How to solve TypeError: cannot concatenate 'str' and 'int' objects?

Question

I am trying to retrieve a list in my database. My statement is this:
cr.execute("select es.* from student_resource es where es.date between '"+str(date_from)+"' and '"+str(date_to)+"'")  where *date_from* and* date_to* are of type *fields.date* but when when executed, that is i am trying to access my view, it says:
*TypeError: cannot concatenate 'str' and 'int' objects*
What did i miss with my statement?

Emipro Technologies Pvt. Ltd. · Accepted Answer

Hello,
As your fields are fields.date then you do not need to convert into string. Please write your query as like below.
cr.execute("select es.* from student_resource es where es.date between '" + date_from + "' and '" + date_to + "' ")
*or*
cr.execute("select es.* from student_resource es where es.date between '%s' and '%s' " %(date_from, date_to) )
*Update : or*
query = "select es.* from student_resource es where es.date between '%s' and '%s' " %(date_from, date_to)
cr.execute(query)
When you

Akhil P Sivan · Answer

I think you can use the *to_date() *in psql for that.
Try like this:
cr.execute("select es.* from student_resource es where es.date between to_date(date_from, 'YYYY/MM/DD') and to_date(date_to, 'YYYY/MM/DD')")
*OR*
cr.execute("select es.* from student_resource es where es.date between to_date("+str(date_from)+", 'YYYY/MM/DD') and to_date("+str(date_to)+", 'YYYY/MM/DD') ")

Marvin Taboada · Answer

Quoting Psycopg official references (see here) [1]  :
Psycopg casts Python variables to SQL literals by type. Many standard Python types are already adapted to the correct SQL representation. Don't manually add single quotes depending of the data type, let Psycopg do that for you.
cr.execute(
"""INSERT INTO some_table (an_int, a_date, a_string) VALUES (%s, %s, %s);""",
(11, datetime.date(2007, 07, 27), "Odoo rocks!"))

[1] http://initd.org/psycopg/docs/usage.html

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