CODEWITHSUNDEEP
pythondjangojsongeodjango
Caustic
Caustic

Reputation: 979

json to geoDjango model

I am building a database using Django, geodjango and postgresql of field data. The data includes lats and lons. One of the tasks I have is to ingest data that has already been collected. I would like to use .json file to define the metadata and write some code to batch process some json files.

What I have so far is, a model:

class deployment(models.Model):                                                                          
    '''                                                                                                  
    @brief This is the abstract deployment class.                                                        
        '''                                                                                                  
        startPosition=models.PointField()                                                                    
        startTimeStamp=models.DateTimeField()                                                                
        endTimeStamp=models.DateTimeField()                                                                  
        missionAim=models.TextField()                                                                        
        minDepth=models.FloatField() # IT seems there is no double in Django                                 
        maxDepth=models.FloatField()                                                                         



class auvDeployment(deployment):                                                                         
    '''                                                                                                  
    @brief AUV meta data                                                                                 
    '''                                                                                                  
    #==================================================#                                                 
    # StartPosition : <point>                                                                            
    # distanceCovered : <double>                                                                         
    # startTimeStamp : <dateTime>                                                                        
    # endTimeStamp : <dateTime>                                                                          
    # transectShape : <>                                                                                 
    # missionAim : <Text>                                                                                
    # minDepth : <double>                                                                                
    # maxDepth : <double>                                                                                
    #--------------------------------------------------#                                                 
    # Maybe need to add unique AUV fields here later when                                                
    # we have more deployments                                                                           
    #==================================================#                                                 

    transectShape=models.PolygonField()                                                                  
    distanceCovered=models.FloatField()

And I function I want to use to ingest the data

@staticmethod                                                                                        
def importDeploymentFromFile(file):                                                                  
    '''                                                                                              
    @brief This function reads in a metadta file that includes campaign information. Destinction between deployment types is made on the fine name.  <type><deployment>.<supported text> auvdeployment.json 
    @param file The file that holds the metata data.  formats include .json todo:-> .xml .yaml       
    '''                                                                                              
    catamiWebPortal.logging.info("Importing metadata from " + file)                                  
    fileName, fileExtension = os.path.splitext(file)                                                 

    if fileExtension == '.json':                                                                     
        if os.path.basename(fileName.upper()) == 'AUVDEPLOYMENT':                                    
            catamiWebPortal.logging.info("Found valid deployment file")                              
            data = json.load(open(file))                                                             
            Model = auvDeployment(**data)                                                            
            Model.save()

And the file I am trying to read in this 

{
"id":1,
"startTimeStamp":"2011-09-09 13:20:00",
"endTimeStamp":"2011-10-19 14:23:54",
"missionAim":"for fun times, call luke",
"minDepth":10.0,
"maxDepth":20.0,
"startPosition":{{"type": "PointField", "coordinates": [ 5.000000, 23.000000 ] }}, 
"distanceCovered":20.0
}

The error that I am getting is this 

TypeError: cannot set auvDeployment GeometryProxy with value of type: <type 'dict'>

If I remove the geo types from the model and file. It will read the file and populate the database table.

I would appreciate any advice one how I am parse the datafile with the geotypes.

Thanks

Upvotes: 1

Views: 2361

Answers (3)

The Brofessor
The Brofessor

Reputation: 2401

A quick fix would be to use the GEOs API in geoDjango to change the startPosition field from geoJson format to a GEOSGeometry object before you save the model. This should allow it to pass validation.

Include the GEOSGeometry function from Django with:

from django.contrib.gis.geos import GEOSGeometry
...

Model = auvDeployment(**data)
Model.startPosition = GEOSGeometry(str(Model.startPosition))
Model.save()

The GEOS API can construct objects from a GeoJSON format, as long as you make it a string first. As it stands, you are loading it as a dictionary type instead of a string.

Upvotes: 2

Caustic
Caustic

Reputation: 979

Okay the solution is as follows. The file format is not the geoJSON file format, it's the geos format. The .json file should be as follows.

{
"id": 1,
"startTimeStamp": "2011-10-19 10:23:54",
"endTimeStamp":"2011-10-19 14:23:54",
"missionAim": "for fun times, call luke",
"minDepth":10.0,
"maxDepth":20.0,
"startPosition":"POINT(-23.15 113.12)", 
"distanceCovered":20,
"transectShape":"POLYGON((-23.15 113.12, -23.53 113.34, -23.67 112.9, -23.25 112.82, -23.15 113.12))"   
}

Not the StartPosition syntax has changed.

Upvotes: 1

Constantinius
Constantinius

Reputation: 35069

I suggest you use the default command for loading fixtures: loaddata

python manage.py loaddata path/to/myfixture.json ...

The structure of your json would have to be slighty adjusted, but you could make a simple dumpdata to see how the structure should look like.

Upvotes: 0

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