Generating URLs from JSON data
You can use JSON data to create a standard URL query. The result is a root URL, followed by a question mark, followed by a list of URL argument assignments from JSON data, separated by ampersands. The syntax is similar to:
http://example.com/page?arg1=val1&arg2=val2Create a URL of this type
using the static Gosu enhancement method makeUrl on the java.net.URL class. Pass a base
URL as the first argument, and the JSON data as the second argument.
The JSON data must be a bindings object like javax.script.SimpleBindings or
anything that implements interface javax.script.Bindings.
A Gosu expando object, such as the Gosu class Expando, satisfies the Bindings requirement.
The following example Gosu code creates
JSON-like data in two ways and generates a URL that uses the JSON data
for query arguments with String
and number values. Numbers are coerced to a String to serialize them into
text.
uses gw.lang.reflect.Expando
uses java.net.URL
var rootUrl = "http://example.com/en"
// ** Using Dynamic type and intialization syntax
var d: dynamic.Dynamic = new() {
:Name = "Andy Applegate",
:Age = 39
}
var url = URL.makeUrl(rootUrl, d)
print("Using dynamic bindings object = " + url)
// ** Using explicit Expando instantiation
var e : dynamic.Dynamic = new Expando()
e.Name = "John Smith"
e.Age = 44
url = URL.makeUrl(rootUrl, e)
print("Using dynamic expando object = " + url)This code prints:
Using dynamic bindings object = http://example.com/en?Name=Andy+Applegate&Age=39
Using dynamic expando object = http://example.com/en?Name=John+Smith&Age=44Note that space characters became + characters. This transformation
is part of the process called URL encoding. Be aware that some special
characters may become multiple characters as part of URL encoding.
The previous example used Bindings values that were String objects or numbers. The
makeUrl method also supports
values of other complex types:
- If the value is a javax.script.Bindings object,
a Gosu dynamic expando object, or a list, Gosu transforms the object
to JSON
Stringdata. - Any other value is coerced
to a
String.
Finally, in all cases, the values are URL encoded before becoming part of the final URL.
The following example creates a new URL
from a Bindings object
with values that include one Bindings
object and one object of list type List<String>:
uses javax.script.Bindings
uses java.net.URL
var rootUrl = "http://example.com/en"
var d: dynamic.Dynamic = new() {
:Who = new() { :FirstName="Andy", :LastName="Applegate" },
:Likes = {"Hiking", "Football"}
}
print("JSON of :Who = " + d.Who.toJson())
print("JSON of :Likes = " + Bindings.listToJson(d.Likes))
var url = URL.makeUrl(rootUrl, d)
print ("URL encoding = " + url)The URL output for this example is harder to read
because of URL encoding of special characters such as braces, comma characters,
and new-line characters. Also, multiple + characters represent space characters
for each line of indented JSON.
This example prints the following, which is shown formatted with added new lines in the URL for clarity:
JSON of :Who = {
"FirstName": "Andy",
"LastName": "Applegate"
}
JSON of :Likes = [
"Hiking",
"Football"
]
URL encoding = http://example.com/en
?Who=%7B%0A++%22FirstName%22%3A+%22Andy%22%2C%0A++%22LastName%22%3A+%22Applegate%22%0A%7D
&Likes=%5B%0A++++%22Hiking%22%2C%0A++++%22Football%22%0A++%5DSee also