Hi Justin ,
cPickle can deserialize pymel node , and like eval it can't convert back if
the node not exists .
Thank you ,
在 2019年5月3日星期五 UTC+8上午3:40:51，Justin Israel写道：
>
>
>
> On Fri, May 3, 2019, 1:06 AM zhen huang <qee...@gmail.com <javascript:>>
> wrote:
>
>> Hi Justin ,
>>
>> Thank you ! I've tried the json even can't dumps the pymel node data .
>> This is why I looked for the eval solution .
>> Please check the error out :
>> Error: TypeError: file C:\Program
>> Files\Autodesk\Maya2017\bin\python27.zip\json\encoder.py line 184:
>> nt.Transform(u'pSphere2') is not JSON serializable
>>
>> Thanks and Regards ,
>>
>
> Convert the PyMel node into a fullpath string and store that. When you
> deserialize it back to a dict, you can convert the full path back into a
> PyMel node.
>
> Alternatively you may try using the cPickle module as it may be able
> serialize PyMel nodes. Probably better that you just use the full path
> though.
>
>
>> 在 2019年5月2日星期四 UTC+8下午6:47:45，Justin Israel写道：
>>>
>>>
>>>
>>> On Thu, May 2, 2019, 9:24 PM Zhen Huang <qeej...@gmail.com> wrote:
>>>
>>>> Hi ,
>>>>
>>>> I have a question about python build-in function 'eval ' , please check
>>>> out the example code below :
>>>>
>>>> ## create a polySphere , default name : 'pSphere1'
>>>>
>>>> import pymel.core as pm
>>>> from pymel.core import nt
>>>>
>>>> # initialize a pymel transform node
>>>> pymelShpere = pm.PyNode('pSphere1')
>>>> # put it to a dict
>>>> testDict = {0:pymelShpere}
>>>> # convert it to str which can be stored as string in file basic data
>>>> strMark = str(testDict)
>>>>
>>>> # now read it back , if scene has the pShere1 , it will work perfectly
>>>> newDict = eval(strMark)
>>>>
>>>> # now delete the pShpere1 , and try to convert data to dict , failed
>>>> because the pymel nt will try to initialize the string 'pShere1' to pymel
>>>> node
>>>> newDict =eval(strMark)
>>>>
>>>>
>>>> My question : if I have lots of nodes store in a string data which
>>>> convert from dict , is there a way to just make it out , just ignore error
>>>> part or if node not exists it just convert from nt to string name ?
>>>> if pSphere2 not exist then return
>>>>
>>>> {0:nt.Transform('pSphere1'), 1:'pSphere2' }
>>>>
>>>>
>>>>
>>>> Any idea is very much welcome , big thanks !!!
>>>>
>>>
>>> I would advise staying away from the eval() approach. Not only is it
>>> going to be inflexible for your current goal, it also can cause unwanted
>>> execution of arbitrary logic. A random code snippet that deletes files
>>> could be set on a node and your code would blindly execute it as your own
>>> user. You don't want random code being evaluated like that.
>>>
>>> A better approach would be to use a proper serialisation format like
>>> json or pickle (protocol version 1 for ascii format). This would allow you
>>> to read the data back into a dictionary and then evaluate each value and
>>> filter what does and does not exist in the scene.
>>>
>>>
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