LayermappingLink to this heading#Soláthraíonn an rang:class: LayerMapping bealach chun ábhar comhaid sonraí spásúla veicteora (m.sh. comhaid chruthach) a mhapáil i samhlacha GeoDjango.
\nD'fhás an fóntais seo as riachtanais phearsanta an údair chun deireadh a chur leis an athrá cód a chuaigh chun geoiméadraí agus réimsí a tharraingt as ciseal veicteora, ag tiontú go córas comhordaithe eile (m.sh. WGS84), agus ansin a chur isteach i samhail GeoDjango.
\n\n\nTeastaíonn foinse sonraí le tacaíocht ó GDAL uait, cosúil le comhaid chruthach (anseo táimid ag úsáid comhad cruth polygon simplí, test_poly.shp, le trí ghné):
>>> from django.contrib.gis.gdal import DataSource\n>>> ds = DataSource("test_poly.shp")\n>>> layer = ds[0]\n>>> print(layer.fields) # Exploring the fields in the layer, we only want the 'str' field.\n['float', 'int', 'str']\n>>> print(len(layer)) # getting the number of features in the layer (should be 3)\n3\n>>> print(layer.geom_type) # Should be 'Polygon'\nPolygon\n>>> print(layer.srs) # WGS84 in WKT\nGEOGCS["GCS_WGS_1984",\n DATUM["WGS_1984",\n SPHEROID["WGS_1984",6378137,298.257223563]],\n PRIMEM["Greenwich",0],\n UNIT["Degree",0.017453292519943295]]\nAnois sainmhínímid ár samhail Django comhfhreagrach (déan cinnte go n-úsáidtear: djadmin: migrate):
\nfrom django.contrib.gis.db import models\n\n\nclass TestGeo(models.Model):\n name = models.CharField(max_length=25) # corresponds to the 'str' field\n poly = models.PolygonField(srid=4269) # we want our model in a different SRID\n\n def __str__(self):\n return "Name: %s" % self.name\nÚsáid: aicme: LayerMapping chun na gnéithe go léir a bhaint agus iad a chur sa bhunachar sonraí:
>>> from django.contrib.gis.utils import LayerMapping\n>>> from geoapp.models import TestGeo\n>>> mapping = {\n... "name": "str", # The 'name' model field maps to the 'str' layer field.\n... "poly": "POLYGON", # For geometry fields use OGC name.\n... } # The mapping is a dictionary\n>>> lm = LayerMapping(TestGeo, "test_poly.shp", mapping)\n>>> lm.save(verbose=True) # Save the layermap, imports the data.\nSaved: Name: 1\nSaved: Name: 2\nSaved: Name: 3\nHere, LayerMapping transformed the three geometries from the shapefile\nin their original spatial reference system (WGS84) to the spatial reference\nsystem of the GeoDjango model (NAD83). If no spatial reference system is\ndefined for the layer, use the source_srs keyword with a\nSpatialReference object to specify one.
Sraith Maping APILink to this heading#Is iad seo a leanas na hargóintí agus na heochairfhocail a d'fhéadfaí a úsáid le linn rudaí Layermapping` a chur isteach.
\nArgóint | \nCur síos | \n
|---|---|
``Samhail `` | \nAn tsamhail gheografach, ní sampla. | \n
| \nThe path to the OGR-supported data source file\n(e.g., a shapefile). Also accepts\n | \n
| \nFoclóir: is teaghráin iad na heochracha a fhreagraíonn don réimse samhail, agus freagraíonn luachanna d'ainmneacha réimse teaghrán don ghné OGR, nó más réimse samhail is geografach é ansin ba chóir go bhfreagródh sé do chineál geoiméadrachta OGR, m.sh., | \n
Argóintí Eochair | \n\n |
|---|---|
| \nInnéacs an chiseal le húsáid ón bhFoinse Sonraí (réamhshocraithe go 0) | \n
| \nUse this to specify the source SRS manually (for\nexample, some shapefiles don't come with a | \n
``ionchódú `` | \nSpecifies the character set encoding of the strings\nin the OGR data source. For example, | \n
| \nD'fhéadfadh sé a bheith | \n
| \nSetting this to False will disable coordinate\ntransformations. In other words, geometries will\nbe inserted into the database unmodified from their\noriginal state in the data source. | \n
| \nSetting this to the name, or a tuple of names,\nfrom the given model will create models unique\nonly to the given name(s). Geometries from\neach feature will be added into the collection\nassociated with the unique model. Forces\nthe transaction mode to be | \n
| \nSocraíonn an bunachar sonraí le húsáid agus sonraí spásúla á iompórtá Is é réamhshocraithe ``'default' ``. | \n
The save() method also accepts keywords. These keywords are\nused for controlling output logging, error handling, and for importing\nspecific feature ranges.
Argóintí Eochairfhocal | \nCur síos | \n
|---|---|
| \nMay be set with a slice or tuple of\n(begin, end) feature ID's to map from\nthe data source. In other words, this\nkeyword enables the user to selectively\nimport a subset range of features in the\ngeographic data source. | \n
| \nWhen this keyword is set, status information\nwill be printed giving the number of features\nprocessed and successfully saved. By default,\nprogress information will be printed every 1000\nfeatures processed, however, this default may\nbe overridden by setting this keyword with an\ninteger for the desired interval. | \n
| \nDe réir réamhshocraithe, clóitear fógraí earráide neamh-mharfach chuig sys.stdout`, ach féadfar an eochairfhocal seo a shocrú chun na fógraí seo a dhíchumasú. | \n
| \nMá shocraítear é le sláimhir, tarlóidh idirbhearta ag gach eatramh céim. Mar shampla, má tharlódh sé | \n
| \nStatus information will be written to this file\nhandle. Defaults to using | \n
``docht `` | \nExecution of the model mapping will cease upon\nthe first error encountered. The default value\n( | \n
| \nMá shocraítear é, clófar faisnéis ina dhiaidh sin gach samhail sábháil a fhorghníomhú ar an mbunachar sonraí. | \n
As noted in the warning at the top of this section, Django stores all SQL\nqueries when DEBUG=True. Set DEBUG=False in your settings, and this\nshould stop excessive memory use when running LayerMapping scripts.
max_allowed_packetLink to this heading#Má thagann tú ar an earráid seo a leanas agus tú ag úsáid LayerMapping agus MySQL:
OperationalError: (1153, "Got a packet bigger than 'max_allowed_packet' bytes")\nThen the solution is to increase the value of the max_allowed_packet\nsetting in your MySQL configuration. For example, the default value may\nbe something low like one megabyte -- the setting may be modified in MySQL's\nconfiguration file (my.cnf) in the [mysqld] section:
max_allowed_packet = 10M\n