Oh, Michael!
You have made my day. It just gets better and better!
I don't know how I missed these items, but your examples are very helpful.
Many thanks!
On Tuesday, September 8, 2015 at 7:00:12 PM UTC-6, Michael Bayer wrote:
>
>
>
> On 9/8/15 12:57 PM, Steve Murphy wrote:
>
>
> A bit difficult is grabbing just certain columns in the select, given
> that we have only a list of column names. That would be real nice
> if such a method were available in the core API.
>
> For example, a method for select whereby I could supply a simple
> list of column names to fetch in the select would be very handy:
>
> tablename = "user"
> tab = meta1.tables[tablename]
> collist = [ "id", "name", "address" ] ## just a few of many more
> q = tab.select(colnames=collist)
>
> this is pretty simple:
>
> q = select([tab.c[name] for name in ["id", "name", "address"]])
>
> Also, if I could get a column object from a table by name
> it would really make life easier at times:
>
> q = select([tab]).where(tab.colname(colnamevar) == col_var_val)
>
>
> yeah, tab.c[name]
>
> this is here:
>
>
> http://docs.sqlalchemy.org/en/rel_1_0/core/metadata.html#accessing-tables-and-columns
>
>
>
> Another rough spot with the API is setting up a simple set of where
> clauses for a select, given a map of column names vs. values.
> if the map contained {"user": "cat", "city": "Gotham"} it would
> be cool if we could get the desired select:
>
> select * from table where user='cat' and city='Gotham';
>
>
> that is:
>
> select = select.where(and_(*[tab.c[key] == value for key, value in
> mymap.items()]))
>
>
> Another rough spot is getting a list of constraints. I note that
> postgresql has sql to create constraints, and remove them, but
> not to get a list of them.
>
> you can get these like this:
>
> from sqlalchemy import inspect
> insp = inspect(my_engine)
>
> fk_constraints = insp.get_foreign_keys('mytable')
> uq_constraints = insp.get_unique_constraints('mytable')
> indexes = insp.get_indexes('mytable')
>
> docs:
> http://docs.sqlalchemy.org/en/rel_1_0/core/reflection.html#fine-grained-reflection-with-inspector
>
> there's no listing of CHECK constraints right now.
>
> they are also available on the Table as fully constructed constraint
> objects:
>
> table = Table('mytable', somemetadata, autoload=True)
> for constraint in table.constraints:
> # ...
>
>
> docs for the table.constraints accessor are not in good shape right now,
> the API docs aren't generating for it and there's only a few mentions of
> it, but inspector is usually more straightforward if you are just getting
> raw information about them.
>
>
>
> I do see the "\d " command,
> and you get a list of all the foreign keys and constraints that way,
> all in a big block of text I'm sure that, without supporting sql
> syntax,
> any further sqlalchemy constraint support will be very hard, if not
> impossible,
> to implement.
>
> well \d is just part of your psql shell, it is ultimately querying the
> pg_catalog tables which is what the SQLA postgresql dialect queries as well.
>
>
>
> The fact that sqlalchemy does what it does has saved me a ton of time
> writing
> a full-blown SQL parser. Many congrats, thanks, ataboys, and kudu's!!!
>
>
> thanks glad its working out!
>
>
>
> murf
>
>
>
> --
> You received this message because you are subscribed to the Google Groups
> "sqlalchemy" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to sqlalchemy+...@googlegroups.com .
> To post to this group, send email to sqlal...@googlegroups.com
> .
> Visit this group at http://groups.google.com/group/sqlalchemy.
> For more options, visit https://groups.google.com/d/optout.
>
>
>
--
You received this message because you are subscribed to the Google Groups
"sqlalchemy" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to sqlalchemy+unsubscr...@googlegroups.com.
To post to this group, send email to sqlalchemy@googlegroups.com.
Visit this group at http://groups.google.com/group/sqlalchemy.
For more options, visit https://groups.google.com/d/optout.
