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 ,
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 <javascript:>>
> 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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