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Modify all callers of datatype input and receive functions so that if these

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functions are not strict, they will be called (passing a NULL first parameter)
during any attempt to input a NULL value of their datatype.  Currently, all
our input functions are strict and so this commit does not change any
behavior.  However, this will make it possible to build domain input functions
that centralize checking of domain constraints, thereby closing numerous holes
in our domain support, as per previous discussion.

While at it, I took the opportunity to introduce convenience functions
InputFunctionCall, OutputFunctionCall, etc to use in code that calls I/O
functions.  This eliminates a lot of grotty-looking casts, but the main
motivation is to make it easier to grep for these places if we ever need
to touch them again.
This commit is contained in:
Tom Lane
2006-04-04 19:35:37 +00:00
parent eaef111396
commit 147d4bf3e5
23 changed files with 608 additions and 402 deletions
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19
doc/src/sgml/ref/create_type.sgml
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@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/create_type.sgml,v 1.61 2006/02/28 22:37:25 tgl Exp $
$PostgreSQL: pgsql/doc/src/sgml/ref/create_type.sgml,v 1.62 2006/04/04 19:35:32 tgl Exp $
PostgreSQL documentation
-->
@ -97,8 +97,7 @@ CREATE TYPE <replaceable class="parameter">name</replaceable>
<para>
The <replaceable class="parameter">input_function</replaceable>
converts the type's external textual representation to the internal
representation used by the
operators and functions defined for the type.
representation used by the operators and functions defined for the type.
<replaceable class="parameter">output_function</replaceable>
performs the reverse transformation. The input function may be
declared as taking one argument of type <type>cstring</type>,
@ -110,9 +109,16 @@ CREATE TYPE <replaceable class="parameter">name</replaceable>
and the third is the <literal>typmod</> of the destination column, if known
(-1 will be passed if not).
The input function must return a value of the data type itself.
Usually, an input function should be declared STRICT; if it is not,
it will be called with a NULL first parameter when reading a NULL
input value. The function must still return NULL in this case, unless
it raises an error.
(This case is mainly meant to support domain input functions, which
may need to reject NULL inputs.)
The output function must be
declared as taking one argument of the new data type.
The output function must return type <type>cstring</type>.
Output functions are not invoked for NULL values.
</para>
<para>
@ -133,6 +139,12 @@ CREATE TYPE <replaceable class="parameter">name</replaceable>
holding the received byte string; the optional arguments are the
same as for the text input function.
The receive function must return a value of the data type itself.
Usually, a receive function should be declared STRICT; if it is not,
it will be called with a NULL first parameter when reading a NULL
input value. The function must still return NULL in this case, unless
it raises an error.
(This case is mainly meant to support domain receive functions, which
may need to reject NULL inputs.)
Similarly, the optional
<replaceable class="parameter">send_function</replaceable> converts
from the internal representation to the external binary representation.
@ -140,6 +152,7 @@ CREATE TYPE <replaceable class="parameter">name</replaceable>
output. The send function must be
declared as taking one argument of the new data type.
The send function must return type <type>bytea</type>.
Send functions are not invoked for NULL values.
</para>
<para>