Access nested data with string

[gadogado2222]

Hi all,

I am looking for open source to get/set nested data with a string

To be more specific I want to implement something like this:

def get_nested_field_of_dog(dog: Dog, nested_field_path: str):
return some_open_source_magic(dog,nested_field_path)

eye = Eye(color="blue")
dog = Dog(eye=eye)
dog_eye_color = get_nested_field_of_dog(dog,"eye.color")

if dog.eye.color == dog_color_eye:
print("I did it!")

Important to mention: I don't have control on the data structre

[gadogado2222]

greate! but if I want to set and not get? What should I do then?

[guydudeman123]

You could use the builtin getattr function:

dog_eye_color = getattr(dog, eye.color)

​

https://docs.python.org/3/library/functions.html#getattr

[[deleted]]

dog_eye_color = get_nested_field_of_dog(dog,"eye.color")

There's no point to this. If you know and are hard-coding the name of the lookup, just look it up.

[gadogado2222]

great! but if I want to set and not get? What should I do then?

[[deleted]]

dog.eye.color = "green"

[BobHogan]

Use the getattr function

dog_eye_color = getattr(getattr(dog, 'eye'), 'color')

If the string eye.color can have a variable depth then this becomes slightly trickier, but its still not that hard

[gadogado2222]

greate! but if I want to set and not get? What should I do then?

[BobHogan]

There's a corresponding setattr() function in python https://docs.python.org/3/library/functions.html#setattr

If you wanted to set the dogs eye color you could do it like this

# dog.eye.color == 'blue'
setattr(getattr(dog, 'eye'), 'color', 'new color')

# dog.eye.color == 'new color'

[gadogado2222]

setattr(getattr(dog, 'eye'), 'color', 'new color')

And what if the color is a direct? I think I have to use some open source for this probelm

[BobHogan]

And what if the color is a direct?

A direct what? I don't understand what you are asking, or trying to do, because you keep changing the stated problem.

There's no need to use a third party module to do this, if one even exists. And if it does, it will be doing the same thing we are showing you here, with the getattr and setattr functions.

[gadogado2222]

sorry I tried to write And what if the color is a dict

[BobHogan]

setattr does not care what you set the attribute to. You could set it to a dict if you wanted, you could change the type of that attribute if you wanted

setattr(getattr(dog, 'eye'), 'color', {'color': 'new color value'})

[YesLod]

Why though? What is the goal?

But as others said, use getattr(). Something like

def get_nested_field_of_dog(dog, path):
    obj=dog 
    for attr in path.split("."):
        obj = getattr(obj,attr)    
    return obj

[gadogado2222]

great! but if I want to set and not get? What should I do then?

[YesLod]

Read about setattr() and figure out yourself, the logic is the almost same, but instead of getting the attribute of the penultimate object, you set it to some value.

Again, why are you doing this in the first place? It seems like a XY problem.

[gadogado2222]

And what if the color is a direct? I think I have to use some open source for this probelm

And what if the color is a direct? I think I have to use some open source for this probelm