Obtaining the db information from a table expression

[mikeonghub]

Hello 👋

This library is really great, thanks for all your hard work!

Hopefully this isn't a silly question, I have a script where I am extracting the tables from a query, when I print an individual table I get the perfect output of dbname.tablename however when I add the individual table to a dictionary I get {(TABLE this: (IDENTIFIER this: tablename, quoted: True), db: (IDENTIFIER this: dbname, quoted: False))

I would ideally love to store the clean dbname.tablename in the dictionary, but I can't seem to figure out how the library is generating that format on the print.

Thanks again for the awesome library and for taking a look at my question.

[barakalon]

First, I think there is some confusion about fundamental Python behavior.

From the python docs for print:

All non-keyword arguments are converted to strings like str() does and written to the stream

So when you do print(obj), str(obj) gets called.

However, when converting a dict object to a str, Python will call repr on it's entries.

So when you do print({"a": obj}), repr(obj) gets called.

So a good way to dig into this behavior is to check the __str__ and __repr__ methods of the object.

For sqlglot, __repr__ calls the to_s method, and __str__ calls the sql method:

import sqlglot
from sqlglot import expressions as exp

table = sqlglot.parse_one("SELECT a FROM db.x").find(exp.Table)

print(table.to_s())
#  (TABLE this:
#    (IDENTIFIER this: x, quoted: False), db:
#    (IDENTIFIER this: db, quoted: False))

print(repr(table))
#  (TABLE this:
#    (IDENTIFIER this: x, quoted: False), db:
#    (IDENTIFIER this: db, quoted: False))

print(table.sql())
#  db.x

print(str(table))
#  db.x

Now, keep in mind that the string that repr returns is NOT what's getting stored in your dictionary - the sqlglot Table object is. You're just seeing the result of calling str on the dictionary.

---

tldr:

{"a": table.sql()}

[mikeonghub]

Wow @barakalon I'm embarrased, I dug around __str__ and __repr__ but forgot to put together the basic what print and what print(dict) were doing. Thank you so much for your answer!

[barakalon]

yep 😄