mirror of
https://github.com/rocky-linux/peridot.git
synced 2024-11-16 18:51:23 +00:00
169 lines
4.7 KiB
Markdown
169 lines
4.7 KiB
Markdown
|
htmlquery
|
||
|
|
====
|
||
|
|
[](https://travis-ci.org/antchfx/htmlquery)
|
||
|
|
[](https://coveralls.io/github/antchfx/htmlquery?branch=master)
|
||
|
|
[](https://godoc.org/github.com/antchfx/htmlquery)
|
||
|
|
[](https://goreportcard.com/report/github.com/antchfx/htmlquery)
|
||
|
|
|
||
|
|
Overview
|
||
|
|
====
|
||
|
|
|
||
|
|
`htmlquery` is an XPath query package for HTML, lets you extract data or evaluate from HTML documents by an XPath expression.
|
||
|
|
|
||
|
|
`htmlquery` built-in the query object caching feature based on [LRU](https://godoc.org/github.com/golang/groupcache/lru), this feature will caching the recently used XPATH query string. Enable query caching can avoid re-compile XPath expression each query.
|
||
|
|
|
||
|
|
Installation
|
||
|
|
====
|
||
|
|
|
||
|
|
```
|
||
|
|
go get github.com/antchfx/htmlquery
|
||
|
|
```
|
||
|
|
|
||
|
|
Getting Started
|
||
|
|
====
|
||
|
|
|
||
|
|
#### Query, returns matched elements or error.
|
||
|
|
|
||
|
|
```go
|
||
|
|
nodes, err := htmlquery.QueryAll(doc, "//a")
|
||
|
|
if err != nil {
|
||
|
|
panic(`not a valid XPath expression.`)
|
||
|
|
}
|
||
|
|
```
|
||
|
|
|
||
|
|
#### Load HTML document from URL.
|
||
|
|
|
||
|
|
```go
|
||
|
|
doc, err := htmlquery.LoadURL("http://example.com/")
|
||
|
|
```
|
||
|
|
|
||
|
|
#### Load HTML from document.
|
||
|
|
|
||
|
|
```go
|
||
|
|
filePath := "/home/user/sample.html"
|
||
|
|
doc, err := htmlquery.LoadDoc(filePath)
|
||
|
|
```
|
||
|
|
|
||
|
|
#### Load HTML document from string.
|
||
|
|
|
||
|
|
```go
|
||
|
|
s := `<html>....</html>`
|
||
|
|
doc, err := htmlquery.Parse(strings.NewReader(s))
|
||
|
|
```
|
||
|
|
|
||
|
|
#### Find all A elements.
|
||
|
|
|
||
|
|
```go
|
||
|
|
list := htmlquery.Find(doc, "//a")
|
||
|
|
```
|
||
|
|
|
||
|
|
#### Find all A elements that have `href` attribute.
|
||
|
|
|
||
|
|
```go
|
||
|
|
list := range htmlquery.Find(doc, "//a[@href]")
|
||
|
|
```
|
||
|
|
|
||
|
|
#### Find all A elements with `href` attribute and only return `href` value.
|
||
|
|
|
||
|
|
```go
|
||
|
|
list := range htmlquery.Find(doc, "//a/@href")
|
||
|
|
for n := range list{
|
||
|
|
fmt.Println(htmlquery.InnerText(n)) // output @href value without A element.
|
||
|
|
}
|
||
|
|
```
|
||
|
|
|
||
|
|
### Find the third A element.
|
||
|
|
|
||
|
|
```go
|
||
|
|
a := htmlquery.FindOne(doc, "//a[3]")
|
||
|
|
```
|
||
|
|
|
||
|
|
#### Evaluate the number of all IMG element.
|
||
|
|
|
||
|
|
```go
|
||
|
|
expr, _ := xpath.Compile("count(//img)")
|
||
|
|
v := expr.Evaluate(htmlquery.CreateXPathNavigator(doc)).(float64)
|
||
|
|
fmt.Printf("total count is %f", v)
|
||
|
|
```
|
||
|
|
|
||
|
|
|
||
|
|
FAQ
|
||
|
|
====
|
||
|
|
|
||
|
|
#### `Find()` vs `QueryAll()`, which is better?
|
||
|
|
|
||
|
|
`Find` and `QueryAll` both do the same things, searches all of matched html nodes.
