handle duplicate shared strings

[davidskelly]

Trying to read an excel file not created by me, sharedString is null.

Unhandled exception:
Null check operator used on a null value
#0      Parser._parseCell (package:excel/src/parser/parse.dart:614:48)
#1      Parser._parseRow.<anonymous closure> (package:excel/src/parser/parse.dart:578:7)
#2      Iterable.forEach (dart:core/iterable.dart:366:35)
#3      Parser._parseRow (package:excel/src/parser/parse.dart:577:22)
#4      Parser._parseTable.<anonymous closure> (package:excel/src/parser/parse.dart:557:7)
#5      Iterable.forEach (dart:core/iterable.dart:366:35)
#6      Parser._parseTable (package:excel/src/parser/parse.dart:556:22)
#7      Parser._parseContent.<anonymous closure> (package:excel/src/parser/parse.dart:156:9)

This appears to be the case when xl/sharedStrings.xml contains duplicate entries, eg

<si>
        <t>Entry Here</t>
    </si>
<si>
        <t>Entry Here</t>
    </si>

A code change like value = sharedString == null ? null : TextCellValue.span(sharedString!.textSpan); allows the document to parse, but now fetching certain cells point to the incorrect index and will return the wrong text - basically a corrupted document. So this is not the correct fix.

When adding a shared string, adding it to the _list always, even if it's a duplicate, fixes the null pointer exception and fixes the text retrieval of the cells that were retrieving incorrect text values before.

Same as this issue: #435 #433
Related to these prs: #434 #436

[menghinidev]

Can we get an ETA on this? @justkawal @justraman

[menghinidev]

Please @justkawal @justraman give at least a feedback that you received the request.
There are several PRs on this matter waiting for your approval and code review.

[prcwak]

It works for me.
prcwak@d3ab813

[gonojuarez]

@davidskelly I created a fork of Flutter Excel. The name is excel_community you can find it here link