Kaydet (Commit) 44850ea1 authored tarafından Georg Brandl's avatar Georg Brandl

Backport rev 51866-51868 from trunk (sqlite3 documentation fixes).

üst af22c52f
...@@ -146,8 +146,8 @@ committed. The \var{timeout} parameter specifies how long the connection should ...@@ -146,8 +146,8 @@ committed. The \var{timeout} parameter specifies how long the connection should
wait for the lock to go away until raising an exception. The default for the wait for the lock to go away until raising an exception. The default for the
timeout parameter is 5.0 (five seconds). timeout parameter is 5.0 (five seconds).
For the \var{isolation_level} parameter, please see \member{isolation_level} For the \var{isolation_level} parameter, please see the \member{isolation_level}
\ref{sqlite3-Connection-IsolationLevel} property of \class{Connection} objects. property of \class{Connection} objects in section~\ref{sqlite3-Connection-IsolationLevel}.
SQLite natively supports only the types TEXT, INTEGER, FLOAT, BLOB and NULL. If SQLite natively supports only the types TEXT, INTEGER, FLOAT, BLOB and NULL. If
you want to use other types, like you have to add support for them yourself. you want to use other types, like you have to add support for them yourself.
...@@ -197,7 +197,7 @@ This can be used to build a shell for SQLite, like in the following example: ...@@ -197,7 +197,7 @@ This can be used to build a shell for SQLite, like in the following example:
\verbatiminput{sqlite3/complete_statement.py} \verbatiminput{sqlite3/complete_statement.py}
\end{funcdesc} \end{funcdesc}
\begin{funcdesc}{}enable_callback_tracebacks{flag} \begin{funcdesc}{enable_callback_tracebacks}{flag}
By default you will not get any tracebacks in user-defined functions, By default you will not get any tracebacks in user-defined functions,
aggregates, converters, authorizer callbacks etc. If you want to debug them, aggregates, converters, authorizer callbacks etc. If you want to debug them,
you can call this function with \var{flag} as True. Afterwards, you will get you can call this function with \var{flag} as True. Afterwards, you will get
...@@ -212,13 +212,14 @@ A \class{Connection} instance has the following attributes and methods: ...@@ -212,13 +212,14 @@ A \class{Connection} instance has the following attributes and methods:
\label{sqlite3-Connection-IsolationLevel} \label{sqlite3-Connection-IsolationLevel}
\begin{memberdesc}{isolation_level} \begin{memberdesc}{isolation_level}
Get or set the current isolation level. None for autocommit mode or one of Get or set the current isolation level. None for autocommit mode or one of
"DEFERRED", "IMMEDIATE" or "EXLUSIVE". See Controlling Transactions "DEFERRED", "IMMEDIATE" or "EXLUSIVE". See ``Controlling Transactions'',
\ref{sqlite3-Controlling-Transactions} for a more detailed explanation. section~\ref{sqlite3-Controlling-Transactions}, for a more detailed explanation.
\end{memberdesc} \end{memberdesc}
\begin{methoddesc}{cursor}{\optional{cursorClass}} \begin{methoddesc}{cursor}{\optional{cursorClass}}
The cursor method accepts a single optional parameter \var{cursorClass}. The cursor method accepts a single optional parameter \var{cursorClass}.
This is a custom cursor class which must extend \class{sqlite3.Cursor}. If supplied, this must be a custom cursor class that extends
\class{sqlite3.Cursor}.
\end{methoddesc} \end{methoddesc}
\begin{methoddesc}{execute}{sql, \optional{parameters}} \begin{methoddesc}{execute}{sql, \optional{parameters}}
...@@ -244,7 +245,7 @@ parameters given. ...@@ -244,7 +245,7 @@ parameters given.
Creates a user-defined function that you can later use from within SQL Creates a user-defined function that you can later use from within SQL
statements under the function name \var{name}. \var{num_params} is the number statements under the function name \var{name}. \var{num_params} is the number
of parameters the function accepts, and \var{func} is a Python callable that is of parameters the function accepts, and \var{func} is a Python callable that is
called as SQL function. called as the SQL function.
The function can return any of the types supported by SQLite: unicode, str, The function can return any of the types supported by SQLite: unicode, str,
int, long, float, buffer and None. int, long, float, buffer and None.
...@@ -274,7 +275,7 @@ Example: ...@@ -274,7 +275,7 @@ Example:
Creates a collation with the specified \var{name} and \var{callable}. The Creates a collation with the specified \var{name} and \var{callable}. The
callable will be passed two string arguments. It should return -1 if the first callable will be passed two string arguments. It should return -1 if the first
is ordered lower than the second, 0 if they are ordered equal and 1 and if the is ordered lower than the second, 0 if they are ordered equal and 1 if the
first is ordered higher than the second. Note that this controls sorting first is ordered higher than the second. Note that this controls sorting
(ORDER BY in SQL) so your comparisons don't affect other SQL operations. (ORDER BY in SQL) so your comparisons don't affect other SQL operations.
