Query methods¶
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class
pg.Query¶
The Query object returned by Connection.query() and
DB.query() provides the following methods for accessing
the results of the query:
getresult – get query values as list of tuples¶
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Query.getresult()¶ Get query values as list of tuples
Returns: result values as a list of tuples
Return type: list
Raises: - TypeError – too many (any) parameters
- MemoryError – internal memory error
This method returns the list of the values returned by the query.
More information about this result may be accessed using
Query.listfields(), Query.fieldname()
and Query.fieldnum() methods.
Note that since PyGreSQL 5.0 this will return the values of array type columns as Python lists.
dictresult – get query values as list of dictionaries¶
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Query.dictresult()¶ Get query values as list of dictionaries
Returns: result values as a list of dictionaries
Return type: list
Raises: - TypeError – too many (any) parameters
- MemoryError – internal memory error
This method returns the list of the values returned by the query with each tuple returned as a dictionary with the field names used as the dictionary index.
Note that since PyGreSQL 5.0 this will return the values of array type columns as Python lists.
namedresult – get query values as list of named tuples¶
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Query.namedresult()¶ Get query values as list of named tuples
Returns: result values as a list of named tuples
Return type: list
Raises: - TypeError – too many (any) parameters
- TypeError – named tuples not supported
- MemoryError – internal memory error
This method returns the list of the values returned by the query with each row returned as a named tuple with proper field names.
Column names in the database that are not valid as field names for named tuples (particularly, names starting with an underscore) are automatically renamed to valid positional names.
Note that since PyGreSQL 5.0 this will return the values of array type columns as Python lists.
New in version 4.1.
listfields – list fields names of previous query result¶
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Query.listfields()¶ List fields names of previous query result
Returns: field names Return type: list Raises: TypeError – too many parameters
This method returns the list of names of the fields defined for the query result. The fields are in the same order as the result values.
fieldname, fieldnum – field name/number conversion¶
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Query.fieldname(num)¶ Get field name from its number
Parameters: num (int) – field number
Returns: field name
Return type: str
Raises: - TypeError – invalid connection, bad parameter type, or too many parameters
- ValueError – invalid field number
This method allows to find a field name from its rank number. It can be useful for displaying a result. The fields are in the same order as the result values.
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Query.fieldnum(name)¶ Get field number from its name
Parameters: name (str) – field name
Returns: field number
Return type: int
Raises: - TypeError – invalid connection, bad parameter type, or too many parameters
- ValueError – unknown field name
This method returns a field number from its name. It can be used to build a function that converts result list strings to their correct type, using a hardcoded table definition. The number returned is the field rank in the result values list.
