[Tutor] How to Compare rpm version using Python Script

[Alan Gauld]

On 02/12/2019 13:55, Asad wrote:

> I am trying to use Json to serialize the data 
...
> It gives a list of rpm separated by space . How can I convert to json so
> that I can then make it a python dictionary object dictOne ?

I'm not sure why you think you need JSON? Can you not just save the
space separated data into a text file and process that line by line?
I'm not sure how JSON helps?

You can then read the lines back and use line.split() to get the
individual fields in a list.

> dictTwo is a required list of rpm's which is to be checked  .

If it is a list why is it called a dict?
It is always better to avoid putting types into variable names.
Better to describe the variables purpose.

> for rpmOne in dictOne:
>     for rpmTwo in dictTwo:
>         if rpmOne["name"] == rpmTwo["name"]:
>            if rpmOne["arch"] == "x86_64" :
>             if rpmOne["version"] >= rpmTwo["version"] :
>                #print rpm["name"],rpm["arch"],rpm["version"], "Installed"
>                Installedrpm.append([rpm["name"],rpm["arch"],rpm["version"]])
>             else :
>               #print rpm["name"],rpm["arch"],rpm["version"] , "Version is
> less than required"
>               Installedrpm.append([rpm["name"],rpm["arch"],rpm["version"]])
>            elif rpm["arch"] == "i686" :
>             if rpm["version"] >= rpmTwo["version"] :
>                #print rpm["name"],rpm["arch"],rpm["version"], "Installed"
>               Installedrpm.append([rpm["name"],rpm["arch"],rpm["version"]])
>             else :
>               #print rpm["name"],rpm["arch"],rpm["version"] , "Version is
> less than required"
>               Installedrpm.append([rpm["name"],rpm["arch"],rpm["version"]])
>    else:
>        continue
> else :
> 
>        NotInstalledrpm.append([rpm["name"],rpm["arch"],rpm["version"]])

This confuses the actual tests with the outcome actions. It is probably
better to put the tests in a comparison function (or set of functions).
Better still create a class from the line data and write some comparison
operators as methods. Then you can do something like:

rpm1 = RPM(file.readline().strip().split())
rpm2 = RPM(file.readline().strip().split())

if rpm1 > rpm2: # save one of them somewhere...
elif rpm1 < rpm2   # deal with the opposite cae
else: # deal with the equality case.

> for install in Installedrpm :
>     print install[0],install[1],install[2]

Would become
for rpm in installed_rpms:
    print rpm   # using the __str__ method of RPM class.

> Please advice if there could be simpler or smarter way to achieve this .

Probably not much simpler to code but a lot simpler to
read the final logic

-- 
Alan G
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