Add support for enum schemas and properties to the rust generator

Also:
* Skip serializing a field with serde if it's optional and empty
* Fix borrow checker error when using &std::path::Path (should be std::path::PathBuf)
* Add script to generate sample with rust-reqwest
* Regenerate petstore sample for both rust targets
* Remove go code from RDME.md

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

@@ -122,8 +122,7 @@ public RustClientCodegen() {
         // TODO(bcourtine): review file mapping.
         // I tried to map as "std::io::File", but Reqwest multipart file requires a "AsRef<Path>" param.
         // Getting a file from a Path is simple, but the opposite is difficult. So I map as "std::path::Path".
-        // Reference is required here because Path does not implement the "Sized" trait.
-        typeMapping.put("file", "&std::path::Path");
+        typeMapping.put("file", "std::path::PathBuf");
         typeMapping.put("binary", "::models::File");
         typeMapping.put("ByteArray", "String");
         typeMapping.put("object", "Value");
@@ -150,6 +149,12 @@ public RustClientCodegen() {
         setLibrary(HYPER_LIBRARY);
     }
 
+    @Override
+    public Map<String, Object> postProcessModels(Map<String, Object> objs) {
+        // process enum in models
+        return postProcessModelsEnum(objs);
+    }
+
     @Override
     public void processOpts() {
         super.processOpts();
@@ -487,25 +492,25 @@ public String toEnumDefaultValue(String value, String datatype) {
     @Override
     public String toEnumVarName(String name, String datatype) {
         if (name.length() == 0) {
-            return "EMPTY";
+            return "Empty";
         }
 
         // number
         if ("int".equals(datatype) || "double".equals(datatype) || "float".equals(datatype)) {
             String varName = name;
-            varName = varName.replaceAll("-", "MINUS_");
-            varName = varName.replaceAll("\\+", "PLUS_");
-            varName = varName.replaceAll("\\.", "_DOT_");
+            varName = varName.replaceAll("-", "Minus");
+            varName = varName.replaceAll("\\+", "Plus");
+            varName = varName.replaceAll("\\.", "Dot");
             return varName;
         }
 
         // for symbol, e.g. $, #
         if (getSymbolName(name) != null) {
-            return getSymbolName(name).toUpperCase(Locale.ROOT);
+            return getSymbolName(name);
         }
 
         // string
-        String enumName = sanitizeName(underscore(name).toUpperCase(Locale.ROOT));
+        String enumName = sanitizeName(camelize(name));
         enumName = enumName.replaceFirst("^_", "");
         enumName = enumName.replaceFirst("_$", "");
 
@@ -518,7 +523,9 @@ public String toEnumVarName(String name, String datatype) {
 
     @Override
     public String toEnumName(CodegenProperty property) {
-        String enumName = underscore(toModelName(property.name)).toUpperCase(Locale.ROOT);
+        // camelize the enum name
+        // phone_number => PhoneNumber
+        String enumName = camelize(toModelName(property.name));
 
         // remove [] for array or map of enum
         enumName = enumName.replace("[]", "");

modules/openapi-generator/src/main/resources/rust/README.mustache

@@ -20,10 +20,10 @@ For more information, please visit [{{{infoUrl}}}]({{{infoUrl}}})
 
 ## Installation
 
-Put the package under your project folder and add the following in import:
+Put the package under your project folder and add the following to `Cargo.toml` under `[dependencies]`:
 
 ```
-    "./{{{packageName}}}"
+    openapi = { path = "./generated" }
 ```
 
 ## Documentation for API Endpoints
@@ -40,69 +40,12 @@ Class | Method | HTTP request | Description
 {{#models}}{{#model}} - [{{{classname}}}]({{{modelDocPath}}}{{{classname}}}.md)
 {{/model}}{{/models}}
 
