mholt/PapaParse

meta.cursor value is incorrect if you use parser.pause() and parser.resume()

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#321 opened on Jul 7, 2016

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 (10 comments) (4 reactions) (0 assignees)JavaScript (11,877 stars) (1,157 forks)batch import
help wanted

Description

I'm trying to make use of meta.cursor to display a progress bar. The following example works fine:

Papa.parse(file, {
    step: function(results, parser){
         // This gives expected result for cursor
         console.info(result.meta.cursor);
     }
}

Unfortunately, if I make use of parser.pause() and parser.resume() the value for meta.cursor is incorrect. Instead of getting an incrementing value I end up getting a seemingly random number that stays fairly constant and does not add up to the total file size if I sum it up.

Papa.parse(file, {
     step: function(results, parser){
             // This does not give the correct value for cursor
             console.info(result.meta.cursor);
             parser.pause();
             parser.resume();
      }
}

I need to pause the stream because I send the data in chunks to the server for processing and wait for the server to finish before sending the next chunk of data.

Thank you!

Contributor guide

Tech stack
javascript
Domain
data
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
JavaScriptPapaParse APIasync programming
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50
Research direction
Investigate the implementation of meta.cursor in PapaParse's streaming parser (likely in PapaParse.js). The cursor value is calculated based on the current character position in the file. When pause/resume is called, the internal state might not be updated correctly. Look at the step callback and how the parser handles pausing to fix the incremental cursor. Check existing comments in the issue for potential clues.
meta.cursor value is incorrect if you use parser.pause() and parser.resume() · mholt/PapaParse#321 | Good First Issue