pycbc: A Python interface to the Christmas Bird Count database |  |
pycbc: A Python interface to the Christmas Bird Count database | |
This section of the pycbc.py file
describes the mapping between objects and database tables, and
the relations between the tables.
A number of new attributes are added to the mapped classes in this section:
| Table | Attribute | Function |
|---|---|---|
nations
|
.regions
|
Iterates over the Region instances for
this nation.
|
regions
|
.nation
|
The related Nation instance for this
region.
|
.circles
|
Iterates over the Circle instances that
are all or partly within this region.
| |
.cir_regs
|
Iterates over the CirReg instances that
are related to this region. This attribute is
necessary because the CirReg instance
has a column reg_pos that is not found
in either the circles or region table.
| |
cir_reg
|
.region
|
The related Region instance for this
row.
|
.circle
|
The related Circle instance for this
row.
| |
physios
|
.circles
| Iterates over the circles that are related to this stratum. |
.cir_physios
|
Iterates over the CirPhysio instances
for this stratum.
| |
cir_physio
|
.circle
|
The related Circle.
|
.physio
|
The related Physio.
| |
circles
|
.regions
|
Iterates over the Region instances for
this circle.
|
.cir_regs
|
Iterates over the CirReg instances for
this circle.
| |
.physios
|
Iterates over the Physio instances for
this circle.
| |
.cir_physios
|
Iterates over the CirPhysio instances
for this circle.
| |
.efforts
|
Iterates over the Effort instances for
this circle.
|
The first table to be mapped is the nations table, which has a one-to-many relation with the regions table.
#================================================================
# Mapper configuration
#----------------------------------------------------------------
orm.mapper(Nation, nations_table,
properties={
'regions': orm.relation(Region, backref='nation')})
The regions table has a many-to-many relation
to the circles table, through the secondary table
cir_reg.
orm.mapper(Region, regions_table,
properties={
'cir_regs': orm.relation(CirReg, backref='region'),
'circles': orm.relation(Circle,
secondary=cir_reg_table, backref='regions')})
orm.mapper(CirReg, cir_reg_table)
The physios table has a many-to-many relation
with the circles table, through the secondary
table cir_physio.
orm.mapper(Physio, physios_table,
properties={
'circles': orm.relation(Circle,
secondary=cir_physio_table, backref='physios'),
'cir_physios': orm.relation(CirPhysio, backref='physio')})
orm.mapper(CirPhysio, cir_physio_table)
The circles table has a one-to-many relation with the efforts table. (Its two many-to-many relations were set up above.)
orm.mapper(Circle, circles_table,
properties={
'cir_regs': orm.relation(CirReg, backref='circle'),
'cir_physios': orm.relation(CirPhysio, backref='circle'),
'efforts': orm.relation(Effort, backref='circle')})
The one-to-many relation between the effort table and the censuses table is mapped here.
orm.mapper(Effort, efforts_table,
properties={
'censuses': orm.relation(Census, backref='effort')})
orm.mapper(Census, censuses_table)