fix(codegen): implement type-driven form encoding across SDKs (#1674)

Transition from explicitly assigning Content-Type headers inside
generated methods to using native language Wrapper Types (e.g.
URLSearchParams, FormValues) that the Runtime Library automatically
deserializes for application/x-www-form-urlencoded behaviors.

Fixes #1673

Author: popmonkey

csharp/rtl/Constants.cs

@@ -80,4 +80,11 @@ public interface IValues : IDictionary<string, object>
     public class Values : Dictionary<string, object>, IValues
     {
     }
+
+    /// <summary>
+    /// Type for explicitly specifying url-encoded form values
+    /// </summary>
+    public class FormValues : Values
+    {
+    }
 }

csharp/rtl/Transport.cs

@@ -234,6 +234,18 @@ public async Task<IRawResponse> RawRequest(
                         Encoding.UTF8,
                         "application/x-www-form-urlencoded");
                 }
+                else if (body is FormValues)
+                {
+                    var dict = ((FormValues)body)
+                        .Where(k => k.Value != null)
+                        .ToDictionary(k => k.Key, k =>
+                        {
+                            if (k.Value is DateTime dt) return dt.ToString("o");
+                            if (k.Value is string || k.Value.GetType().IsPrimitive) return k.Value.ToString();
+                            return JsonSerializer.Serialize(k.Value, new JsonSerializerOptions { IgnoreNullValues = true });
+                        });
+                    request.Content = new FormUrlEncodedContent(dict);
+                }
                 else
                 {
                     request.Content =

go/rtl/auth.go

@@ -87,6 +87,9 @@ func NewAuthSessionWithTransport(config ApiSettings, transport http.RoundTripper
 	}
 }
 
+// Values is a map alias used for form urlencoded bodies
+type Values map[string]interface{}
+
 func (s *AuthSession) Do(result interface{}, method, ver, path string, reqPars map[string]interface{}, body interface{}, options *ApiSettings) error {
 
 	// prepare URL
@@ -97,29 +100,36 @@ func (s *AuthSession) Do(result interface{}, method, ver, path string, reqPars m
 
 	// serialize body to string and determine request's Content-Type header
 	if body != nil {
-		// get the `body`'s type
-		kind := reflect.TypeOf(body).Kind()
-		value := reflect.ValueOf(body)
-
-		// check if it is pointer
-		if kind == reflect.Ptr {
-			// if so find the type it points to
-			kind = reflect.ValueOf(body).Elem().Kind()
-			value = reflect.ValueOf(body).Elem()
-		}
-
-		if kind == reflect.String {
-			contentTypeHeader = "text/plain"
-			bodyString = fmt.Sprintf("%v", value)
+		if v, ok := body.(Values); ok {
+			contentTypeHeader = "application/x-www-form-urlencoded"
+			u := &url.URL{}
+			setQuery(u, map[string]interface{}(v))
+			bodyString = u.RawQuery
 		} else {
-			contentTypeHeader = "application/json"
-			serializedBody, err := json.Marshal(body)
-
-			if err != nil {
-				_, _ = fmt.Fprintf(os.Stderr, "error serializing body: %v", err)
+			// get the `body`'s type
+			kind := reflect.TypeOf(body).Kind()
+			value := reflect.ValueOf(body)
+
+			// check if it is pointer
+			if kind == reflect.Ptr {
+				// if so find the type it points to
+				kind = reflect.ValueOf(body).Elem().Kind()
+				value = reflect.ValueOf(body).Elem()
 			}
 
-			bodyString = string(serializedBody)
+			if kind == reflect.String {
+				contentTypeHeader = "text/plain"
+				bodyString = fmt.Sprintf("%v", value)
+			} else {
+				contentTypeHeader = "application/json"
+				serializedBody, err := json.Marshal(body)
+
+				if err != nil {
+					_, _ = fmt.Fprintf(os.Stderr, "error serializing body: %v", err)
+				}
+
+				bodyString = string(serializedBody)
+			}
 		}
 	}
 