...@@ -323,20 +324,21 @@ module. ...@@ -323,20 +324,21 @@ module.
\begin{memberdesc}{row_factory} \begin{memberdesc}{row_factory}
You can change this attribute to a callable that accepts the cursor and You can change this attribute to a callable that accepts the cursor and
the original row as tuple and will return the real result row. This the original row as a tuple and will return the real result row. This
way, you can implement more advanced ways of returning results, like way, you can implement more advanced ways of returning results, such
ones that can also access columns by name. as returning an object that can also access columns by name.
Example: Example:
\verbatiminput{sqlite3/row_factory.py} \verbatiminput{sqlite3/row_factory.py}
If the standard tuple types don't suffice for you, and you want name-based If returning a tuple doesn't suffice and you want name-based
access to columns, you should consider setting \member{row_factory} to the access to columns, you should consider setting \member{row_factory} to the
highly-optimized sqlite3.Row type. It provides both highly-optimized \class{sqlite3.Row} type. \class{Row} provides both
index-based and case-insensitive name-based access to columns with almost index-based and case-insensitive name-based access to columns with almost
no memory overhead. Much better than your own custom dictionary-based no memory overhead. It will probably be better than your own custom
approach or even a db_row based solution. dictionary-based approach or even a db_row based solution.
% XXX what's a db_row-based solution?
\end{memberdesc} \end{memberdesc}
\begin{memberdesc}{text_factory} \begin{memberdesc}{text_factory}
...@@ -350,7 +352,7 @@ module. ...@@ -350,7 +352,7 @@ module.
attribute to \constant{sqlite3.OptimizedUnicode}. attribute to \constant{sqlite3.OptimizedUnicode}.
You can also set it to any other callable that accepts a single bytestring You can also set it to any other callable that accepts a single bytestring
parameter and returns the result object. parameter and returns the resulting object.
See the following example code for illustration: See the following example code for illustration:
...@@ -358,7 +360,7 @@ module. ...@@ -358,7 +360,7 @@ module.
\end{memberdesc} \end{memberdesc}
\begin{memberdesc}{total_changes} \begin{memberdesc}{total_changes}
Returns the total number of database rows that have be modified, inserted, Returns the total number of database rows that have been modified, inserted,
or deleted since the database connection was opened. or deleted since the database connection was opened.
\end{memberdesc} \end{memberdesc}
...@@ -385,9 +387,9 @@ This example shows how to use the named style: ...@@ -385,9 +387,9 @@ This example shows how to use the named style:
\verbatiminput{sqlite3/execute_2.py} \verbatiminput{sqlite3/execute_2.py}
\method{execute} will only execute a single SQL statement. If you try to \method{execute()} will only execute a single SQL statement. If you try to
execute more than one statement with it, it will raise a Warning. Use execute more than one statement with it, it will raise a Warning. Use
\method{executescript} if want to execute multiple SQL statements with one \method{executescript()} if you want to execute multiple SQL statements with one
call. call.
\end{methoddesc} \end{methoddesc}
...@@ -395,7 +397,7 @@ This example shows how to use the named style: ...@@ -395,7 +397,7 @@ This example shows how to use the named style:
\begin{methoddesc}{executemany}{sql, seq_of_parameters} \begin{methoddesc}{executemany}{sql, seq_of_parameters}
Executes a SQL command against all parameter sequences or mappings found in the Executes a SQL command against all parameter sequences or mappings found in the
sequence \var{sql}. The \module{sqlite3} module also allows sequence \var{sql}. The \module{sqlite3} module also allows
to use an iterator yielding parameters instead of a sequence. using an iterator yielding parameters instead of a sequence.
\verbatiminput{sqlite3/executemany_1.py} \verbatiminput{sqlite3/executemany_1.py}
...@@ -407,7 +409,7 @@ Here's a shorter example using a generator: ...@@ -407,7 +409,7 @@ Here's a shorter example using a generator:
\begin{methoddesc}{executescript}{sql_script} \begin{methoddesc}{executescript}{sql_script}
This is a nonstandard convenience method for executing multiple SQL statements This is a nonstandard convenience method for executing multiple SQL statements
at once. It issues a COMMIT statement before, then executes the SQL script it at once. It issues a COMMIT statement first, then executes the SQL script it
gets as a parameter. gets as a parameter.
\var{sql_script} can be a bytestring or a Unicode string. \var{sql_script} can be a bytestring or a Unicode string.
