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__version__ = "$Revision$" |
__version__ = "$Revision$" |
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import dbflib |
import dbflib |
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from Thuban.common import * |
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# the field types supported by a Table instance. |
# the field types supported by a Table instance. |
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FIELDTYPE_INT = "int" |
FIELDTYPE_INT = "int" |
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Currently this is basically just a wrapper around dbflib. |
Currently this is basically just a wrapper around dbflib. |
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""" |
""" |
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# Implementation strategy regarding writing to a DBF file: |
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# |
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# Most of the time Thuban only needs to read from a table and it is |
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# important that Thuban can work with read-only files. Therefore the |
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# DBF file is opened only for reading initially. Only when |
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# write_record is called we try to open the DBF file for writing as |
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# well. If that succeeds the dbf read/write DBF file will be used |
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# for all IO afterwards. |
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# |
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# It's important to use the same DBF file object for both reading |
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# and writing to make sure that reading a records after writing |
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# returns the new values. With two separate objects this wouldn't |
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# work because a DBF file object buffers some data |
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def __init__(self, filename): |
def __init__(self, filename): |
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self.filename = filename |
self.filename = filename |
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self.dbf = dbflib.DBFFile(filename) |
self.dbf = dbflib.DBFFile(filename) |
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# If true, self.dbf is open for writing. |
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self._writable = 0 |
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def Destroy(self): |
def Destroy(self): |
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self.dbf.close() |
self.dbf.close() |
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self.dbf = None |
self.dbf = None |
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type = dbflib_fieldtypes[type] |
type = dbflib_fieldtypes[type] |
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return type, name, width, prec |
return type, name, width, prec |
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def field_info_by_name(self, fieldName): |
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count = self.field_count() |
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for i in range(count): |
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info = self.field_info(i) |
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if info[1] == fieldName: |
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return info |
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return None |
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def read_record(self, record): |
def read_record(self, record): |
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"""Return the record no. record as a dict mapping field names to values |
"""Return the record no. record as a dict mapping field names to values |
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""" |
""" |
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return self.dbf.read_record(record) |
return self.dbf.read_record(record) |
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def write_record(self, record, values): |
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"""Write the values into the record |
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The values parameter may either be a dictionary or a sequence. |
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If it's a dictionary the keys must be the names of the fields |
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and their value must have a suitable type. Only the fields |
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actually contained in the dictionary are written. Fields for |
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which there's no item in the dict are not modified. |
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If it's a sequence, all fields must be present in the right |
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order. |
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""" |
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if not self._writable: |
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new_dbf = dbflib.DBFFile(self.filename, "r+b") |
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self.dbf.close() |
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self.dbf = new_dbf |
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self._writable = 1 |
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self.dbf.write_record(record, values) |
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self.dbf.commit() |
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