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soup.go
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soup.go
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/* soup package implements a simple web scraper for Go,
keeping it as similar as possible to BeautifulSoup
*/
package soup
import (
"bytes"
"crypto/tls"
"encoding/json"
"fmt"
"io"
"io/ioutil"
"net/http"
"net/http/httputil"
"net/url"
netURL "net/url"
"regexp"
"strings"
"golang.org/x/net/html"
"golang.org/x/net/html/charset"
)
// ErrorType defines types of errors that are possible from soup
type ErrorType int
const (
// ErrUnableToParse will be returned when the HTML could not be parsed
ErrUnableToParse ErrorType = iota
// ErrElementNotFound will be returned when element was not found
ErrElementNotFound
// ErrNoNextSibling will be returned when no next sibling can be found
ErrNoNextSibling
// ErrNoPreviousSibling will be returned when no previous sibling can be found
ErrNoPreviousSibling
// ErrNoNextElementSibling will be returned when no next element sibling can be found
ErrNoNextElementSibling
// ErrNoPreviousElementSibling will be returned when no previous element sibling can be found
ErrNoPreviousElementSibling
// ErrCreatingGetRequest will be returned when the get request couldn't be created
ErrCreatingGetRequest
// ErrInGetRequest will be returned when there was an error during the get request
ErrInGetRequest
// ErrCreatingPostRequest will be returned when the post request couldn't be created
ErrCreatingPostRequest
// ErrMarshallingPostRequest will be returned when the body of a post request couldn't be serialized
ErrMarshallingPostRequest
// ErrReadingResponse will be returned if there was an error reading the response to our get request
ErrReadingResponse
)
// Error allows easier introspection on the type of error returned.
// If you know you have a Error, you can compare the Type to one of the exported types
// from this package to see what kind of error it is, then further inspect the Error() method
// to see if it has more specific details for you, like in the case of a ErrElementNotFound
// type of error.
type Error struct {
Type ErrorType
msg string
}
func (se Error) Error() string {
return se.msg
}
func newError(t ErrorType, msg string) Error {
return Error{Type: t, msg: msg}
}
// Root is a structure containing a pointer to an html node, the node value, and an error variable to return an error if one occurred
type Root struct {
Pointer *html.Node
NodeValue string
Error error
}
// Init a new HTTP client for use when the client doesn't want to use their own.
var (
defaultClient = &http.Client{}
debug = false
// Headers contains all HTTP headers to send
Headers = make(map[string]string)
// Cookies contains all HTTP cookies to send
Cookies = make(map[string]string)
)
// SetDebug sets the debug status
// Setting this to true causes the panics to be thrown and logged onto the console.
// Setting this to false causes the errors to be saved in the Error field in the returned struct.
func SetDebug(d bool) {
debug = d
}
// Header sets a new HTTP header
func Header(n string, v string) {
Headers[n] = v
}
// Cookie sets a cookie for http requests
func Cookie(n string, v string) {
Cookies[n] = v
}
// GetWithClient returns the HTML returned by the url using a provided HTTP client
func GetWithClient(url string, client *http.Client) (string, error) {
http.DefaultTransport.(*http.Transport).TLSClientConfig = &tls.Config{InsecureSkipVerify: true}
req, err := http.NewRequest("GET", url, nil)
if err != nil {
if debug {
panic("Couldn't create GET request to " + url)
}
return "", newError(ErrCreatingGetRequest, "error creating get request to "+url)
}
setHeadersAndCookies(req)
// Perform request
resp, err := client.Do(req)
if err != nil {
if debug {
panic("Couldn't perform GET request to " + url)
}
return "", newError(ErrInGetRequest, "couldn't perform GET request to "+url)
}
defer resp.Body.Close()
utf8Body, err := charset.NewReader(resp.Body, resp.Header.Get("Content-Type"))
if err != nil {
return "", err
}
bytes, err := ioutil.ReadAll(utf8Body)
if err != nil {
if debug {
panic("Unable to read the response body")
}
return "", newError(ErrReadingResponse, "unable to read the response body")
}
return string(bytes), nil
}
// setHeadersAndCookies helps build a request
func setHeadersAndCookies(req *http.Request) {
// Set headers
for hName, hValue := range Headers {
req.Header.Set(hName, hValue)
}
// Set cookies
for cName, cValue := range Cookies {
req.AddCookie(&http.Cookie{
Name: cName,
Value: cValue,
})
}
}
// getBodyReader serializes the body for a network request. See the test file for examples
func getBodyReader(rawBody interface{}) (io.Reader, error) {
var bodyReader io.Reader
if rawBody != nil {
switch body := rawBody.(type) {
case map[string]string:
jsonBody, err := json.Marshal(body)
if err != nil {
if debug {
panic("Unable to read the response body")
}
return nil, newError(ErrMarshallingPostRequest, "couldn't serialize map of strings to JSON.")