kotlin/src/main/com/looker/rtl/Transport.kt

@@ -217,8 +217,10 @@ fun encodeParam(value: Any?): String {
             value.toOffsetDateTime().format(utcFormat)
         } else if (value is Date) {
             value.toInstant().atZone(ZoneOffset.UTC).format(utcFormat)
-        } else {
+        } else if (value is String || value is Number || value is Boolean) {
             "$value"
+        } else {
+            GSON.toJson(value)
         }
     try {
         val decoded = URLDecoder.decode(encoded, utf8)

packages/sdk-codegen/src/codeGen.ts

@@ -1317,12 +1317,13 @@ export abstract class CodeGen implements ICodeGen {
   assignFormArgs(
     method: IMethod,
     body: string,
-    query: string
-  ): { body: string; query: string } {
+    query: string,
+    options: string
+  ): { body: string; query: string; options: string } {
     if (method.isFormUrlEncoded) {
-      return { body: query, query: this.nullStr };
+      return { body: query, query: this.nullStr, options };
     }
-    return { body, query };
+    return { body, query, options };
   }
 
   // build the http argument list from back to front, so trailing undefined arguments
@@ -1338,9 +1339,13 @@ export abstract class CodeGen implements ICodeGen {
     result = this.argFill(result, this.argGroup(indent, method.headerArgs));
     let body = method.bodyArg ? method.bodyArg : this.nullStr;
     let query = this.argGroup(indent, method.queryArgs);
-    const formArgs = this.assignFormArgs(method, body, query);
+    // Add 'options' since it might be modified for form encoding
+    let options = this.nullStr;
+    const formArgs = this.assignFormArgs(method, body, query, options);
     body = formArgs.body;
     query = formArgs.query;
+    options = formArgs.options;
+    result = this.argFill(result, options);
     result = this.argFill(result, body);
     result = this.argFill(result, query);
     return result;

packages/sdk-codegen/src/csharp.gen.ts

@@ -341,15 +341,30 @@ namespace Looker.SDK.API${this.apiRef}
       : this.nullStr;
   }
 
+  assignFormArgs(
+    method: IMethod,
+    body: string,
+    query: string,
+    options: string
+  ): { body: string; query: string; options: string } {
+    if (method.isFormUrlEncoded) {
+      // CSharp uses "new FormValues { ... }" to trigger RTL-level URL encoding.
+      query = query.replace(/new Values \{/g, 'new FormValues {');
+      return { body: query, query: this.nullStr, options };
+    }
+    return { body, query, options };
+  }
+
   httpArgs(indent: string, method: IMethod) {
-    let result = this.argFill('', 'options');
-    // result = this.argFill(result, this.argGroup(indent, method.cookieArgs))
-    // result = this.argFill(result, this.argGroup(indent, method.headerArgs))
+    let options = 'options';
     let body = method.bodyArg ? method.bodyArg : this.nullStr;
     let query = this.argGroup(indent, method.queryArgs);
-    const formArgs = this.assignFormArgs(method, body, query);
+    const formArgs = this.assignFormArgs(method, body, query, options);
     body = formArgs.body;
     query = formArgs.query;
+    options = formArgs.options;
+
+    let result = this.argFill('', options);
     result = this.argFill(result, body);
     result = this.argFill(result, query);
     return result;

packages/sdk-codegen/src/go.gen.ts

@@ -284,21 +284,35 @@ export class GoGen extends CodeGen {
     // add options at the end of the request calls. this will cause all other arguments to be
     // filled in but there's no way to avoid this for passing in the last optional parameter.
     // Fortunately, this code bloat is minimal and also hidden from the consumer.
-    let result = this.argFill('', 'options');
-    // let result = this.argFill('', this.argGroup(indent, method.cookieArgs, request))
-    // result = this.argFill(result, this.argGroup(indent, method.headerArgs, request))
+    let options = 'options';
     let body = method.bodyArg
       ? this.accessor(method.bodyArg, request)
       : this.nullStr;
     let query = this.argGroup(indent, method.queryArgs, request);
-    const formArgs = this.assignFormArgs(method, body, query);
+    const formArgs = this.assignFormArgs(method, body, query, options);
     body = formArgs.body;
     query = formArgs.query;
+    options = formArgs.options;
+
+    let result = this.argFill('', options);
     result = this.argFill(result, body);
     result = this.argFill(result, query);
     return result;
   }
 
