Elixir: Switch Poison to Jason (OpenAPITools#16061)

* Switch Poison to Jason

* generate-samples.sh

* Finalize Poison -> Jason switch

* parse date-time values to Elixir DateTime
* improve formatting in various places, so there's less changes by `mix
  format` later
* fix Java version in flake.nix

* Use List.delete/2 instead of Enum.reject/2 for performance reasons

* mix format test/*

* Install dialyxir and fix reported issues

* Fix RequestBuilder.decode/2 hardcoded module name

* Update docs

* Revert changes to API spec (HTTP -> HTTPS)

* Revert uneeded change to Elixir code generator

* Use HTTP in Elixir tests

HTTPS doesn't work for folks who setup petstore.swagger.io as described
in docs/faq-contributing.md.

---------

Co-authored-by: Wojciech Piekutowski <[email protected]>

Author: barttenbrinke

docs/generators/elixir.md

@@ -48,7 +48,6 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 <li>AnyType</li>
 <li>Atom</li>
 <li>Boolean</li>
-<li>DateTime</li>
 <li>Decimal</li>
 <li>Float</li>
 <li>Integer</li>

flake.nix

@@ -13,7 +13,7 @@
         devShells.default = pkgs.mkShell
           {
             buildInputs = with pkgs;[
-              jdk8
+              jdk11
               maven
             ];
           };

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ElixirClientCodegen.java

@@ -59,9 +59,10 @@ public class ElixirClientCodegen extends DefaultCodegen {
     String supportedElixirVersion = "1.10";
     List<String> extraApplications = Arrays.asList(":logger");
     List<String> deps = Arrays.asList(
-            "{:tesla, \"~> 1.4\"}",
-            "{:poison, \"~> 3.0\"}",
-            "{:ex_doc, \"~> 0.28\", only: :dev, runtime: false}"
+            "{:tesla, \"~> 1.7\"}",
+            "{:jason, \"~> 1.4\"}",
+            "{:ex_doc, \"~> 0.30\", only: :dev, runtime: false}",
+            "{:dialyxir, \"~> 1.3\", only: [:dev, :test], runtime: false}"
     );
 
     public ElixirClientCodegen() {
@@ -194,7 +195,6 @@ public ElixirClientCodegen() {
                         "AnyType",
                         "Tuple",
                         "PID",
-                        "DateTime",
                         "map()", // This is a workaround, since the DefaultCodeGen uses our elixir TypeSpec datetype to evaluate the primitive
                         "any()"
                 )
@@ -210,7 +210,7 @@ public ElixirClientCodegen() {
         typeMapping.put("string", "String");
         typeMapping.put("byte", "Integer");
         typeMapping.put("boolean", "Boolean");
-        typeMapping.put("Date", "DateTime");
+        typeMapping.put("Date", "Date");
         typeMapping.put("DateTime", "DateTime");
         typeMapping.put("file", "String");
         typeMapping.put("map", "Map");
@@ -575,7 +575,12 @@ public String getTypeDeclaration(Schema p) {
         } else if (ModelUtils.isBooleanSchema(p)) {
             return "boolean()";
         } else if (!StringUtils.isEmpty(p.get$ref())) {
-            return this.moduleName + ".Model." + super.getTypeDeclaration(p) + ".t";
+            switch (super.getTypeDeclaration(p)) {
+                case "String":
+                    return "String.t";
+                default:
+                    return this.moduleName + ".Model." + super.getTypeDeclaration(p) + ".t";
+            }
         } else if (ModelUtils.isFileSchema(p)) {
             return "String.t";
         } else if (ModelUtils.isStringSchema(p)) {
@@ -662,28 +667,23 @@ public String codeMappingKey() {
         }
 
         public String decodedStruct() {
-            // Let Poison decode the entire response into a generic blob
+            // Let Jason decode the entire response into a generic blob
             if (isMap) {
                 return "%{}";
             }
+
             // Primitive return type, don't even try to decode
             if (baseType == null || (containerType == null && primitiveType)) {
                 return "false";
             } else if (isArray && languageSpecificPrimitives().contains(baseType)) {
                 return "[]";
             }
+
             StringBuilder sb = new StringBuilder();
-            if (isArray) {
-                sb.append("[");
-            }
-            sb.append("%");
             sb.append(moduleName);
             sb.append(".Model.");
             sb.append(baseType);
-            sb.append("{}");
-            if (isArray) {
-                sb.append("]");
-            }
+
             return sb.toString();
         }
 