-## Documentation For Authorization
-
-{{^authMethods}} Endpoints do not require authorization.
-{{/authMethods}}{{#authMethods}}{{#last}} Authentication schemes defined for the API:{{/last}}{{/authMethods}}
-{{#authMethods}}
-
-## {{{name}}}
-
-{{#isApiKey}}- **Type**: API key
-
-Example
-```
-    auth := context.WithValue(context.TODO(), sw.ContextAPIKey, sw.APIKey{
-      Key: "APIKEY",
-      Prefix: "Bearer", // Omit if not necessary.
-    })
-    r, err := client.Service.Operation(auth, args)
-```
-{{/isApiKey}}
-{{#isBasic}}- **Type**: HTTP basic authentication
-
-Example
-
-```
-    auth := context.WithValue(context.TODO(), sw.ContextBasicAuth, sw.BasicAuth{
-        UserName: "username",
-        Password: "password",
-    })
-    r, err := client.Service.Operation(auth, args)
-```
-
-{{/isBasic}}
-{{#isOAuth}}
-
-- **Type**: OAuth
-- **Flow**: {{{flow}}}
-- **Authorization URL**: {{{authorizationUrl}}}
-- **Scopes**: {{^scopes}}N/A{{/scopes}}
-{{#scopes}} - **{{{scope}}}**: {{{description}}}
-{{/scopes}}
-
-Example
-
-```
-    auth := context.WithValue(context.TODO(), sw.ContextAccessToken, "ACCESSTOKENSTRING")
-    r, err := client.Service.Operation(auth, args)
-```
-
-Or via OAuth2 module to automatically refresh tokens and perform user authentication.
+To get access to the crate's generated documentation, use:
 
 ```
-    import "golang.org/x/oauth2"
-
-    / .. Perform OAuth2 round trip request and obtain a token .. //
-
-    tokenSource := oauth2cfg.TokenSource(createContext(httpClient), &token)
-    auth := context.WithValue(oauth2.NoContext, sw.ContextOAuth2, tokenSource)
-    r, err := client.Service.Operation(auth, args)
+cargo doc --open
 ```
 
-{{/isOAuth}}
-{{/authMethods}}
-
 ## Author
 
 {{#apiInfo}}{{#apis}}{{^hasMore}}{{{infoEmail}}}

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

@@ -8,13 +8,28 @@
 #[allow(unused_imports)]
 use serde_json::Value;
 
+{{!-- for enum schemas --}}
+{{#isEnum}}
+/// {{{description}}}
+#[derive(Debug, Serialize, Deserialize)]
+pub enum {{classname}} {
+{{#allowableValues}}
+{{#enumVars}}
+    #[serde(rename = "{{{value}}}")]
+    {{name}},
+{{/enumVars}}{{/allowableValues}}
+}
+{{/isEnum}}
+
+{{!-- for non-enum schemas --}}
+{{^isEnum}}
 #[derive(Debug, Serialize, Deserialize)]
 pub struct {{{classname}}} {
 {{#vars}}
     {{#description}}
     /// {{{description}}}
     {{/description}}
-    #[serde(rename = "{{{baseName}}}")]
+    #[serde(rename = "{{{baseName}}}"{{^required}}, skip_serializing_if="Option::is_none"{{/required}})]
     pub {{{name}}}: {{#required}}{{#isNullable}}Option<{{/isNullable}}{{/required}}{{^required}}Option<{{/required}}{{{dataType}}}{{#required}}{{#isNullable}}>{{/isNullable}}{{/required}}{{^required}}>{{/required}},
 {{/vars}}
 }
@@ -31,16 +46,23 @@ impl {{{classname}}} {
         }
     }
 }
+{{/isEnum}}
+
+{{!-- for properties that are of enum type --}}
+{{#vars}}
 {{#isEnum}}
-// TODO enum
-// List of {{{name}}}
-//const (
-//    {{#allowableValues}}
-//    {{#enumVars}}
-//    {{{name}}} {{{classname}}} = "{{{value}}}"
-//    {{/enumVars}}
-//    {{/allowableValues}}
-//)
+/// {{{description}}}
+#[derive(Debug, Serialize, Deserialize)]
+pub enum {{enumName}} {
+{{#allowableValues}}
+{{#enumVars}}
+    #[serde(rename = "{{{value}}}")]
+    {{name}},
+{{/enumVars}}
+{{/allowableValues}}
+}
 {{/isEnum}}
+{{/vars}}
+
 {{/model}}
 {{/models}}

