[Qgis-developer] QGIS API: change layer field length

[Voisard François]

Hi Romain, hi Devs,

My first post on the ML; followed it about 6 months for now... =:0)

Romain, if I've understood you right, I think your problem is not a QGIS but a Mapinfo problem: MapInfo accepts only a max. of 254 character per field [1]. 

So whatever the length is in your DB, a Mapinfo file will never store and display more than the 254 characters. We've got the same problem with Oracle/PostGIS data displayed using MapInfo ODBC connections.

Best regards,
François

[1] http://testdrive.mapinfo.com/techsupp/miprod.nsf/kbase_by_product/BC5DE25962BC57C285256278002FB800

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Message: 2
Date: Sun, 17 Jul 2011 14:23:48 -0700 (PDT)
From: romain <romain.riviere.974 at gmail.com>
Subject: [Qgis-developer] Re: QGIS API: change layer field length
To: qgis-developer at lists.osgeo.org
Message-ID: <1310937828326-6592720.post at n2.nabble.com>
Content-Type: text/plain; charset=us-ascii

Sorry, I think i haven't explained well what I want.

I know how to get my fields' lengths from SpatiaLite.

Here is what I've already done:
1/ create QgsvectorLayer from spatiaLite table : vlayer
2/ strore field's length in a python list: lengths

One of my text fields (FIELD1) have 300 characters....


What my problem is when i want to save the layer as mapinfo file with :

QgsVectorFileWritter.writteAsFromat(vlayer,........,mapinfo)

-> The mapinfo File is created but all the fields are truncated at 254
char.... So, I lost informations on FIELD1...

I've tried to set fields lengths for my layer, in order to avoid truncature,
but, it doesn't change anything:

fields=vlayer.dataProvider().fields()
for field in fields:
      fields[field].setLength(301)


Any hints ?

The only thing I need is to pass an option to Qgsvectorfilewritter to change
fields maximum characters...
Does anybody know how to do this directly with OGR ? (within python, of
course)

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