@@ -768,6 +768,24 @@ public void setReplacedPathName(String replacedPathName) {
             this.replacedPathName = replacedPathName;
         }
 
+        private void translateBaseType(StringBuilder returnEntry, String baseType) {
+            switch (baseType) {
+                case "AnyType":
+                    returnEntry.append("any()");
+                    break;
+                case "Boolean":
+                    returnEntry.append("boolean()");
+                    break;
+                case "Float":
+                    returnEntry.append("float()");
+                    break;
+                default:
+                    returnEntry.append(baseType);
+                    returnEntry.append(".t");
+                    break;
+            }
+        }
+
         public String typespec() {
             StringBuilder sb = new StringBuilder("@spec ");
             sb.append(underscore(operationId));
@@ -793,12 +811,7 @@ public String typespec() {
                         returnEntry.append(".Model.");
                     }
 
-                    if (exResponse.baseType.equals("AnyType")) {
-                        returnEntry.append("any()");
-                    }else {
-                        returnEntry.append(exResponse.baseType);
-                        returnEntry.append(".t");
-                    }
+                    translateBaseType(returnEntry, exResponse.baseType);
                 } else {
                     if (exResponse.containerType.equals("array") ||
                             exResponse.containerType.equals("set")) {
@@ -808,12 +821,8 @@ public String typespec() {
                             returnEntry.append(".Model.");
                         }
 
-                        if (exResponse.baseType.equals("AnyType")) {
-                            returnEntry.append("any())");
-                        }else {
-                            returnEntry.append(exResponse.baseType);
-                            returnEntry.append(".t)");
-                        }
+                        translateBaseType(returnEntry, exResponse.baseType);
+                        returnEntry.append(")");
                     } else if (exResponse.containerType.equals("map")) {
                         returnEntry.append("map()");
                     }

modules/openapi-generator/src/main/resources/elixir/connection.ex.mustache

@@ -216,7 +216,7 @@ defmodule {{moduleName}}.Connection do
 
     tesla_options = Application.get_env(:tesla, __MODULE__, [])
     middleware = Keyword.get(tesla_options, :middleware, [])
-    json_engine = Keyword.get(tesla_options, :json, Poison)
+    json_engine = Keyword.get(tesla_options, :json, Jason)
 
     user_agent =
       Keyword.get(

modules/openapi-generator/src/main/resources/elixir/deserializer.ex.mustache

@@ -4,37 +4,81 @@ defmodule {{moduleName}}.Deserializer do
   Helper functions for deserializing responses into models
   """
 
+  @jason_decode_opts [keys: :strings]
+
+  def jason_decode(json) do
+    Jason.decode(json, @jason_decode_opts)
+  end
+
+  def jason_decode(json, module) do
+    json
+    |> jason_decode()
+    |> case do
+      {:ok, decoded} -> {:ok, to_struct(decoded, module)}
+      {:error, _} = error -> error
+    end
+  end
+
   @doc """
   Update the provided model with a deserialization of a nested value
   """
-  @spec deserialize(struct(), :atom, :atom, struct(), keyword()) :: struct()
-  def deserialize(model, field, :list, mod, options) do
+  @spec deserialize(struct(), atom(), :date | :datetime | :list | :map | :struct, module()) ::
+          struct()
+  def deserialize(model, field, :list, module) do
     model
-    |> Map.update!(field, &(Poison.Decode.decode(&1, Keyword.merge(options, [as: [struct(mod)]]))))
+    |> Map.update!(field, fn
+      nil ->
+        nil
+
+      list ->
+        Enum.map(list, &to_struct(&1, module))
+    end)
   end
 
