do not generate custom types as empty records, respect the provided g…

…o config and generate it as an alias

backend/apps/automatic-tests/FormsValidator.fs

@@ -58,7 +58,12 @@ let WrongFormStructure() =
   let actual5 = Ballerina.DSL.FormEngine.Runner.runSingle true FormsGenTarget.golang "./input-forms/with errors/wrong form structure 5.json" "./generated-output/models" null null "./input-forms/go-config.json"
   let actual6 = Ballerina.DSL.FormEngine.Runner.runSingle true FormsGenTarget.golang "./input-forms/with errors/wrong form structure 6.json" "./generated-output/models" null null "./input-forms/go-config.json"
   let actual7 = Ballerina.DSL.FormEngine.Runner.runSingle true FormsGenTarget.golang "./input-forms/with errors/wrong form structure 7.json" "./generated-output/models" null null "./input-forms/go-config.json"
-  match actual7 with
-  | Right err -> Errors.Print "wrong form structure" err
-  | _ -> ()  
   Assert.That(actual1.IsRight && actual2.IsRight && actual3.IsRight && actual4.IsRight && actual5.IsRight && actual6.IsRight && actual7.IsRight, Is.EqualTo(true))
+
+[<Test>]
+let WrongPredicateStructure() =
+  let actual1 = Ballerina.DSL.FormEngine.Runner.runSingle true FormsGenTarget.golang "./input-forms/with errors/wrong predicate structure 1.json" "./generated-output/models" null null "./input-forms/go-config.json"
+  match actual1 with
+  | Right err -> Errors.Print "wrong predicate structure" err
+  | _ -> ()  
+  Assert.That(actual1.IsRight, Is.EqualTo(true))

backend/apps/automatic-tests/input-forms/with errors/wrong predicate structure 1.json

@@ -0,0 +1,38 @@
+{
+  "types": {
+    "Person": {
+      "extends": [],
+      "fields": {
+        "Name": "string",
+        "Surname": "string"
+      }
+    }
+  },
+  "forms":{
+    "person": {
+      "type": "Person",
+      "fields": {
+        "Name": {
+          "renderer": "defaultString"
+        },
+        "Surname": {
+          "renderer": "defaultString"
+        }
+      },
+      "tabs": {
+        "main": {
+          "columns": {
+            "main": {
+              "groups": {
+                "main": [
+                  "Name",
+                  "Surname"
+                ]
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+}

backend/libraries/ballerina-core/business rule engine/exprtype/typeCheck.fs

@@ -78,17 +78,16 @@ module TypeCheck =
                     }
                   ) |> sum.All
                 match handlerTypes with
-                | [] -> return ()
+                | [] -> return! sum.Throw(Errors.Singleton $"Error: match-case {e} has no case handlers. One case handler is required for each possible case.")
                 | x::xs ->
-                  do! 
+                  let! ``type`` = 
                     xs |> List.fold (fun unifications expr -> 
                       sum{
                         let! prevExpr,prevUnifications = unifications
                         let! newUnifications = ExprType.Unify Map.empty typeBindings prevExpr expr
                         return expr,newUnifications
                       }) (sum{ return x,UnificationConstraints.Zero() })
-                      |> Sum.map ignore
-                return None,ExprType.PrimitiveType PrimitiveType.BoolType, vars'
+                  return None,``type`` |> fst, vars'
               | t-> 
                 return! sum.Throw(sprintf "Error: unexpected match-case on type %A when typechecking expression %A" t e |> Errors.Singleton)            
             }

backend/libraries/ballerina-core/business rule engine/form engine/codegen/golang.fs

@@ -153,7 +153,7 @@ module Golang =
               })
             )
             yield StringBuilder.One "  }\n"
-            yield StringBuilder.One $$"""return result, {{codegenConfig.StreamNotFoundError.Constructor}}(streamName)"""
+            yield StringBuilder.One $$"""  return result, {{codegenConfig.StreamNotFoundError.Constructor}}(streamName)"""
             yield StringBuilder.One "\n}\n\n"
           }
 
@@ -179,12 +179,21 @@ module Golang =
               })
             )
             yield StringBuilder.One "  }\n"
-            yield StringBuilder.One $$"""return result, {{codegenConfig.StreamNotFoundError.Constructor}}(streamName)"""
+            yield StringBuilder.One $$"""  return result, {{codegenConfig.StreamNotFoundError.Constructor}}(streamName)"""
             yield StringBuilder.One "\n}\n\n"
           }
 
