#28643: Complete the ORM Function Library
-------------------------------------+-------------------------------------
Reporter: Matthew Pava | Owner: Nick Pope
Type: New feature | Status: assigned
Component: Database layer | Version: master
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Description changed by Tim Graham:
Old description:
> I was surprised to learn that we didn't have a StrIndex function until
> version 2, and yet we had Substr since at least version 1.8. I wonder
> how users were using Substr without also finding a use for StrIndex this
> whole time. Anyway, since we seem to be adding these functions one at a
> time, why don't we work on trying to get the built-ins implemented in one
> sweep instead?
>
> We may even want to split the documentation page
> (https://docs.djangoproject.com/en/dev/ref/models/database-functions/)
> into further categories with String functions and Numeric functions.
>
> This is just a sample checklist, with corresponding attributes to which
> backend has them available.
>
> ||||||||||||||||= **Comparison** =||
> ||**Django**||**SQL**||**Description**||**PostgreSQL**||**Oracle**||**MySQL**||**SQLite**||**PR**||
> ||{{{NullIf}}}||{{{NULLIF}}}||Returns {{{NULL}}} if the first argument
> equals the
> second.||✔||✔||✔||✔||[https://github.com/django/django/pull/9543
> 9543]||
> ||||||||||||||||= **Math** =||
> ||**Django**||**SQL**||**Description**||**PostgreSQL**||**Oracle**||**MySQL**||**SQLite**||**PR**||
> ||{{{Abs}}}||{{{ABS}}}||Returns the absolute
> value.||✔||✔||✔||✔||~~9622~~||
> ||{{{ACos}}}||{{{ACOS}}}||Returns the
> arccosine.||✔||✔||✔||✔**^1^**||~~9622~~||
> ||{{{ASin}}}||{{{ASIN}}}||Returns the
> arcsine.||✔||✔||✔||✔**^1^**||~~9622~~||
> ||{{{ATan}}}||{{{ATAN}}}||Returns the
> arctangent.||✔||✔||✔||✔**^1^**||~~9622~~||
> ||{{{ATan2}}}||{{{ATAN2}}}||Returns the arctangent of the two variables
> passed to it.||✔||✔||✔||✔**^1^**||~~9622~~||
> ||{{{Ceil}}}||{{{CEILING}}}||Returns the smallest integer value that is
> not less than a numeric
> expression||✔||{{{CEIL}}}||✔||✔**^1^**||~~9622~~||
> ||{{{Cos}}}||{{{COS}}}||Returns the cosine expressed in
> radians.||✔||✔||✔||✔**^1^**||~~9622~~||
> ||{{{Cot}}}||{{{COT}}}||Returns the
> cotangent.||✔||✔**^5^**||✔||✔**^1^**||~~9622~~||
> ||{{{Degrees}}}||{{{DEGREES}}}||Returns a numeric expression converted
> from radians to degrees.||✔||✔||✔||✔**^1^**||~~9622~~||
> ||{{{Exp}}}||{{{EXP}}}||Returns the base of the natural logarithm (e)
> raised to the power of a numeric
> expression.||✔||✔||✔||✔**^1^**||~~9622~~||
> ||{{{Floor}}}||{{{FLOOR}}}||Returns the largest integer value that is not
> greater than a numeric expression.||✔||✔||✔||✔**^1^**||~~9622~~||
> ||{{{Ln}}}||{{{LN}}}||Returns the natural logarithm of a numeric
> expression.||✔||✔||✔||✔**^1^**||~~9622~~||
> ||{{{Log}}}||{{{LOG(B, X)}}}||Returns the logarithm of a numeric
> expression.||✔||✔||✔||✔**^1^**||~~9622~~||
> ||{{{Mod}}}||{{{MOD}}}||Returns the remainder of one expression by diving
> by another expression.||✔||✔||✔||✔**^1^**||~~9622~~||
> ||{{{Pi}}}||{{{PI}}}||Returns the value of
> π||✔||✔**^4^**||✔||✔**^1^**||~~9622~~||
> ||{{{Power}}}||{{{POWER}}}||Returns the value of one expression raised to
> the power of another expression||✔||✔||✔||✔**^1^**||~~9622~~||
> ||{{{Radians}}}||{{{RADIANS}}}||Returns the value of an expression
> converted from degrees to radians.||✔||✔||✔||✔**^1^**||~~9622~~||
> ||{{{Round}}}||{{{ROUND}}}||Returns a numeric expression rounded to an
> integer.\\Can be used to round an expression to a number of decimal
> points||✔||✔||✔||✔||~~9622~~||
> ||{{{Sin}}}||{{{SIN}}}||Returns the sine given in
> radians.||✔||✔||✔||✔**^1^**||~~9622~~||
> ||{{{Sqrt}}}||{{{SQRT}}}||Returns the square
> root.||✔||✔||✔||✔**^1^**||~~9622~~||
> ||{{{Tan}}}||{{{TAN}}}||Returns the tangent expressed in
> radians.||✔||✔||✔||✔**^1^**||~~9622~~||
> ||||||||||||||||= **Text** =||
> ||**Django**||**SQL**||**Description**||**PostgreSQL**||**Oracle**||**MySQL**||**SQLite**||**PR**||
> ||{{{Ord}}}||{{{ASCII}}}||Returns numeric value of left-most character.
