rubycdp
Simple 'browser.evaluate' throws a 'NoMethodError'
Steps to reproduce:
require "ferrum"
browser = Ferrum::Browser.new
browser.go_to("http://grmdaily.com/")
browser.evaluate("pbjs.getConfig()") #throws error stack below
Error Stack:
2022-08-22T15:47:44.660Z pid=86509 tid=3xh WARN: NoMethodError: undefined method `[]' for nil:NilClass
2022-08-22T15:47:44.660Z pid=86509 tid=3xh WARN: /usr/share/rvm/gems/ruby-2.7.2/gems/ferrum-0.11/lib/ferrum/frame/runtime.rb:193:in `block in handle_response'
/usr/share/rvm/gems/ruby-2.7.2/gems/ferrum-0.11/lib/ferrum/frame/runtime.rb:220:in `block in reduce_props'
/usr/share/rvm/gems/ruby-2.7.2/gems/ferrum-0.11/lib/ferrum/frame/runtime.rb:218:in `each'
/usr/share/rvm/gems/ruby-2.7.2/gems/ferrum-0.11/lib/ferrum/frame/runtime.rb:218:in `reduce'
/usr/share/rvm/gems/ruby-2.7.2/gems/ferrum-0.11/lib/ferrum/frame/runtime.rb:218:in `reduce_props'
/usr/share/rvm/gems/ruby-2.7.2/gems/ferrum-0.11/lib/ferrum/frame/runtime.rb:192:in `handle_response'
/usr/share/rvm/gems/ruby-2.7.2/gems/ferrum-0.11/lib/ferrum/frame/runtime.rb:144:in `block in call'
/usr/share/rvm/gems/ruby-2.7.2/gems/ferrum-0.11/lib/ferrum.rb:145:in `with_attempts'
/usr/share/rvm/gems/ruby-2.7.2/gems/ferrum-0.11/lib/ferrum/frame/runtime.rb:124:in `call'
/usr/share/rvm/gems/ruby-2.7.2/gems/ferrum-0.11/lib/ferrum/frame/runtime.rb:50:in `evaluate'
/usr/share/rvm/rubies/ruby-2.7.2/lib/ruby/2.7.0/forwardable.rb:235:in `evaluate'
/usr/share/rvm/rubies/ruby-2.7.2/lib/ruby/2.7.0/forwardable.rb:235:in `evaluate'
The line pbjs.getConfig() returns an object on actual website: http://grmdaily.com/
Seems to be issue in reducing received props.
Am I missing something?
A little more research:
The resulting object contains property getters, which when moving through the Ferrum code returns nil for properties that are function calls.
In Ferrum::Frame::Runtime#reduce_props:
props["result"].reduce(to) do |memo, prop|
next(memo) unless prop["enumerable"]
yield(memo, prop["name"], prop["value"]) # <-- prop["value"] is nil for getter function props
end
All values in props['result'] return true for #["enumerable"], so each one makes it to the yield call.
Here's what those keys and values look like:
(rdbg) props["result"][0]
{"name"=>"_debug",
"value"=>{"type"=>"boolean", "value"=>false},
"writable"=>true,
"configurable"=>true,
"enumerable"=>true,
"isOwn"=>true}
(rdbg) props["result"][1]
{"name"=>"debug",
"get"=>
{"type"=>"function",
"className"=>"Function",
"description"=>"get debug(){return this._debug}",
"objectId"=>"5453901104118849959.2.31"},
"set"=>
{"type"=>"function",
"className"=>"Function",
"description"=>"set debug(e){this._debug=e}",
"objectId"=>"5453901104118849959.2.32"},
"configurable"=>true,
"enumerable"=>true,
"isOwn"=>true}
props["result"].map{|prop| prop["name"]}
["_debug",
"debug",
"_bidderTimeout",
"bidderTimeout",
"_publisherDomain",
"publisherDomain",
"_priceGranularity",
"priceGranularity",
"_customPriceBucket",
"customPriceBucket",
"_mediaTypePriceGranularity",
"mediaTypePriceGranularity",
"_sendAllBids",
"enableSendAllBids",
"_useBidCache",
"useBidCache",
"_bidderSequence",
"bidderSequence",
"_timeoutBuffer",
"timeoutBuffer",
"_disableAjaxTimeout",
"disableAjaxTimeout",
"userSync",
"s2sConfig"]
props["result"].map{|prop| prop["value"]}
[{"type"=>"boolean", "value"=>false},
nil,
{"type"=>"number", "value"=>3000, "description"=>"3000"},
nil,
{"type"=>"string", "value"=>"https://grmdaily.com"},
nil,
{"type"=>"string", "value"=>"medium"},
nil,
{"type"=>"object", "className"=>"Object", "description"=>"Object", "objectId"=>"5453901104118849959.2.39"},
nil,
{"type"=>"object", "className"=>"Object", "description"=>"Object", "objectId"=>"5453901104118849959.2.41"},
nil,
{"type"=>"boolean", "value"=>true},
nil,
{"type"=>"boolean", "value"=>false},
nil,
{"type"=>"string", "value"=>"random"},
nil,
{"type"=>"number", "value"=>400, "description"=>"400"},
nil,
{"type"=>"boolean", "value"=>false},
nil,
{"type"=>"object", "className"=>"Object", "description"=>"Object", "objectId"=>"5453901104118849959.2.54"},
{"type"=>"object", "className"=>"Object", "description"=>"Object", "objectId"=>"5453901104118849959.2.55"}]
These nil values are being returned to the calling frame as values, where value["objectid"] raises.
reduce_props(object_id, {}) do |memo, key, value|
value = value["objectId"] ? handle_response(value) : value["value"]
memo.merge(key => value)
end
@route What should the resulting Ruby object look like when the result references a function as above? Is it as simple as adding a guard such as value && value['objectid'] to show a nil value?
For what it's worth, I checked how objects with getters/setters are handled in both master and released v0.11. This test passes for both. I was hoping it would raise the NoMethodError from above.
expect(browser.evaluate(<<~JS)).to eq({"_a" => "Class with Getter"})
new (class {
constructor(a) {
this._a = a;
}
get a() { return this._a }
})("Class with Getter")
JS
@umairkhalid598 In the meantime, if you're stuck, you could serialize as JSON to pass back and forth:
JSON.parse(browser.evaluate("JSON.stringify(pbjs.getConfig())"))