPattern "lower" ] ] <|
+            C.pipe (C.apply [ C.fqFun [ "Protobuf", "Types", "Int64" ] "fromInts", C.val "upper", C.val "lower" ]) [ int64_toString ]
+        )
+
+
+uint64_toMapKey : Expression
+uint64_toMapKey =
+    C.parens
+        (C.lambda [ C.tuplePattern [ C.varPattern "upper", C.varPattern "lower" ] ] <|
+            C.pipe (C.apply [ C.fqFun [ "Protobuf", "Types", "Int64" ] "fromInts", C.val "upper", C.val "lower" ]) [ uint64_toString ]
+        )
+
+
+int64_toString : Expression
+int64_toString =
+    C.fqFun [ "Protobuf", "Utils", "Int64" ] "toSignedString"
+
+
+uint64_toString : Expression
+uint64_toString =
+    C.fqFun [ "Protobuf", "Utils", "Int64" ] "toUnsignedString"
 
 
 uint64 : Expression
 uint64 =
-    C.parens <| C.applyBinOp (C.fqFun [ "Protobuf", "Utils", "Int64" ] "toUnsignedString") C.composer string
+    C.parens <| C.applyBinOp uint64_toString C.composer string