> (Equivalent to {{{ord()}}} in
> Python.)||✔||✔||✔||{{{UNICODE}}}||~~9583~~||
> ||{{{Chr}}}||{{{CHR}}}||Character with the given
> code||✔||✔||{{{CHAR}}}||{{{CHAR}}}||~~9583~~||
> ||{{{Left}}}||{{{LEFT}}}||Returns the leftmost number of characters as
> specified||✔||✔**^2, 6^**||✔||✔**^2^**||~~9583~~||
> ||{{{LPad}}}||{{{LPAD}}}||Returns the string argument, left-padded with
> the specified string||✔||✔||✔||✔**^1^**||~~9798~~||
> ||{{{LTrim}}}||{{{LTRIM}}}||Removes leading
> spaces||✔||✔||✔||✔||~~9220~~||
> ||{{{MD5}}}||{{{MD5}}}||Calculates the MD5 hash of string, returning the
> result in hexadecimal||✔||-||-||✔**^1^**||-||
> ||{{{Repeat}}}||{{{REPEAT}}}||Repeats a string the specified number of
> times||✔||✔**^3^**||✔||✔**^1^**||~~9808~~||
> ||{{{Replace}}}||{{{REPLACE}}}||Replaces occurrences of a specified
> string||✔||✔**^6^**||✔||✔||~~9539~~||
> ||{{{Reverse}}}||{{{REVERSE}}}||Reverse the characters in a
> string||✔||✔**^6,
> 7^**||✔||✔**^1^**||[https://github.com/django/django/pull/10827 10827]||
> ||{{{Right}}}||{{{RIGHT}}}||Returns the specified rightmost number of
> characters||✔||✔**^2^**||✔||✔**^2^**||~~9583~~||
> ||{{{RPad}}}||{{{RPAD}}}||Appends string the specified number of
> times||✔||✔**^6^**||✔||✔**^1^**||~~9798~~||
> ||{{{RTrim}}}||{{{RTRIM}}}||Removes trailing
> spaces||✔||✔||✔||✔||~~9220~~||
> ||{{{Trim}}}||{{{TRIM}}}||Removes leading and trailing
> spaces||✔||✔||✔||✔||~~9220~~||
>
> - **^1^** Function can be easily supported on SQLite with a
> [https://docs.python.org/3/library/sqlite3.html#sqlite3.Connection.create_function
> user defined function].
> - **^2^** Behaviour can be emulated by using {{{SUBSTR}}}.
> - **^3^** Behaviour can be emulated by using {{{LENGTH}}} and {{{RPAD}}}.
> - **^4^** Behaviour can be emulated by directly substituting constant
> {{{math.pi}}}.
> - **^5^** Behaviour can be emulated by using {{{1 / TAN(X)}}}.
> - **^6^** Doesn't work properly with multibyte characters sets on Oracle.
> - **^7^** The {{{REVERSE}}} function is undocumented on Oracle.
New description:
I was surprised to learn that we didn't have a StrIndex function until
version 2, and yet we had Substr since at least version 1.8. I wonder how
users were using Substr without also finding a use for StrIndex this whole
time. Anyway, since we seem to be adding these functions one at a time,
why don't we work on trying to get the built-ins implemented in one sweep
instead?
We may even want to split the documentation page
(https://docs.djangoproject.com/en/dev/ref/models/database-functions/)
into further categories with String functions and Numeric functions.
This is just a sample checklist, with corresponding attributes to which
backend has them available.
