issue#2543: added api_client to set content-type and accept for http request

modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/GoClientCodegen.java

@@ -134,6 +134,7 @@ public class GoClientCodegen extends DefaultCodegen implements CodegenConfig {
         supportingFiles.add(new SupportingFile("git_push.sh.mustache", "", "git_push.sh"));
         supportingFiles.add(new SupportingFile("gitignore.mustache", "", ".gitignore"));
         supportingFiles.add(new SupportingFile("configuration.mustache", packageName, "configuration.go"));
+        supportingFiles.add(new SupportingFile("api_client.mustache", packageName, "api_client.go"));
     }
 
     @Override

modules/swagger-codegen/src/main/resources/go/api.mustache

@@ -86,11 +86,29 @@ func (a {{classname}}) {{nickname}} ({{#allParams}}{{paramName}} {{{dataType}}}{
 }
     _sling = _sling.QueryStruct(&QueryParams{ {{#queryParams}}{{vendorExtensions.x-exportParamName}}: {{paramName}}{{#hasMore}},{{/hasMore}}{{/queryParams}} })
 {{/hasQueryParams}}
-    // accept header
-    accepts := []string { {{#produces}}"{{mediaType}}"{{#hasMore}}, {{/hasMore}}{{/produces}} }
-    for key := range accepts {
-        _sling = _sling.Set("Accept", accepts[key])
-        break // only use the first Accept
+
+    // to determine the Content-Type header
+    localVarHttpContentTypes := []string {
+        {{#consumes}}
+        "{{mediaType}}", 
+        {{/consumes}}
+    }
+    //set Content-Type header
+    localVarHttpContentType := a.Configuration.ApiClient.SelectHeaderContentType(localVarHttpContentTypes)
+    if localVarHttpContentType != "" {    
+      _sling = _sling.Set("Content-Type", localVarHttpContentType)
+    }
+
+    // to determine the Accept header
+    localVarHttpHeaderAccepts := []string {
+        {{#produces}}
+        "{{mediaType}}", 
+        {{/produces}}
+    }
+    //set Accept header
+    localVarHttpHeaderAccept := a.Configuration.ApiClient.SelectHeaderAccept(localVarHttpHeaderAccepts)
+    if localVarHttpHeaderAccept != "" {  
+        _sling = _sling.Set("Accept", localVarHttpHeaderAccept)
     }
 {{#hasHeaderParams}}{{#headerParams}}    // header params "{{baseName}}"
     _sling = _sling.Set("{{baseName}}", {{paramName}})

modules/swagger-codegen/src/main/resources/go/api_client.mustache

@@ -0,0 +1,41 @@
+package {{packageName}}
+
+import (
+    "strings"
+)
+
+type ApiClient struct {
+
+}
+
+func (c *ApiClient) SelectHeaderContentType(contentTypes []string) string {
+    if (len(contentTypes) == 0){
+        return ""
+    }
+    if contains(contentTypes,"application/json") {
+        return "application/json"
+    }
+
+    return contentTypes[0] // use the first content type specified in 'consumes'
+}
+
+func (c *ApiClient) SelectHeaderAccept(accepts []string) string {
+    if (len(accepts) == 0){        
+        return ""
+    }
+
+    if contains(accepts,"application/json"){        
+        return "application/json"
+    }
+
+    return strings.Join(accepts,",")
+}
+
+func contains(source []string, containvalue string) bool {
+    for _, a := range source {
+        if strings.ToLower(a) == strings.ToLower(containvalue) {
+            return true
+        }
+    }
+    return false
+}

modules/swagger-codegen/src/main/resources/go/configuration.mustache

@@ -19,6 +19,7 @@ type Configuration struct {
     AccessToken string `json:"accessToken,omitempty"`
     DefaultHeader map[string]string `json:"defaultHeader,omitempty"`
     UserAgent string `json:"userAgent,omitempty"`
+    ApiClient ApiClient `json:"apiClient,omitempty"`
 }
 
 func NewConfiguration() *Configuration {