|
||
|
|
The `Find` will panics if you give an error XPath query, but `QueryAll` will return an error for you.
|
||
|
|
|
||
|
|
#### Can I save my query expression object for the next query?
|
||
|
|
|
||
|
|
Yes, you can. We offer the `QuerySelector` and `QuerySelectorAll` methods, It will accept your query expression object.
|
||
|
|
|
||
|
|
Cache a query expression object(or reused) will avoid re-compile XPath query expression, improve your query performance.
|
||
|
|
|
||
|
|
#### XPath query object cache performance
|
||
|
|
|
||
|
|
```
|
||
|
|
goos: windows
|
||
|
|
goarch: amd64
|
||
|
|
pkg: github.com/antchfx/htmlquery
|
||
|
|
BenchmarkSelectorCache-4 20000000 55.2 ns/op
|
||
|
|
BenchmarkDisableSelectorCache-4 500000 3162 ns/op
|
||
|
|
```
|
||
|
|
|
||
|
|
#### How to disable caching?
|
||
|
|
|
||
|
|
```
|
||
|
|
htmlquery.DisableSelectorCache = true
|
||
|
|
```
|
||
|
|
|
||
|
|
Changelogs
|
||
|
|
===
|
||
|
|
|
||
|
|
2019-11-19
|
||
|
|
- Add built-in query object cache feature, avoid re-compilation for the same query string. [#16](https://github.com/antchfx/htmlquery/issues/16)
|
||
|
|
- Added LoadDoc [18](https://github.com/antchfx/htmlquery/pull/18)
|
||
|
|
|
||
|
|
2019-10-05
|
||
|
|
- Add new methods that compatible with invalid XPath expression error: `QueryAll` and `Query`.
|
||
|
|
- Add `QuerySelector` and `QuerySelectorAll` methods, supported reused your query object.
|
||
|
|
|
||
|
|
2019-02-04
|
||
|
|
- [#7](https://github.com/antchfx/htmlquery/issues/7) Removed deprecated `FindEach()` and `FindEachWithBreak()` methods.
|
||
|
|
|
||
|
|
2018-12-28
|
||
|
|
- Avoid adding duplicate elements to list for `Find()` method. [#6](https://github.com/antchfx/htmlquery/issues/6)
|
||
|
|
|
||
|
|
Tutorial
|
||
|
|
===
|
||
|
|
|
||
|
|
```go
|
||
|
|
func main() {
|
||
|
|
doc, err := htmlquery.LoadURL("https://www.bing.com/search?q=golang")
|
||
|
|
if err != nil {
|
||
|
|
panic(err)
|
||
|
|
}
|
||
|
|
// Find all news item.
|
||
|
|
list, err := htmlquery.QueryAll(doc, "//ol/li")
|
||
|
|
if err != nil {
|
||
|
|
panic(err)
|
||
|
|
}
|
||
|
|
for i, n := range list {
|
||
|
|
a := htmlquery.FindOne(n, "//a")
|
||
|
|
fmt.Printf("%d %s(%s)\n", i, htmlquery.InnerText(a), htmlquery.SelectAttr(a, "href"))
|
||
|
|
}
|
||
|
|
}
|
||
|
|
```
|
||
|
|
|
||
|
|
List of supported XPath query packages
|
||
|
|
===
|
||
|
|
| Name | Description |
|
||
|
|
| ------------------------------------------------- | ----------------------------------------- |
|
||
|
|
| [htmlquery](https://github.com/antchfx/htmlquery) | XPath query package for the HTML document |
|
||
|
|
| [xmlquery](https://github.com/antchfx/xmlquery) | XPath query package for the XML document |
|
||
|
|
| [jsonquery](https://github.com/antchfx/jsonquery) | XPath query package for the JSON document |
|
||
|
|
|
||
|
|
Questions
|
||
|
|
===
|
||
|
|
Please let me know if you have any questions.
|