+        let customTypes = codegenConfig.Custom.Keys |> Set.ofSeq
+        let typesToGenerate = ctx.Types |> Map.filter (fun k v -> customTypes |> Set.contains k |> not)
+        let customTypes = 
+          codegenConfig.Custom |> Seq.map (fun t -> 
+            StringBuilder.Many(seq{
+              yield StringBuilder.One "\n"
+              yield StringBuilder.One $"type {t.Key} = {t.Value.GeneratedTypeName}"
+            })
+          )
         let! generatedTypes = state.All(
-          ctx.Types |> Seq.map(fun t -> 
+          typesToGenerate |> Seq.map(fun t -> 
           state{
             match t.Value.Type with
             | ExprType.UnionType cases when cases |> Seq.forall (fun case -> case.Fields.IsUnitType) ->
@@ -293,7 +302,7 @@ module Golang =
             | _ ->
               let! fields = ExprType.GetFields t.Value.Type |> state.OfSum
               let typeStart = $$"""type {{t.Value.TypeId.TypeName}} struct {
-    """
+"""
               let! fieldTypes = state.All(fields |> Seq.map (snd >> ExprType.ToGolangTypeAnnotation) |> List.ofSeq)
               let fieldDeclarations = Many (seq{
                 for fieldType,fieldName in fields |> Seq.map fst |> Seq.zip fieldTypes do
@@ -304,7 +313,7 @@ module Golang =
                   yield StringBuilder.One "\n"
               })
               let typeEnd = $$"""}
-    """
+"""
 
               let consStart = $$"""func New{{t.Value.TypeId.TypeName}}("""
               let consParams = Many (seq{
@@ -315,13 +324,13 @@ module Golang =
                   yield StringBuilder.One ", "
               })
               let consDeclEnd = $$""") {{t.Value.TypeId.TypeName}} {
-      res := new({{t.Value.TypeId.TypeName}})
-    """
+  var res {{t.Value.TypeId.TypeName}}
+"""
 
-              let consBodyEnd = $$"""  return *res
-    }
+              let consBodyEnd = $$"""  return res
+}
 
-    """
+"""
               let consFieldInits = StringBuilder.Many (seq{
                 for fieldType,fieldName in fields |> Seq.map fst |> Seq.zip fieldTypes do
                   yield StringBuilder.One "  res."
@@ -357,6 +366,7 @@ module Golang =
           // yield! entitiesOPSelector "DEFAULT" CrudMethod.Default
           // yield! entitiesOPEnum "DEFAULT" CrudMethod.Default
           yield! generatedTypes
+          yield! customTypes
         })
       } 
       let result = result |> state.WithErrorContext $"...when generating Go code"
@@ -371,6 +381,7 @@ module Golang =
           let imports = if ctx.Apis.Streams |> Map.isEmpty |> not then imports + (codegenConfig.StreamNotFoundError.RequiredImport |> Option.toList |> Set.ofList) else imports
           let imports = imports + (codegenConfig.Guid.RequiredImport |> Option.toList |> Set.ofList)
           let imports = imports + (codegenConfig.Unit.RequiredImport |> Option.toList |> Set.ofList)
+          let imports = imports + (codegenConfig.Custom |> Map.values |> Seq.map (fun v -> v.RequiredImport |> Option.toList) |> List.concat |> Set.ofSeq)
           let heading = StringBuilder.One $$"""package {{packageName}}
 
       import (

todo.md

@@ -64,11 +64,17 @@ Todo (✅/❌)
           ✅ invalid tabs
             ✅ non-existing fields
         ❌ invalid predicates
+          ❌ requires global config, APIs, and launcher 
+          ❌ wrong `root` type
           ❌ non-existing variables
           ❌ non-existing fields
           ❌ mismatched types (`10 == true`)
           ❌ mismatched enum case checks
           ❌ wrong pattern matching
+            ❌ missing case handler
+            ❌ non existing case name
+            ❌ different types of the handlers
+            ❌ same handler types but unexpected type of the whole match
         ❌ invalid launchers
           ❌ non-existing form
           ❌ missing entity API
@@ -84,8 +90,8 @@ Todo (✅/❌)
         ❌ validator
     ❌ the validator is now mature
     ✅ specialize the errors (stream not found, enum not found, etc.)
-    ❌ improve the generated whitespace
-    ❌ the Go type generator is now reasonably mature
+    ✅ improve the generated whitespace
+    ✅ the Go type generator is now reasonably mature
     ❌ add full support for unions, including generation
       ✅ parser
       ✅ validator
@@ -100,12 +106,15 @@ Todo (✅/❌)
         ✅ constructors for the whole thing - assume discriminator, accept specific value
       ❌ add renderer syntax for the selector of a different form depending on the case
         ❌ add renderer syntax for the union container
+        ❌ implement renderer in FE
     ❌ extensions
       ❌ preprocessor plugins
+        ❌ injected at specific times
+        ❌ language generation as parameters
+      ❌ define `include` command
       ❌ add homomorphic forms
       ❌ add multi-field renderers
         ❌ use tuples, meaning it's still just one single field
-      ❌ define `include` command
       ❌ add paginated lists
         ❌ requires changes to the frontend
       ❌ add lazy fields