restyvsrvest
Resty is an HTTP and REST client library for Go. It is designed to be simple and easy to use, while still providing a lot of powerful features. One of the main benefits of using Resty is that it allows you to make HTTP requests with minimal boilerplate code, while still providing a lot of flexibility and control over the requests.
One of the key features of Resty is its use of chaining. This allows you to chain together multiple methods to build up a request, making the code more readable and easy to understand. For example, you can chain together the R().SetHeader("Accept", "application/json") method to set the Accept header and R().SetQueryParam("param1", "value1") to add a query parameter to the request.
Resty also provides a lot of convenience functions for making common types of requests, such as Get, Post, Put, and Delete. This can be useful if you need to make a simple request quickly and don't want to spend a lot of time configuring the request. Additionally, Resty also provides a way to set a timeout for the request, in case the server takes too long to respond.
Resty also supports HTTP/2 and advanced features like multipart file upload, request and response middlewares, request hooks, and many others.
Overall, Resty is a good choice if you're looking for a simple and easy-to-use HTTP client library for Go. It's a good fit for projects that don't require a lot of customization and need a quick way to make HTTP requests.
rvest is a popular R library for web scraping and parsing HTML and XML documents. It is built on top of the xml2 and httr libraries and provides a simple and consistent API for interacting with web pages.
One of the main advantages of using rvest is its simplicity and ease of use. It provides a number of functions that make it easy to extract information from web pages, even for those who are not familiar with web scraping. The html_nodes and html_node functions allow you to select elements from an HTML document using CSS selectors, similar to how you would select elements in JavaScript.
rvest also provides functions for interacting with forms, including html_form, set_values, and submit_form functions. These functions make it easy to navigate through forms and submit data to the server, which can be useful when scraping sites that require authentication or when interacting with dynamic web pages.
rvest also provides functions for parsing XML documents. It includes xml_nodes and xml_node functions, which also use CSS selectors to select elements from an XML document, as well as xml_attrs and xml_attr functions to extract attributes from elements.
Another advantage of rvest is that it provides a way to handle cookies, so you can keep the session alive while scraping a website, and also you can handle redirections with handle_redirects
Example Use
package main
// establish session client
client := resty.New()
// set proxy for the session
client.SetProxy("http://proxyserver:8888")
// set retries
client.
// Set retry count to non zero to enable retries
SetRetryCount(3).
// You can override initial retry wait time.
// Default is 100 milliseconds.
SetRetryWaitTime(5 * time.Second).
// MaxWaitTime can be overridden as well.
// Default is 2 seconds.
SetRetryMaxWaitTime(20 * time.Second).
// SetRetryAfter sets callback to calculate wait time between retries.
// Default (nil) implies exponential backoff with jitter
SetRetryAfter(func(client *resty.Client, resp *resty.Response) (time.Duration, error) {
return 0, errors.New("quota exceeded")
})
// Make GET request
resp, err := client.R().
// we can set query
SetQueryParams(map[string]string{
"query": "foo",
}).
// and headers
SetHeader("Accept", "application/json").
Get("https://httpbin.org/get")
// Make Post request
resp, err := client.R().
// JSON data
SetHeader("Content-Type", "application/json").
SetBody(`{"username":"testuser", "password":"testpass"}`).
// or Form Data
SetFormData(map[string]string{
"username": "jeeva",
"password": "mypass",
}).
Post("https://httpbin.org/post")
// resty also support request and response middlewares
// which allow easy modification of outgoing requests and incoming responses
client.OnBeforeRequest(func(c *resty.Client, req *resty.Request) error {
// Now you have access to Client and current Request object
// manipulate it as per your need
return nil // if its success otherwise return error
})
// Registering Response Middleware
client.OnAfterResponse(func(c *resty.Client, resp *resty.Response) error {
// Now you have access to Client and current Response object
// manipulate it as per your need
return nil // if its success otherwise return error
})
library("rvest")
# Rvest can use basic HTTP client to download remote HTML:
tree <- read_html("http://webscraping.fyi/lib/r/rvest")
# or read from string:
tree <- read_html('
<div class="products">
<a href="/product/1">Cat Food</a>
<a href="/product/2">Dog Food</a>
</div>
')
# to parse HTML trees with rvest we use r pipes (the %>% symbol) and html_element function:
# we can use css selectors:
print(tree %>% html_element(".products>a") %>% html_text())
# "[1] "\nCat Food\nDog Food\n""
# or XPath:
print(tree %>% html_element(xpath="//div[@class='products']/a") %>% html_text())
# "[1] "\nCat Food\nDog Food\n""
# Additionally rvest offers many quality of life functions:
# html_text2 - removes trailing and leading spaces and joins values
print(tree %>% html_element("div") %>% html_text2())
# "[1] "Cat Food Dog Food""
# html_attr - selects element's attribute:
print(tree %>% html_element("div") %>% html_attr('class'))
# "products"