implement 'urlQueryEscape' and 'urlQueryUnescape' template functions …

…in filter builder (#1194)

This commit adds the 'urlQueryEscape' and 'urlQueryUnescape' functions to the template's extra functions ('extraFuncs'). These functions provide URL encoding and decoding capabilities.

docs/07.Reference/7.02.Filters.md

@@ -2071,6 +2071,10 @@ package, and extra functions defined by Easegress:
  also an object, its type must also be `map[string]interface{}`.
 * **jsonEscape**: escape a string so that it can be used as the key or value
  in JSON text.
+* **urlQueryEscape**: escapes the string so that it can be safely placed inside
+ a URL query, equivalent to the `urlquery` template function.
+* **urlQueryUnescape**: performs the inverse transformation of `urlQueryEscape`,
+ decoding a URL-encoded string back to its origin form.
 
 Easegress injects existing requests/responses of the current context into
 the template engine at runtime, so we can use `.requests.<namespace>.<field>`

pkg/filters/builder/extrafuncs.go

@@ -21,6 +21,7 @@ import (
  "encoding/json"
  "fmt"
  "net/http"
+ "net/url"
  "strconv"
  "strings"
  "text/template"
@@ -154,4 +155,16 @@ var extraFuncs = template.FuncMap{
  username, _, _ := req.(BasicAuth).BasicAuth()
  return username
  },
+
+ "urlQueryUnescape": func(s string) string {
+ unescapedStr, err := url.QueryUnescape(s)
+ if err != nil {
+ panic(err)
+ }
+ return unescapedStr
+ },
+
+ "urlQueryEscape": func(s string) string {
+ return url.QueryEscape(s)
+ },
 }

pkg/filters/builder/extrafuncs_test.go

@@ -59,6 +59,11 @@ func TestExtraFuncs(t *testing.T) {
 
  assert.Equal(`abcd\"ABCD`, extraFuncs["jsonEscape"].(func(s string) string)(`abcd"ABCD`))
 
+ assert.Equal("https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FUTF-8%23Description",
+ extraFuncs["urlQueryEscape"].(func(s string) string)("https://en.wikipedia.org/wiki/UTF-8#Description"))
+ assert.Equal("https://en.wikipedia.org/wiki/UTF-8#Description",
+ extraFuncs["urlQueryUnescape"].(func(s string) string)("https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FUTF-8%23Description"))
+
  assert.Panics(func() { extraFuncs["panic"].(func(v interface{}))("") })
 }