api_client.go
func (c *APIClient) prepareRequest(
	ctx context.Context,
	path string, method string,
	postBody interface{},
	headerParams map[string]string,
	queryParams url.Values,
	formParams url.Values,
	fileName string,
	fileBytes []byte) (localVarRequest *http.Request, err error) {

	var body *bytes.Buffer

	// Detect postBody type and post.
	if postBody != nil {
		contentType := headerParams["Content-Type"]
		if contentType == "" {
			contentType = detectContentType(postBody)
			headerParams["Content-Type"] = contentType
		}

		body, err = setBody(postBody, contentType)
		if err != nil {
			return nil, err
		}
	}

	// add form parameters and file if available.
	if len(formParams) > 0 || (len(fileBytes) > 0 && fileName != "") {
		if body != nil {
			return nil, errors.New("Cannot specify postBody and multipart form at the same time.")
		}
		body = &bytes.Buffer{}
		w := multipart.NewWriter(body)

		for k, v := range formParams {
			for _, iv := range v {
				if strings.HasPrefix(k, "@") { // file
					err = addFile(w, k[1:], iv)
					if err != nil {
						return nil, err
					}
				} else { // form value
					w.WriteField(k, iv)
				}
			}
		}
		if len(fileBytes) > 0 && fileName != "" {
			w.Boundary()
			//_, fileNm := filepath.Split(fileName)
			part, err := w.CreateFormFile("file", filepath.Base(fileName))
			if err != nil {
				return nil, err
			}
			_, err = part.Write(fileBytes)
			if err != nil {
				return nil, err
			}
			// Set the Boundary in the Content-Type
			headerParams["Content-Type"] = w.FormDataContentType()
		}

		// Set Content-Length
		headerParams["Content-Length"] = fmt.Sprintf("%d", body.Len())
		w.Close()
	}

	// Setup path and query parameters
	url, err := url.Parse(path)
	if err != nil {
		return nil, err
	}

	// Adding Query Param
	query := url.Query()
	for k, v := range queryParams {
		for _, iv := range v {
			query.Add(k, iv)
		}
	}

	// Encode the parameters.
	url.RawQuery = query.Encode()

	// Generate a new request
	if body != nil {
		localVarRequest, err = http.NewRequest(method, url.String(), body)
	} else {
		localVarRequest, err = http.NewRequest(method, url.String(), nil)
	}
	if err != nil {
		return nil, err
	}

	// add header parameters, if any
	if len(headerParams) > 0 {
		headers := http.Header{}
		for h, v := range headerParams {
			headers.Set(h, v)
		}
		localVarRequest.Header = headers
	}

	// Override request host, if applicable
	if c.cfg.Host != "" {
		localVarRequest.Host = c.cfg.Host
	}

	// Add the user agent to the request.
	localVarRequest.Header.Add("User-Agent", c.cfg.UserAgent)

	if ctx != nil {
		// add context to the request
		localVarRequest = localVarRequest.WithContext(ctx)

		// Walk through any authentication.

		// OAuth2 authentication
		if tok, ok := ctx.Value(ContextOAuth2).(oauth2.TokenSource); ok {
			// We were able to grab an oauth2 token from the context
			var latestToken *oauth2.Token
			if latestToken, err = tok.Token(); err != nil {
				return nil, err
			}

			latestToken.SetAuthHeader(localVarRequest)
		}

		// Basic HTTP Authentication
		if auth, ok := ctx.Value(ContextBasicAuth).(BasicAuth); ok {
			localVarRequest.SetBasicAuth(auth.UserName, auth.Password)
		}

