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I spent a long time now trying to figure this myself with the help of other questions but failed so I REALLY need to ask this again
I have the following object in ruby
(...)
:follow_request_sent:
:notifications:
:coordinates:
:place:
:contributors:
:favorite_count: 0
:entities:
:hashtags:
- :text:
:indices:
(...)
This is object X. What I want to do is check if x.place exists. I've tried barely EVERYTHING. any, ?, include?, with [hash], defined?, (...) but it ALWAYS throws an error "undefined method" when trying to access the property, whether it exists or not. It NEVER works and I don't understand why. This is twitter API btw. Does anyone imagine why? Please do not point me to another answers because basically they all failed.
877
We can check if a property exists in the object by checking if property !== undefined . In this example, it would return true because the name property does exist in the developer object.
Using myObject. hasOwnProperty('prop') is a great way of accessing the Object's keys directly, which does not look into the Object's prototype - hooray, this is great for specific use cases. hasOwnProperty returns a Boolean for us on whether a property exists.
The static Reflect.has() method works like the in operator as a function. If the property does not exist on the object, it will return the string undefined. Else it will return the appropriate property type.
To check if a property exists in an object in TypeScript: Mark the specific property as optional in the object's type. Use a type guard to check if the property exists in the object. If accessing the property in the object does not return a value of undefined , it exists in the object.
If you want to see if there is such a method:
x.respond_to?(:place)
If you want to see if there is an instance variable:
x.instance_variable_defined?(:@place)
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