...@@ -464,20 +466,19 @@ This is how SQLite types are converted to Python types by default: ...@@ -464,20 +466,19 @@ This is how SQLite types are converted to Python types by default:
\lineii{BLOB}{buffer} \lineii{BLOB}{buffer}
\end{tableii} \end{tableii}
The type system of the \module{sqlite3} module is extensible in both ways: you can store The type system of the \module{sqlite3} module is extensible in two ways: you can store
additional Python types in a SQLite database via object adaptation, and you can additional Python types in a SQLite database via object adaptation, and you can
let the \module{sqlite3} module convert SQLite types to different Python types via let the \module{sqlite3} module convert SQLite types to different Python types via
converters. converters.
\subsubsection{Using adapters to store additional Python types in SQLite databases} \subsubsection{Using adapters to store additional Python types in SQLite databases}
Like described before, SQLite supports only a limited set of types natively. To As described before, SQLite supports only a limited set of types natively. To
use other Python types with SQLite, you must \strong{adapt} them to one of the sqlite3 use other Python types with SQLite, you must \strong{adapt} them to one of the sqlite3
module's supported types for SQLite. So, one of NoneType, int, long, float, module's supported types for SQLite: one of NoneType, int, long, float,
str, unicode, buffer. str, unicode, buffer.
The \module{sqlite3} module uses the Python object adaptation, like described in PEP 246 The \module{sqlite3} module uses Python object adaptation, as described in \pep{246} for this. The protocol to use is \class{PrepareProtocol}.
for this. The protocol to use is \class{PrepareProtocol}.
There are two ways to enable the \module{sqlite3} module to adapt a custom Python type There are two ways to enable the \module{sqlite3} module to adapt a custom Python type
to one of the supported ones. to one of the supported ones.
...@@ -493,8 +494,8 @@ class Point(object): ...@@ -493,8 +494,8 @@ class Point(object):
self.x, self.y = x, y self.x, self.y = x, y
\end{verbatim} \end{verbatim}
Now you want to store the point in a single SQLite column. You'll have to Now you want to store the point in a single SQLite column. First you'll have to
choose one of the supported types first that you use to represent the point in. choose one of the supported types first to be used for representing the point.
Let's just use str and separate the coordinates using a semicolon. Then you Let's just use str and separate the coordinates using a semicolon. Then you
need to give your class a method \code{__conform__(self, protocol)} which must need to give your class a method \code{__conform__(self, protocol)} which must
return the converted value. The parameter \var{protocol} will be return the converted value. The parameter \var{protocol} will be
...@@ -507,13 +508,13 @@ return the converted value. The parameter \var{protocol} will be ...@@ -507,13 +508,13 @@ return the converted value. The parameter \var{protocol} will be
The other possibility is to create a function that converts the type to the The other possibility is to create a function that converts the type to the
string representation and register the function with \method{register_adapter}. string representation and register the function with \method{register_adapter}.
\verbatiminput{sqlite3/adapter_point_2.py}
\begin{notice} \begin{notice}
The type/class to adapt must be a new-style class, i. e. it must have The type/class to adapt must be a new-style class, i. e. it must have
\class{object} as one of its bases. \class{object} as one of its bases.
\end{notice} \end{notice}
\verbatiminput{sqlite3/adapter_point_2.py}
The \module{sqlite3} module has two default adapters for Python's built-in The \module{sqlite3} module has two default adapters for Python's built-in
\class{datetime.date} and \class{datetime.datetime} types. Now let's suppose \class{datetime.date} and \class{datetime.datetime} types. Now let's suppose
we want to store \class{datetime.datetime} objects not in ISO representation, we want to store \class{datetime.datetime} objects not in ISO representation,
...@@ -523,16 +524,17 @@ but as a \UNIX{} timestamp. ...@@ -523,16 +524,17 @@ but as a \UNIX{} timestamp.
\subsubsection{Converting SQLite values to custom Python types} \subsubsection{Converting SQLite values to custom Python types}
Now that's all nice and dandy that you can send custom Python types to SQLite. Writing an adapter lets you send custom Python types to SQLite.
But to make it really useful we need to make the Python to SQLite to Python But to make it really useful we need to make the Python to SQLite to Python
roundtrip work. roundtrip work.
Enter converters. Enter converters.
Let's go back to the Point class. We stored the x and y coordinates separated Let's go back to the \class{Point} class. We stored the x and y
via semicolons as strings in SQLite. coordinates separated via semicolons as strings in SQLite.