		// AccessToken Authentication
		if auth, ok := ctx.Value(ContextAccessToken).(string); ok {
			localVarRequest.Header.Add("Authorization", "Bearer "+auth)
		}
	}

	for header, value := range c.cfg.DefaultHeader {
		localVarRequest.Header.Add(header, value)
	}

	return localVarRequest, nil
}
func (c *APIClient) prepareRequest(
	ctx context.Context,
	path string, method string,
	postBody interface{},
	headerParams map[string]string,
	queryParams url.Values,
	formParams url.Values,
	fileName string,
	fileBytes []byte) (localVarRequest *http.Request, err error) {

	var body *bytes.Buffer

	// Detect postBody type and post.
	if postBody != nil {
		contentType := headerParams["Content-Type"]
		if contentType == "" {
			contentType = detectContentType(postBody)
			headerParams["Content-Type"] = contentType
		}

		body, err = setBody(postBody, contentType)
		if err != nil {
			return nil, err
		}
	}

	// add form parameters and file if available.
	if len(formParams) > 0 || (len(fileBytes) > 0 && fileName != "") {
		if body != nil {
			return nil, errors.New("Cannot specify postBody and multipart form at the same time.")
		}
		body = &bytes.Buffer{}
		w := multipart.NewWriter(body)

		for k, v := range formParams {
			for _, iv := range v {
				if strings.HasPrefix(k, "@") { // file
					err = addFile(w, k[1:], iv)
					if err != nil {
						return nil, err
					}
				} else { // form value
					w.WriteField(k, iv)
				}
			}
		}
		if len(fileBytes) > 0 && fileName != "" {
			w.Boundary()
			//_, fileNm := filepath.Split(fileName)
			part, err := w.CreateFormFile("file", filepath.Base(fileName))
			if err != nil {
				return nil, err
			}
			_, err = part.Write(fileBytes)
			if err != nil {
				return nil, err
			}
			// Set the Boundary in the Content-Type
			headerParams["Content-Type"] = w.FormDataContentType()
		}

		// Set Content-Length
		headerParams["Content-Length"] = fmt.Sprintf("%d", body.Len())
		w.Close()
	}

	// Setup path and query parameters
	url, err := url.Parse(path)
	if err != nil {
		return nil, err
	}

	// Adding Query Param
	query := url.Query()
	for k, v := range queryParams {
		for _, iv := range v {
			query.Add(k, iv)
		}
	}

	// Encode the parameters.
	url.RawQuery = query.Encode()

	// Generate a new request
	if body != nil {
		localVarRequest, err = http.NewRequest(method, url.String(), body)
	} else {
		localVarRequest, err = http.NewRequest(method, url.String(), nil)
	}
	if err != nil {
		return nil, err
	}

	// add header parameters, if any
	if len(headerParams) > 0 {
		headers := http.Header{}
		for h, v := range headerParams {
			headers.Set(h, v)
		}
		localVarRequest.Header = headers
	}

	// Override request host, if applicable
	if c.cfg.Host != "" {
		localVarRequest.Host = c.cfg.Host
	}

	// Add the user agent to the request.
	localVarRequest.Header.Add("User-Agent", c.cfg.UserAgent)

	if ctx != nil {
		// add context to the request
		localVarRequest = localVarRequest.WithContext(ctx)

		// Walk through any authentication.

		// OAuth2 authentication
		if tok, ok := ctx.Value(ContextOAuth2).(oauth2.TokenSource); ok {
			// We were able to grab an oauth2 token from the context
			var latestToken *oauth2.Token
			if latestToken, err = tok.Token(); err != nil {
				return nil, err
			}

			latestToken.SetAuthHeader(localVarRequest)
		}

		// Basic HTTP Authentication
		if auth, ok := ctx.Value(ContextBasicAuth).(BasicAuth); ok {
			localVarRequest.SetBasicAuth(auth.UserName, auth.Password)
		}

		// AccessToken Authentication
		if auth, ok := ctx.Value(ContextAccessToken).(string); ok {
			localVarRequest.Header.Add("Authorization", "Bearer "+auth)
		}
	}

	for header, value := range c.cfg.DefaultHeader {
		localVarRequest.Header.Add(header, value)
	}

	return localVarRequest, nil
}
// prepareRequest build the request