[Qgis-developer] WktExport plugin for QGIS

[Even Rouault]

Le mardi 25 août 2015 16:22:13, Geo DrinX a écrit :
> Side remark. Your plugin probably makes it a bit more convenient, but you
> 
> > can
> > already get the geometries in WKT format with "Save as", select CSV and
> > enter
> > GEOMETRY=AS_WKT as layer creation option (cf
> > http://www.gdal.org/drv_csv.html)
> 
> Touche' ,  Even  :)
> 
> I do not know that is possible to do the same with save as...   :(
> 
> BTW,  great !    There is some documentation for this ?   I will browse
> QGIS manuals.
> 
> Sure, my method is more immediate, and more convenient for my own use.
> For the rest of the world, I agree with you :   a generic user, can use
> "Save as..."   CSV  and enter  "GEOM=ASWKT"
> and... it does not work !  What is the correct syntax ?  I do not
> remember:  I need to try again... perhaps:  "GEOMETRY=ASWKT".   No, it do
> not work again... etcetera.

Indeed, the good news is that with GDAL 2.0, OGR drivers now have metadata. So  
instead/in addition of a free text zone, the list of options could now 
potentially be automatically generated by inspecting driver metadata

$ ogrinfo --format csv
Format Details:
  Short Name: CSV
  Long Name: Comma Separated Value (.csv)
  Supports: Vector
  Extension: csv
  Help Topic: drv_csv.html
  Supports: Open() - Open existing dataset.
  Supports: Create() - Create writeable dataset.
  Supports: Virtual IO - eg. /vsimem/
  Creation Field Datatypes: Integer Integer64 Real String Date DateTime Time

<CreationOptionList>
  <Option name="GEOMETRY" type="string-select" description="how to encode 
geometry fields">
    <Value>AS_WKT</Value>
  </Option>
</CreationOptionList>


<LayerCreationOptionList>
  <Option name="SEPARATOR" type="string-select" description="field separator" 
default="COMMA">
    <Value>COMMA</Value>
    <Value>SEMICOLON</Value>
    <Value>TAB</Value>
    <Value>SPACE</Value>
  </Option>
  <Option name="LINEFORMAT" type="string-select" description="end-of-line 
sequence" default="LF">
    <Value>CRLF</Value>
    <Value>LF</Value>
  </Option>
  <Option name="GEOMETRY" type="string-select" description="how to encode 
geometry fields">
    <Value>AS_WKT</Value>
    <Value>AS_XYZ</Value>
    <Value>AS_XY</Value>
    <Value>AS_YX</Value>
  </Option>
  <Option name="CREATE_CSVT" type="boolean" description="whether to create a 
.csvt file" default="NO" />
  <Option name="WRITE_BOM" type="boolean" description="whether to write a 
UTF-8 BOM prefix" default="NO" />
  <Option name="GEOMETRY_NAME" type="string" description="Name of geometry 
column. Only used if GEOMETRY=AS_WKT" default="WKT" />
</LayerCreationOptionList>

<OpenOptionList>
  <Option name="MERGE_SEPARATOR" type="boolean" description="whether to merge 
consecutive separators" default="NO" />
  <Option name="AUTODETECT_TYPE" type="boolean" description="whether to guess 
data type from first bytes of the file" default="NO" />
  <Option name="KEEP_SOURCE_COLUMNS" type="boolean" description="whether to 
add original columns whose guessed data type is not String. Only used if 
AUTODETECT_TYPE=YES" default="NO" />
  <Option name="AUTODETECT_WIDTH" type="string-select" description="whether to 
auto-detect width/precision. Only used if AUTODETECT_TYPE=YES" default="NO">
    <Value>YES</Value>
    <Value>NO</Value>
    <Value>STRING_ONLY</Value>
  </Option>
  <Option name="AUTODETECT_SIZE_LIMIT" type="int" description="number of bytes 
to inspect for auto-detection of data type. Only used if AUTODETECT_TYPE=YES" 
default="1000000" />
  <Option name="QUOTED_FIELDS_AS_STRING" type="boolean" description="Only used 
if AUTODETECT_TYPE=YES. Whether to enforce quoted fields as string fields." 
default="NO" />
  <Option name="X_POSSIBLE_NAMES" type="string" description="Comma separated 
list of possible names for X/longitude coordinate of a point." />
  <Option name="Y_POSSIBLE_NAMES" type="string" description="Comma separated 
list of possible names for Y/latitude coordinate of a point." />
  <Option name="Z_POSSIBLE_NAMES" type="string" description="Comma separated 
list of possible names for Z/elevation coordinate of a point." />
  <Option name="GEOM_POSSIBLE_NAMES" type="string" description="Comma 
separated list of possible names for geometry columns." default="WKT" />
  <Option name="KEEP_GEOM_COLUMNS" type="boolean" description="whether to add 
original x/y/geometry columns as regular fields." default="YES" />
  <Option name="HEADERS" type="string-select" description="Whether the first 
line of the file contains column names or not" default="AUTO">
    <Value>YES</Value>
    <Value>NO</Value>
    <Value>AUTO</Value>
  </Option>
</OpenOptionList>


> 
> :)
> 
> Yes, I think my plugin can be useful to all of us "QGIS dummies"    :)
> 
> If you think, I can insert a message that explains:  "You can also use
> 'Save as... CSV    GEOMETRY=AS_WKT'
> 
> :)
> 
> Of course, I am joking.
> 
> 
> Happy holidays
> 
> 
> Roberto

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