#28643: Complete the ORM Function Library
-------------------------------------+-------------------------------------
Reporter: Matthew Pava | Owner: JunyiJ
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
-------------------------------------+-------------------------------------
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. There are probably several more that I
> have missed. These functions are available directly out of the box with
> PostgreSQL.
>
> String functions not yet implemented:
> ASCII(): Returns numeric value of left-most character
> CHR(): Character with the given code.
> LEFT(): Returns the leftmost number of characters as specified
> LPAD(): Returns the string argument, left-padded with the specified
> string
> MD5(): Calculates the MD5 hash of string, returning the result in
> hexadecimal
> REPEAT(): Repeats a string the specified number of times
> REPLACE(): Replaces occurrences of a specified string
> REVERSE(): Reverse the characters in a string
> RIGHT(): Returns the specified rightmost number of characters
> RPAD(): Appends string the specified number of times
> LTRIM(): Removes leading spaces
> ([https://github.com/django/django/pull/9220 PR #9220])
> RTRIM(): Removes trailing spaces
> ([https://github.com/django/django/pull/9220 PR #9220])
> TRIM(): Removes leading and trailing spaces
> ([https://github.com/django/django/pull/9220 PR #9220])
>
> Numeric functions:
> ABS(): Returns the absolute value.
> ACOS(): Returns the arccosine.
> ASIN(): Returns the arcsine.
> ATAN(): Returns the arctangent.
> ATAN2(): Returns the arctangent of the two variables passed to it.
> CEILING(): Returns the smallest integer value that is not less than a
> numeric expression
> COS(): Returns the cosine expressed in radians.
> COT(): Returns the cotangent.
> DEGREES(): Returns a numeric expression converted from radians to
> degrees.
> EXP(): Returns the base of the natural logarithm (e) raised to the power
> of a numeric expression.
> FLOOR(): Returns the largest integer value that is not greater than a
> numeric expression.
> LOG(): Returns the natural logarithm of a numeric expression.
> MOD(): Returns the remainder of one expression by diving by another
> expression.
> PI(): Returns the value of pi
> POWER(): Returns the value of one expression raised to the power of
> another expression
> RADIANS(): Returns the value of an expression converted from degrees to
> radians.
> ROUND(): Returns a numeric expression rounded to an integer. Can be used
> to round an expression to a number of decimal points
> SIN(): Returns the sine given in radians.
> SQRT(): Returns the square root.
> TAN(): Returns the tangent expressed in radians.
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.
||= String =||
||Name||Description||PostgreSQL||Oracle||MySQL||SQLite||PR||
||ASCII()||Returns numeric value of left-most character||X||X||X||as
UNICODE()||-||
||CHR()||Character with the given code||X||X||as CHAR()||as CHAR()||-||
||LEFT()||Returns the leftmost number of characters as
specified||X||-||X||-||-||
||LPAD()||Returns the string argument, left-padded with the specified
string||X||X||X||-||-||
||MD5()||Calculates the MD5 hash of string, returning the result in
hexadecimal||X||-||-||-||-||
||REPEAT()||Repeats a string the specified number of
times||X||-||X||-||-||
||REPLACE()||Replaces occurrences of a specified string||X||X||X||X||-||
||REVERSE()||Reverse the characters in a string||X||-||X||-||-||
||RIGHT()||Returns the specified rightmost number of
characters||X||-||X||-||-||
||RPAD()||Appends string the specified number of times||X||X||X||-||-||
||LTRIM()||Removes leading
spaces||X||X||X||X||[https://github.com/django/django/pull/9220 9220]||
||RTRIM()||Removes trailing
spaces||X||X||X||X||[https://github.com/django/django/pull/9220 9220]||
||TRIM()||Removes leading and trailing
spaces||X||X||X||X||[https://github.com/django/django/pull/9220 9220]||
||= Numeric =||
||Name||Description||PostgreSQL||Oracle||MySQL||SQLite||PR||
||ABS()||Returns the absolute value.||X||X||X||X||-||
||ACOS()||Returns the arccosine.||X||X||X||-||-||
||ASIN()||Returns the arcsine.||X||X||X||-||-||
||ATAN()||Returns the arctangent.||X||X||X||-||-||
||ATAN2()||Returns the arctangent of the two variables passed to
it.||X||X||X||-||-||
||CEILING()||Returns the smallest integer value that is not less than a
numeric expression||X||as CEIL()||X||-||-||
||COS()||Returns the cosine expressed in radians.||X||X||X||-||-||
||COT()||Returns the cotangent.||X||X||X||-||-||
||DEGREES()||Returns a numeric expression converted from radians to
degrees.||X||X||X||-||-||
||EXP()||Returns the base of the natural logarithm (e) raised to the power
of a numeric expression.||X||X||X||-||-||
||FLOOR()||Returns the largest integer value that is not greater than a
numeric expression.||X||X||X||-||-||
||LOG()||Returns the natural logarithm of a numeric
expression.||X||X||X||-||-||
||MOD()||Returns the remainder of one expression by diving by another
expression.||X||X||X||-||-||
||PI()||Returns the value of pi||X||-||X||-||-||
||POWER()||Returns the value of one expression raised to the power of
another expression||X||X||X||-||-||
||RADIANS()||Returns the value of an expression converted from degrees to
radians.||X||X||X||-||-||
||ROUND()||Returns a numeric expression rounded to an integer. Can be used
to round an expression to a number of decimal points||X||X||X||X||-||
||SIN()||Returns the sine given in radians.||X||X||X||-||-||
||SQRT()||Returns the square root.||X||X||X||-||-||
||TAN()||Returns the tangent expressed in radians.||X||X||X||-||-||
--
Comment (by Matthew Pava):
I formatted the list into a table so we could see better what we can do to
address this ticket. It looks like SQLite is missing much functionality
that the other backends support, especially in the math department.
I also suggest implementing Left and Right, but for the unsupported
backends to use the corresponding Substr function.
--
Ticket URL: <https://code.djangoproject.com/ticket/28643#comment:22>
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