-  def deserialize(model, field, :struct, mod, options) do
+  def deserialize(model, field, :struct, module) do
     model
-    |> Map.update!(field, &(Poison.Decode.decode(&1, Keyword.merge(options, [as: struct(mod)]))))
+    |> Map.update!(field, fn
+      nil ->
+        nil
+
+      value ->
+        to_struct(value, module)
+    end)
   end
 
-  def deserialize(model, field, :map, mod, options) do
+  def deserialize(model, field, :map, module) do
     maybe_transform_map = fn
       nil ->
         nil
 
       existing_value ->
         Map.new(existing_value, fn
-          {key, val} ->
-            {key, Poison.Decode.decode(val, Keyword.merge(options, as: struct(mod)))}
+          {key, value} ->
+            {key, to_struct(value, module)}
         end)
     end
 
     Map.update!(model, field, maybe_transform_map)
   end
 
-  def deserialize(model, field, :date, _, _options) do
+  def deserialize(model, field, :date, _) do
+    value = Map.get(model, field)
+
+    case is_binary(value) do
+      true ->
+        case Date.from_iso8601(value) do
+          {:ok, date} -> Map.put(model, field, date)
+          _ -> model
+        end
+
+      false ->
+        model
+    end
+  end
+
+  def deserialize(model, field, :datetime, _) do
     value = Map.get(model, field)
+
     case is_binary(value) do
       true ->
         case DateTime.from_iso8601(value) do
@@ -46,4 +90,23 @@ defmodule {{moduleName}}.Deserializer do
         model
     end
   end
+
+  defp to_struct(map_or_list, module)
+  defp to_struct(nil, _), do: nil
+
+  defp to_struct(list, module) when is_list(list) and is_atom(module) do
+    Enum.map(list, &to_struct(&1, module))
+  end
+
+  defp to_struct(map, module) when is_map(map) and is_atom(module) do
+    model = struct(module)
+
+    model
+    |> Map.keys()
+    |> List.delete(:__struct__)
+    |> Enum.reduce(model, fn field, acc ->
+      Map.replace(acc, field, Map.get(map, Atom.to_string(field)))
+    end)
+    |> module.decode()
+  end
 end

modules/openapi-generator/src/main/resources/elixir/mix.exs.mustache

@@ -9,7 +9,9 @@ defmodule {{moduleName}}.Mixfile do
       build_embedded: Mix.env() == :prod,
       start_permanent: Mix.env() == :prod,
       package: package(),
-      description: "{{appDescription}}",
+      description: """
+      {{appDescription}}
+      """,
       deps: deps()
     ]
   end

modules/openapi-generator/src/main/resources/elixir/model.mustache

@@ -4,7 +4,7 @@
   {{&description}}
   """
 
-  @derive [Poison.Encoder]
+  @derive Jason.Encoder
   defstruct [
     {{#vars}}{{#atom}}{{&baseName}}{{/atom}}{{^-last}},
     {{/-last}}{{/vars}}
@@ -14,22 +14,21 @@
     {{#vars}}{{#atom}}{{&baseName}}{{/atom}} => {{{datatype}}}{{#isNullable}} | nil{{/isNullable}}{{^isNullable}}{{^required}} | nil{{/required}}{{/isNullable}}{{^-last}},
     {{/-last}}{{/vars}}
   }
-end
 