||||||||||||||||= **Comparison** =||
||**Django**||**SQL**||**Description**||**PostgreSQL**||**Oracle**||**MySQL**||**SQLite**||**PR**||
||`NullIf`||`NULLIF`||Returns `NULL` if the first argument equals the
second.||✔||✔||✔||✔||~~9543~~||
||||||||||||||||= **Math** =||
||**Django**||**SQL**||**Description**||**PostgreSQL**||**Oracle**||**MySQL**||**SQLite**||**PR**||
||`Abs`||`ABS`||Returns the absolute value.||✔||✔||✔||✔||~~9622~~||
||`ACos`||`ACOS`||Returns the arccosine.||✔||✔||✔||✔**^1^**||~~9622~~||
||`ASin`||`ASIN`||Returns the arcsine.||✔||✔||✔||✔**^1^**||~~9622~~||
||`ATan`||`ATAN`||Returns the
arctangent.||✔||✔||✔||✔**^1^**||~~9622~~||
||`ATan2`||`ATAN2`||Returns the arctangent of the two variables passed to
it.||✔||✔||✔||✔**^1^**||~~9622~~||
||`Ceil`||`CEILING`||Returns the smallest integer value that is not less
than a numeric expression||✔||`CEIL`||✔||✔**^1^**||~~9622~~||
||`Cos`||`COS`||Returns the cosine expressed in
radians.||✔||✔||✔||✔**^1^**||~~9622~~||
||`Cot`||`COT`||Returns the
cotangent.||✔||✔**^5^**||✔||✔**^1^**||~~9622~~||
||`Degrees`||`DEGREES`||Returns a numeric expression converted from
radians to degrees.||✔||✔||✔||✔**^1^**||~~9622~~||
||`Exp`||`EXP`||Returns the base of the natural logarithm (e) raised to
the power of a numeric expression.||✔||✔||✔||✔**^1^**||~~9622~~||
||`Floor`||`FLOOR`||Returns the largest integer value that is not greater
than a numeric expression.||✔||✔||✔||✔**^1^**||~~9622~~||
||`Ln`||`LN`||Returns the natural logarithm of a numeric
expression.||✔||✔||✔||✔**^1^**||~~9622~~||
||`Log`||`LOG(B, X)`||Returns the logarithm of a numeric
expression.||✔||✔||✔||✔**^1^**||~~9622~~||
||`Mod`||`MOD`||Returns the remainder of one expression by diving by
another expression.||✔||✔||✔||✔**^1^**||~~9622~~||
||`Pi`||`PI`||Returns the value of
π||✔||✔**^4^**||✔||✔**^1^**||~~9622~~||
||`Power`||`POWER`||Returns the value of one expression raised to the
power of another expression||✔||✔||✔||✔**^1^**||~~9622~~||
||`Radians`||`RADIANS`||Returns the value of an expression converted from
degrees to radians.||✔||✔||✔||✔**^1^**||~~9622~~||
||`Round`||`ROUND`||Returns a numeric expression rounded to an
integer.\\Can be used to round an expression to a number of decimal
points||✔||✔||✔||✔||~~9622~~||
||`Sin`||`SIN`||Returns the sine given in
radians.||✔||✔||✔||✔**^1^**||~~9622~~||
||`Sqrt`||`SQRT`||Returns the square
root.||✔||✔||✔||✔**^1^**||~~9622~~||
||`Tan`||`TAN`||Returns the tangent expressed in
radians.||✔||✔||✔||✔**^1^**||~~9622~~||
||||||||||||||||= **Text** =||
||**Django**||**SQL**||**Description**||**PostgreSQL**||**Oracle**||**MySQL**||**SQLite**||**PR**||
||`Ord`||`ASCII`||Returns numeric value of left-most character.
(Equivalent to `ord()` in Python.)||✔||✔||✔||`UNICODE`||~~9583~~||
||`Chr`||`CHR`||Character with the given
code||✔||✔||`CHAR`||`CHAR`||~~9583~~||
||`Left`||`LEFT`||Returns the leftmost number of characters as
specified||✔||✔**^2, 6^**||✔||✔**^2^**||~~9583~~||
||`LPad`||`LPAD`||Returns the string argument, left-padded with the
specified string||✔||✔||✔||✔**^1^**||~~9798~~||
||`LTrim`||`LTRIM`||Removes leading spaces||✔||✔||✔||✔||~~9220~~||
||`MD5`||`MD5`||Calculates the MD5 hash of string, returning the result in
hexadecimal||✔||-||-||✔**^1^**||-||
||`Repeat`||`REPEAT`||Repeats a string the specified number of
times||✔||✔**^3^**||✔||✔**^1^**||~~9808~~||
||`Replace`||`REPLACE`||Replaces occurrences of a specified
string||✔||✔**^6^**||✔||✔||~~9539~~||
||`Reverse`||`REVERSE`||Reverse the characters in a string||✔||✔**^6,
7^**||✔||✔**^1^**||~~10827~~||
||`Right`||`RIGHT`||Returns the specified rightmost number of
characters||✔||✔**^2^**||✔||✔**^2^**||~~9583~~||
||`RPad`||`RPAD`||Appends string the specified number of
times||✔||✔**^6^**||✔||✔**^1^**||~~9798~~||
||`RTrim`||`RTRIM`||Removes trailing spaces||✔||✔||✔||✔||~~9220~~||
||`Trim`||`TRIM`||Removes leading and trailing
spaces||✔||✔||✔||✔||~~9220~~||
- **^1^** Function can be easily supported on SQLite with a
[https://docs.python.org/3/library/sqlite3.html#sqlite3.Connection.create_function
user defined function].
- **^2^** Can be emulated by using `SUBSTR`.
- **^3^** Can be emulated by using `LENGTH` and `RPAD`.
- **^4^** Can be emulated by directly substituting constant `math.pi`.
- **^5^** Can be emulated by using `1 / TAN(X)`.
- **^6^** Doesn't work properly with multibyte characters sets on Oracle.
- **^7^** The `REVERSE` function is undocumented on Oracle.
--
--
Ticket URL: <https://code.djangoproject.com/ticket/28643#comment:50>
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