Question

I’m trying to substitue the channel name for AndroidManifest.xml to batch generate a groups of channel apk packages for release.

<meta-data android:value="CHANNEL_NAME_TO_BE_DETERMINED" android:name="UMENG_CHANNEL"/>
from an xml file.

The channel configs are saved in a config file, sth like:

channel_name    output_postfix  valid 
"androidmarket" "androidmarket" true

Here is what I tried:

manifest_original_xml_fh = open("../AndroidManifest_original.xml", "r")
manifest_xml_fh = open("../AndroidManifest.xml", "w")
pattern = re.compile('<meta-data\sandroid:value=\"(.*)\"\sandroid:name=\"UMENG_CHANNEL\".*')
for each_config_line in manifest_original_xml_fh:
    each_config_line = re.sub(pattern, channel_name, each_config_line) 
    print each_config_line

It replaces the whole <meta-data android:value="CHANNEL_NAME_TO_BE_DETERMINED" android:name="UMENG_CHANNEL"/> to androidmarket which is obviously not my need. Then I figured out the problem is that pattern.match(each_config_line) return a match result ,and one of the result group is “CHANNEL_NAME_TO_BE_DETERMINED”. I’ve also tried to give some replace implementation function, but still failed.

So, since I’ve successfully find the pattern, how can I replace the matched result group element correctly?

Answer 1

I think your misunderstanding is, everything that has been matched will be replaced. If you want to keep stuff from the pattern, you have to capture it and reinsert it in the replacement string.

Or match only what you want to replace by using lookaround assertions

Try this

pattern = re.compile('(?<=<meta-data\sandroid:value=\")[^"]+')
for each_config_line in manifest_original_xml_fh:
    each_config_line = re.sub(pattern, channel_name, each_config_line)

(?<=<meta-data\sandroid:value=\") is a positive lookbehind assertion, it ensures that this text is before, but does not match it (so it will not be replaced)

[^"]+ will then match anything that is not a "

See it here on Regexr