I have a vector layer tipor several polylines. 
I opened this layer in QGIS and exoportar to a spatial table in PostGIS. 
ST\_AsGeoJSON want to use the function to get the GeoJSON to draw on Google Maps. 
I used the select below: 

```
SELECT ST_AsGeoJSON (geom), Codlin 
   FROM "lines"; 

```

I noticed that in the result column st\_asgeojson few lines comes in white and records that return blank geom field of the table space is blank. 
I think some records of my table are not georeferenced. 
How can I fix this error?