Let's first define a converter function that accepts the string as a parameter and constructs a Point object from it. First, we'll define a converter function that accepts the string as a
parameter and constructs a \class{Point} object from it.
\begin{notice} \begin{notice}
Converter functions \strong{always} get called with a string, no matter Converter functions \strong{always} get called with a string, no matter
...@@ -558,11 +560,12 @@ database is actually a point. There are two ways of doing this: ...@@ -558,11 +560,12 @@ database is actually a point. There are two ways of doing this:
\item Explicitly via the column name \item Explicitly via the column name
\end{itemize} \end{itemize}
Both ways are described at \ref{sqlite3-Module-Contents} in the text explaining Both ways are described in ``Module Constants'', section~\ref{sqlite3-Module-Contents}, in
the constants \constant{PARSE_DECLTYPES} and \constant{PARSE_COlNAMES}. the entries for the constants \constant{PARSE_DECLTYPES} and
\constant{PARSE_COLNAMES}.
The following example illustrates both ways. The following example illustrates both approaches.
\verbatiminput{sqlite3/converter_point.py} \verbatiminput{sqlite3/converter_point.py}
...@@ -571,8 +574,8 @@ The following example illustrates both ways. ...@@ -571,8 +574,8 @@ The following example illustrates both ways.
There are default adapters for the date and datetime types in the datetime There are default adapters for the date and datetime types in the datetime
module. They will be sent as ISO dates/ISO timestamps to SQLite. module. They will be sent as ISO dates/ISO timestamps to SQLite.
The default converters are registered under the name "date" for datetime.date The default converters are registered under the name "date" for \class{datetime.date}
and under the name "timestamp" for datetime.datetime. and under the name "timestamp" for \class{datetime.datetime}.
This way, you can use date/timestamps from Python without any additional This way, you can use date/timestamps from Python without any additional
fiddling in most cases. The format of the adapters is also compatible with the fiddling in most cases. The format of the adapters is also compatible with the
...@@ -584,12 +587,12 @@ The following example demonstrates this. ...@@ -584,12 +587,12 @@ The following example demonstrates this.
\subsection{Controlling Transactions \label{sqlite3-Controlling-Transactions}} \subsection{Controlling Transactions \label{sqlite3-Controlling-Transactions}}
By default, the \module{sqlite3} module opens transactions implicitly before a DML By default, the \module{sqlite3} module opens transactions implicitly before a Data Modification Language (DML)
statement (INSERT/UPDATE/DELETE/REPLACE), and commits transactions implicitly statement (i.e. INSERT/UPDATE/DELETE/REPLACE), and commits transactions implicitly
before a non-DML, non-DQL statement (i. e. anything other than before a non-DML, non-query statement (i. e. anything other than
SELECT/INSERT/UPDATE/DELETE/REPLACE). SELECT/INSERT/UPDATE/DELETE/REPLACE).
So if you are within a transaction, and issue a command like \code{CREATE TABLE So if you are within a transaction and issue a command like \code{CREATE TABLE
...}, \code{VACUUM}, \code{PRAGMA}, the \module{sqlite3} module will commit implicitly ...}, \code{VACUUM}, \code{PRAGMA}, the \module{sqlite3} module will commit implicitly
before executing that command. There are two reasons for doing that. The first before executing that command. There are two reasons for doing that. The first
is that some of these commands don't work within transactions. The other reason is that some of these commands don't work within transactions. The other reason
...@@ -618,17 +621,17 @@ the connection yourself. ...@@ -618,17 +621,17 @@ the connection yourself.
Using the nonstandard \method{execute}, \method{executemany} and Using the nonstandard \method{execute}, \method{executemany} and
\method{executescript} methods of the \class{Connection} object, your code can \method{executescript} methods of the \class{Connection} object, your code can
be written more concisely, because you don't have to create the - often be written more concisely because you don't have to create the (often
superfluous \class{Cursor} objects explicitly. Instead, the \class{Cursor} superfluous) \class{Cursor} objects explicitly. Instead, the \class{Cursor}
objects are created implicitly and these shortcut methods return the cursor objects are created implicitly and these shortcut methods return the cursor
objects. This way, you can for example execute a SELECT statement and iterate objects. This way, you can execute a SELECT statement and iterate
over it directly using only a single call on the \class{Connection} object. over it directly using only a single call on the \class{Connection} object.
\verbatiminput{sqlite3/shortcut_methods.py} \verbatiminput{sqlite3/shortcut_methods.py}
\subsubsection{Accessing columns by name instead of by index} \subsubsection{Accessing columns by name instead of by index}
One cool feature of the \module{sqlite3} module is the builtin \class{sqlite3.Row} class One useful feature of the \module{sqlite3} module is the builtin \class{sqlite3.Row} class
designed to be used as a row factory. designed to be used as a row factory.
Rows wrapped with this class can be accessed both by index (like tuples) and Rows wrapped with this class can be accessed both by index (like tuples) and
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