}
bodyReader = bytes.NewBuffer(jsonBody)
case netURL.Values:
bodyReader = strings.NewReader(body.Encode())
case []byte: //expects JSON format
bodyReader = bytes.NewBuffer(body)
case string: //expects JSON format
bodyReader = strings.NewReader(body)
default:
return nil, newError(ErrMarshallingPostRequest, fmt.Sprintf("Cannot handle body type %T", rawBody))
}
}
return bodyReader, nil
}
// PostWithClient returns the HTML returned by the url using a provided HTTP client
// The type of the body must conform to one of the types listed in func getBodyReader()
func PostWithClient(url string, bodyType string, body interface{}, client *http.Client) (string, error) {
bodyReader, err := getBodyReader(body)
if err != nil {
return "todo:", err
}
req, err := http.NewRequest("POST", url, bodyReader)
Header("Content-Type", bodyType)
setHeadersAndCookies(req)
if debug {
// Save a copy of this request for debugging.
requestDump, err := httputil.DumpRequest(req, true)
if err != nil {
fmt.Println(err)
}
fmt.Println(string(requestDump))
}
// Perform request
resp, err := client.Do(req)
if err != nil {
if debug {
panic("Couldn't perform POST request to " + url)
}
return "", newError(ErrCreatingPostRequest, "couldn't perform POST request to"+url)
}
defer resp.Body.Close()
bytes, err := ioutil.ReadAll(resp.Body)
if err != nil {
if debug {
panic("Unable to read the response body")
}
return "", newError(ErrReadingResponse, "unable to read the response body")
}
return string(bytes), nil
}
// Post returns the HTML returned by the url as a string using the default HTTP client
func Post(url string, bodyType string, body interface{}) (string, error) {
return PostWithClient(url, bodyType, body, defaultClient)
}
// PostForm is a convenience method for POST requests that
func PostForm(url string, data url.Values) (string, error) {
return PostWithClient(url, "application/x-www-form-urlencoded", data, defaultClient)
}
// Get returns the HTML returned by the url as a string using the default HTTP client
func Get(url string) (string, error) {
return GetWithClient(url, defaultClient)
}
// HTMLParse parses the HTML returning a start pointer to the DOM
func HTMLParse(s string) Root {
r, err := html.Parse(strings.NewReader(s))
if err != nil {
if debug {
panic("Unable to parse the HTML")
}
return Root{Error: newError(ErrUnableToParse, "unable to parse the HTML")}
}
for r.Type != html.ElementNode {
switch r.Type {
case html.DocumentNode:
r = r.FirstChild
case html.DoctypeNode:
r = r.NextSibling
case html.CommentNode:
r = r.NextSibling
}
}
return Root{Pointer: r, NodeValue: r.Data}
}
// Find finds the first occurrence of the given tag name,
// with or without attribute key and value specified,
// and returns a struct with a pointer to it
func (r Root) Find(args ...string) Root {
temp, ok := findOnce(r.Pointer, args, false, false)
if ok == false {
if debug {
panic("Element `" + args[0] + "` with attributes `" + strings.Join(args[1:], " ") + "` not found")
}
return Root{Error: newError(ErrElementNotFound, fmt.Sprintf("element `%s` with attributes `%s` not found", args[0], strings.Join(args[1:], " ")))}
}
return Root{Pointer: temp, NodeValue: temp.Data}
}
// FindAll finds all occurrences of the given tag name,
// with or without key and value specified,
// and returns an array of structs, each having
// the respective pointers
func (r Root) FindAll(args ...string) []Root {
temp := findAllofem(r.Pointer, args, false)
if len(temp) == 0 {
