FileWriter.seek(0) does not actually seek to the beginning of the file.
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Key: CB-472
URL: https://issues.apache.org/jira/browse/CB-472
Project: Apache Callback
Issue Type: Bug
Components: CordovaJS
Affects Versions: 1.5.0, 1.4.0, 1.3.0, 1.2.0, 1.1.0, 1.0.0
Reporter: Simon MacDonald
Assignee: Simon MacDonald
Tom Jenkins [email protected] via googlegroups.com
Hi all,
Not sure I'm going about this the right way, and sorry if it's been covered (I
did do a prior search), but anyway. I'm writing to a csv file using phonegap,
to record 'hits' on different parts of an app. Let's say the columns are
something like Section level 1, Section level 2, Page, Num. views.
Obviously I need to read in the file each time (I suppose I could store the
data in a JS array and write periodically, but anyway) to check whether
the'hit' that has just occurred needs to increment the view count on an
existing row, or add a new row (i.e. has the section been visited before or
not). This is all fine, dandy and working. I then need to calculate the new
contents of the file and write it back. It's simplest to just overwrite the
entire contents, so I try:
writer.seek(0);
writer.write(data);
What actually happens is the data gets appended instead. I found this is
because when I call writer.seek(0), it's not actually seeking, because of this
check in FileWriter.prototype.seek:
if (!offset) {
return;
}
I assume that the check is to catch offset values that are for some reason null
or false (unchecked return of a function call or something). However, this
obviously means that seek(0) will never seek, because the check sees the 0 as
boolean false. To get my code to work, I've simply changed the condition to:
if (!offset && offset != 0)
I could have used (offset === false) , but that wouldn't catch null values.
Anyone know if this is a bug, or whether I'm misunderstanding something and it
is intended behaviour?
Another solution would have been to create a new fileWriter object each time,
but somehow I don't think that was the best way to go ;)
Thanks
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