-defimpl Poison.Decoder, for: {{&moduleName}}.Model.{{&classname}} do
 {{#hasComplexVars}}
-  import {{&moduleName}}.Deserializer
-  def decode(value, options) do
+  alias {{&moduleName}}.Deserializer
+
+  def decode(value) do
     value
     {{#vars}}
     {{^isPrimitiveType}}
-    {{#baseType}}|> deserialize({{#atom}}{{&baseName}}{{/atom}}, {{#isArray}}:list, {{&moduleName}}.Model.{{{items.baseType}}}{{/isArray}}{{#isMap}}:map, {{&moduleName}}.Model.{{{items.baseType}}}{{/isMap}}{{#isDate}}:date, nil{{/isDate}}{{#isDateTime}}:date, nil{{/isDateTime}}{{^isDate}}{{^isDateTime}}{{^isMap}}{{^isArray}}:struct, {{moduleName}}.Model.{{baseType}}{{/isArray}}{{/isMap}}{{/isDateTime}}{{/isDate}}, options)
+    {{#baseType}} |> Deserializer.deserialize({{#atom}}{{&baseName}}{{/atom}}, {{#isArray}}:list, {{&moduleName}}.Model.{{{items.baseType}}}{{/isArray}}{{#isMap}}:map, {{&moduleName}}.Model.{{{items.baseType}}}{{/isMap}}{{#isDate}}:date, nil{{/isDate}}{{#isDateTime}}:datetime, nil{{/isDateTime}}{{^isDate}}{{^isDateTime}}{{^isMap}}{{^isArray}}:struct, {{moduleName}}.Model.{{baseType}}{{/isArray}}{{/isMap}}{{/isDateTime}}{{/isDate}})
     {{/baseType}}
     {{/isPrimitiveType}}
     {{/vars}}
 {{/hasComplexVars}}
 {{^hasComplexVars}}
-  def decode(value, _options) do
+  def decode(value) do
     value
 {{/hasComplexVars}}
   end

modules/openapi-generator/src/main/resources/elixir/request_builder.ex.mustache

@@ -94,7 +94,7 @@ defmodule {{moduleName}}.RequestBuilder do
       Tesla.Multipart.add_field(
         multipart,
         key,
-        Poison.encode!(value),
+        Jason.encode!(value),
         headers: [{:"Content-Type", "application/json"}]
       )
     end)
@@ -146,8 +146,8 @@ defmodule {{moduleName}}.RequestBuilder do
     Map.put_new(request, :body, "")
   end
 
-  @type status_code :: 100..599
-  @type response_mapping :: [{status_code, struct() | false}]
+  @type status_code :: :default | 100..599
+  @type response_mapping :: [{status_code, false | %{} | module()}]
 
   @doc """
   Evaluate the response from a Tesla request.
@@ -185,5 +185,11 @@ defmodule {{moduleName}}.RequestBuilder do
 
   defp decode(%Tesla.Env{} = env, false), do: {:ok, env}
 
-  defp decode(%Tesla.Env{body: body}, struct), do: Poison.decode(body, as: struct)
+  defp decode(%Tesla.Env{body: body}, %{}) do
+    {{moduleName}}.Deserializer.jason_decode(body)
+  end
+
+  defp decode(%Tesla.Env{body: body}, module) do
+    {{moduleName}}.Deserializer.jason_decode(body, module)
+  end
 end

samples/client/petstore/elixir/lib/openapi_petstore/api/another_fake.ex

@@ -36,7 +36,7 @@ defmodule OpenapiPetstore.Api.AnotherFake do
     connection
     |> Connection.request(request)
     |> evaluate_response([
-      {200, %OpenapiPetstore.Model.Client{}}
+      {200, OpenapiPetstore.Model.Client}
     ])
   end
 end

samples/client/petstore/elixir/lib/openapi_petstore/api/default.ex

@@ -32,7 +32,7 @@ defmodule OpenapiPetstore.Api.Default do
     connection
     |> Connection.request(request)
     |> evaluate_response([
-      {:default, %OpenapiPetstore.Model.FooGetDefaultResponse{}}
+      {:default, OpenapiPetstore.Model.FooGetDefaultResponse}
     ])
   end
 end