if debug {
panic("Element `" + args[0] + "` with attributes `" + strings.Join(args[1:], " ") + "` not found")
}
return []Root{}
}
pointers := make([]Root, 0, len(temp))
for i := 0; i < len(temp); i++ {
pointers = append(pointers, Root{Pointer: temp[i], NodeValue: temp[i].Data})
}
return pointers
}
// FindStrict finds the first occurrence of the given tag name
// only if all the values of the provided attribute are an exact match
func (r Root) FindStrict(args ...string) Root {
temp, ok := findOnce(r.Pointer, args, false, true)
if ok == false {
if debug {
panic("Element `" + args[0] + "` with attributes `" + strings.Join(args[1:], " ") + "` not found")
}
return Root{nil, "", newError(ErrElementNotFound, fmt.Sprintf("element `%s` with attributes `%s` not found", args[0], strings.Join(args[1:], " ")))}
}
return Root{Pointer: temp, NodeValue: temp.Data}
}
// FindAllStrict finds all occurrences of the given tag name
// only if all the values of the provided attribute are an exact match
func (r Root) FindAllStrict(args ...string) []Root {
temp := findAllofem(r.Pointer, args, true)
if len(temp) == 0 {
if debug {
panic("Element `" + args[0] + "` with attributes `" + strings.Join(args[1:], " ") + "` not found")
}
return []Root{}
}
pointers := make([]Root, 0, len(temp))
for i := 0; i < len(temp); i++ {
pointers = append(pointers, Root{Pointer: temp[i], NodeValue: temp[i].Data})
}
return pointers
}
// FindNextSibling finds the next sibling of the pointer in the DOM
// returning a struct with a pointer to it
func (r Root) FindNextSibling() Root {
nextSibling := r.Pointer.NextSibling
if nextSibling == nil {
if debug {
panic("No next sibling found")
}
return Root{Error: newError(ErrNoNextSibling, "no next sibling found")}
}
return Root{Pointer: nextSibling, NodeValue: nextSibling.Data}
}
// FindPrevSibling finds the previous sibling of the pointer in the DOM
// returning a struct with a pointer to it
func (r Root) FindPrevSibling() Root {
prevSibling := r.Pointer.PrevSibling
if prevSibling == nil {
if debug {
panic("No previous sibling found")
}
return Root{Error: newError(ErrNoPreviousSibling, "no previous sibling found")}
}
return Root{Pointer: prevSibling, NodeValue: prevSibling.Data}
}
// FindNextElementSibling finds the next element sibling of the pointer in the DOM
// returning a struct with a pointer to it
func (r Root) FindNextElementSibling() Root {
nextSibling := r.Pointer.NextSibling
if nextSibling == nil {
if debug {
panic("No next element sibling found")
}
return Root{Error: newError(ErrNoNextElementSibling, "no next element sibling found")}
}
if nextSibling.Type == html.ElementNode {
return Root{Pointer: nextSibling, NodeValue: nextSibling.Data}
}
p := Root{Pointer: nextSibling, NodeValue: nextSibling.Data}
return p.FindNextElementSibling()
}
// FindPrevElementSibling finds the previous element sibling of the pointer in the DOM
// returning a struct with a pointer to it
func (r Root) FindPrevElementSibling() Root {
prevSibling := r.Pointer.PrevSibling
if prevSibling == nil {
if debug {
panic("No previous element sibling found")
}
return Root{Error: newError(ErrNoPreviousElementSibling, "no previous element sibling found")}
}
if prevSibling.Type == html.ElementNode {
return Root{Pointer: prevSibling, NodeValue: prevSibling.Data}
}
p := Root{Pointer: prevSibling, NodeValue: prevSibling.Data}
return p.FindPrevElementSibling()
}
// Children retuns all direct children of this DOME element.