+  assignFormArgs(
+    method: IMethod,
+    body: string,
+    query: string,
+    options: string
+  ): { body: string; query: string; options: string } {
+    if (method.isFormUrlEncoded) {
+      body = query.replace('map[string]interface{}', 'rtl.Values');
+      query = this.nullStr;
+    }
+    return { body, query, options };
+  }
+
   argGroup(_indent: string, args: Arg[], prefix?: string) {
     if (!args || args.length === 0) return this.nullStr;
     const hash: string[] = [];

packages/sdk-codegen/src/kotlin.gen.ts

@@ -458,12 +458,16 @@ ${props.join(this.propDelimiter)}
   assignFormArgs(
     method: IMethod,
     body: string,
-    query: string
-  ): { body: string; query: string } {
-    const result = super.assignFormArgs(method, body, query);
+    query: string,
+    options: string
+  ): { body: string; query: string; options: string } {
+    const result = super.assignFormArgs(method, body, query, options);
     if (result.query === this.nullStr) {
       result.query = 'mapOf()';
     }
+    if (method.isFormUrlEncoded) {
+      result.body = `encodeValues(${result.body})`;
+    }
     return result;
   }
 
@@ -483,11 +487,13 @@ ${props.join(this.propDelimiter)}
     // let result = this.argFill('', 'options')
     // let result = this.argFill('', this.argGroup(indent, method.cookieArgs, request))
     // result = this.argFill(result, this.argGroup(indent, method.headerArgs, request))
+    let options = 'options';
     let body = method.bodyArg ? `${request}${method.bodyArg}` : this.nullStr;
     let query = this.argGroup(indent, method.queryArgs, request);
-    const formArgs = this.assignFormArgs(method, body, query);
+    const formArgs = this.assignFormArgs(method, body, query, options);
     body = formArgs.body;
     query = formArgs.query;
+    options = formArgs.options; // Kotlin generator ignores options down the line currently
     let result = this.argFill('', body);
     result = this.argFill(result, query);
     return result;

packages/sdk-codegen/src/python.gen.spec.ts

@@ -81,6 +81,7 @@ import warnings
 
 from . import models as mdls
 from looker_sdk.rtl import api_methods
+from looker_sdk.rtl import model
 from looker_sdk.rtl import transport
 
 class LookerSDK(api_methods.APIMethods):

packages/sdk-codegen/src/python.gen.ts

@@ -105,6 +105,7 @@ import warnings
 
 from . import models as mdls
 from ${this.packagePath}.rtl import api_methods
+from ${this.packagePath}.rtl import model
 from ${this.packagePath}.rtl import transport
 
 class ${this.packageName}(api_methods.APIMethods):
@@ -371,16 +372,22 @@ ${this.hooks.join('\n')}
 
   httpArgs(callerIndent: string, method: IMethod): string {
     const currIndent = this.bumper(callerIndent);
-    let args = '';
-    args = this.argFill(
-      args,
-      `${currIndent}transport_options=transport_options`
-    );
     const body = method.bodyArg ? method.bodyArg : this.nullStr;
     const query = method.queryArgs.length
       ? this.argGroup('', method.queryArgs)
       : this.nullStr;
-    const formArgs = this.assignFormArgs(method, body, query);
+    const formArgs = this.assignFormArgs(
+      method,
+      body,
+      query,
+      'transport_options'
+    );
+
+    let args = '';
+    args = this.argFill(
+      args,
+      `${currIndent}transport_options=${formArgs.options}`
+    );
 
     if (formArgs.body !== this.nullStr) {
       args = this.argFill(args, `${currIndent}body=${formArgs.body}`);
@@ -438,6 +445,19 @@ ${this.hooks.join('\n')}
     return encodings;
   }
 
+  assignFormArgs(
+    method: IMethod,
+    body: string,
+    query: string,
+    options: string
+  ): { body: string; query: string; options: string } {
+    if (method.isFormUrlEncoded) {
+      body = `model.URLSearchParams(${query})`;
+      query = this.nullStr;
+    }
+    return { body, query, options };
+  }
+
   declareMethod(indent: string, method: IMethod) {
     const bump = this.bumper(indent);