samples/client/petstore/rust-reqwest/README.md

@@ -3,16 +3,19 @@
 This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
 
 ## Overview
+
 This API client was generated by the [OpenAPI Generator](https://openapi-generator.tech) project.  By using the [openapi-spec](https://openapis.org) from a remote server, you can easily generate an API client.
 
 - API version: 1.0.0
 - Package version: 1.0.0
 - Build package: org.openapitools.codegen.languages.RustClientCodegen
 
 ## Installation
-Put the package under your project folder and add the following in import:
+
+Put the package under your project folder and add the following to `Cargo.toml` under `[dependencies]`:
+
 ```
-    "./petstore_client"
+    openapi = { path = "./generated" }
 ```
 
 ## Documentation for API Endpoints
@@ -53,42 +56,10 @@ Class | Method | HTTP request | Description
  - [User](docs/User.md)
 
 
-## Documentation For Authorization
+To get access to the crate's generated documentation, use:
 
-## api_key
-- **Type**: API key 
-
-Example
-```
-	auth := context.WithValue(context.TODO(), sw.ContextAPIKey, sw.APIKey{
-		Key: "APIKEY",
-		Prefix: "Bearer", // Omit if not necessary.
-	})
-    r, err := client.Service.Operation(auth, args)
-```
-## petstore_auth
-- **Type**: OAuth
-- **Flow**: implicit
-- **Authorization URL**: http://petstore.swagger.io/api/oauth/dialog
-- **Scopes**: 
- - **write:pets**: modify pets in your account
- - **read:pets**: read your pets
-
-Example
 ```
-	auth := context.WithValue(context.TODO(), sw.ContextAccessToken, "ACCESSTOKENSTRING")
-    r, err := client.Service.Operation(auth, args)
-```
-
-Or via OAuth2 module to automatically refresh tokens and perform user authentication.
-```
-	import 	"golang.org/x/oauth2"
-
-    / .. Perform OAuth2 round trip request and obtain a token .. //
-
-    tokenSource := oauth2cfg.TokenSource(createContext(httpClient), &token)
-	auth := context.WithValue(oauth2.NoContext, sw.ContextOAuth2, tokenSource)
-    r, err := client.Service.Operation(auth, args)
+cargo doc --open
 ```
 
 ## Author

samples/client/petstore/rust-reqwest/docs/ApiResponse.md

@@ -1,6 +1,7 @@
 # ApiResponse
 
 ## Properties
+
 Name | Type | Description | Notes
 ------------ | ------------- | ------------- | -------------
 **code** | **i32** |  | [optional] 

samples/client/petstore/rust-reqwest/docs/Category.md

@@ -1,6 +1,7 @@
 # Category
 
 ## Properties
+
 Name | Type | Description | Notes
 ------------ | ------------- | ------------- | -------------
 **id** | **i64** |  | [optional] 

samples/client/petstore/rust-reqwest/docs/Order.md

@@ -1,6 +1,7 @@
 # Order
 
 ## Properties
+
 Name | Type | Description | Notes
 ------------ | ------------- | ------------- | -------------
 **id** | **i64** |  | [optional] 

samples/client/petstore/rust-reqwest/docs/Pet.md

@@ -1,6 +1,7 @@
 # Pet
 
 ## Properties
+
 Name | Type | Description | Notes
 ------------ | ------------- | ------------- | -------------
 **id** | **i64** |  | [optional]