func (r Root) Children() []Root {
child := r.Pointer.FirstChild
var children []Root
for child != nil {
children = append(children, Root{Pointer: child, NodeValue: child.Data})
child = child.NextSibling
}
return children
}
// Attrs returns a map containing all attributes
func (r Root) Attrs() map[string]string {
if r.Pointer.Type != html.ElementNode {
if debug {
panic("Not an ElementNode")
}
return nil
}
if len(r.Pointer.Attr) == 0 {
return nil
}
return getKeyValue(r.Pointer.Attr)
}
// Text returns the string inside a non-nested element
func (r Root) Text() string {
k := r.Pointer.FirstChild
checkNode:
if k != nil && k.Type != html.TextNode {
k = k.NextSibling
if k == nil {
if debug {
panic("No text node found")
}
return ""
}
goto checkNode
}
if k != nil {
r, _ := regexp.Compile(`^\s+$`)
if ok := r.MatchString(k.Data); ok {
k = k.NextSibling
if k == nil {
if debug {
panic("No text node found")
}
return ""
}
goto checkNode
}
return k.Data
}
return ""
}
// HTML returns the HTML code for the specific element
func (r Root) HTML() string {
var buf bytes.Buffer
if err := html.Render(&buf, r.Pointer); err != nil {
return ""
}
return buf.String()
}
// FullText returns the string inside even a nested element
func (r Root) FullText() string {
var buf bytes.Buffer
var f func(*html.Node)
f = func(n *html.Node) {
if n == nil {
return
}
if n.Type == html.TextNode {
buf.WriteString(n.Data)
}
if n.Type == html.ElementNode {
f(n.FirstChild)
}
if n.NextSibling != nil {
f(n.NextSibling)
}
}
f(r.Pointer.FirstChild)
return buf.String()
}
func matchElementName(n *html.Node, name string) bool {
return name == "" || name == n.Data
}
// Using depth first search to find the first occurrence and return
func findOnce(n *html.Node, args []string, uni bool, strict bool) (*html.Node, bool) {
if uni == true {
if n.Type == html.ElementNode && matchElementName(n, args[0]) {
if len(args) > 1 && len(args) < 4 {
for i := 0; i < len(n.Attr); i++ {
attr := n.Attr[i]
searchAttrName := args[1]
searchAttrVal := args[2]
if (strict && attributeAndValueEquals(attr, searchAttrName, searchAttrVal)) ||
(!strict && attributeContainsValue(attr, searchAttrName, searchAttrVal)) {
return n, true
}
}
} else if len(args) == 1 {
return n, true
}
}
}
uni = true
for c := n.FirstChild; c != nil; c = c.NextSibling {
p, q := findOnce(c, args, true, strict)
if q != false {
return p, q
}
}
return nil, false
}
// Using depth first search to find all occurrences and return
func findAllofem(n *html.Node, args []string, strict bool) []*html.Node {
var nodeLinks = make([]*html.Node, 0, 10)
var f func(*html.Node, []string, bool)
f = func(n *html.Node, args []string, uni bool) {
if uni == true {
if n.Type == html.ElementNode && matchElementName(n, args[0]) {
if len(args) > 1 && len(args) < 4 {
for i := 0; i < len(n.Attr); i++ {
attr := n.Attr[i]
searchAttrName := args[1]
searchAttrVal := args[2]
if (strict && attributeAndValueEquals(attr, searchAttrName, searchAttrVal)) ||
(!strict && attributeContainsValue(attr, searchAttrName, searchAttrVal)) {
nodeLinks = append(nodeLinks, n)
}
}
} else if len(args) == 1 {
nodeLinks = append(nodeLinks, n)
}
}
}
uni = true
for c := n.FirstChild; c != nil; c = c.NextSibling {
f(c, args, true)
}
}
f(n, args, false)
return nodeLinks
}
// attributeAndValueEquals reports when the html.Attribute attr has the same attribute name and value as from
// provided arguments
func attributeAndValueEquals(attr html.Attribute, attribute, value string) bool {
return attr.Key == attribute && attr.Val == value
}
// attributeContainsValue reports when the html.Attribute attr has the same attribute name as from provided
// attribute argument and compares if it has the same value in its values parameter
func attributeContainsValue(attr html.Attribute, attribute, value string) bool {
if attr.Key == attribute {
for _, attrVal := range strings.Fields(attr.Val) {
if attrVal == value {
return true
}
}
}
return false
}
// Returns a key pair value (like a dictionary) for each attribute
func getKeyValue(attributes []html.Attribute) map[string]string {
var keyvalues = make(map[string]string)
for i := 0; i < len(attributes); i++ {
_, exists := keyvalues[attributes[i].Key]
if exists == false {
keyvalues[attributes[i].Key] = attributes[i].Val
}
}
return keyvalues
}