Scala noob i'm afraid:
I have the following declared class variable which will the objects I read from the database:
val options = mutable.LinkedList[DivisionSelectOption]()
I then use JPA to get a List of all rows from a table:
val divisionOptions = em.createNamedQuery("SelectOption.all", classOf[SelectOption]) getResultList
/* Wrap java List in Scala List */
val wrappedOptions = JListWrapper.apply(divisionOptions)
/* Store the wrappedOptions in the class variable */
options += wrappedOptions
However, the last line has an error:
Type Expected: String, actual JListWrapper[SelectOption]
Can anyone help with what I am doing wrong? I'm just trying to populate the options object with the result of the DB call.
Thanks
What (probably) is happening is that a JlistWrapper[SelectOption] isn't a DivisionSelectOption, so the method += isn't applicable to it. That being the case, it is trying other stuff, and giving a final error on this:
options = options + wrappedOptions
That is a rewriting Scala can do to make things like x += 1 work for var x. The + method is present on all objects, but it takes a String as parameter -- that's so one can write stuff like options + ":" and have that work as in Java. But since wrappedOptions isn't a String, it complains.
Roundabout and confusing, I know, and even Odersky regrets his decision with regards to +. Let that be a lesson: if you thing of adding a method to Any, think really hard before doing it.
Related
I am trying to just do a basic INSERT operation to a PostgreSQL database through Python via the Psycopg2 module. I have read a great many of the questions already posted regarding this subject as well as the documentation but I seem to have done something uniquely wrong and none of the fixes seem to work for my code.
#API CALL + JSON decoding here
x = 0
for item in ulist:
idValue = list['members'][x]['name']
activeUsers.append(str(idValue))
x += 1
dbShell.executemany("""INSERT INTO slickusers (username) VALUES (%s)""", activeUsers
)
The loop creates a list of strings that looks like this when printed:
['b2ong', 'dune', 'drble', 'drars', 'feman', 'got', 'urbo']
I am just trying to have the code INSERT these strings as 1 row each into the table.
The error specified when running is:
TypeError: not all arguments converted during string formatting
I tried changing the INSERT to:
dbShell.executemany("INSERT INTO slackusers (username) VALUES (%s)", (activeUsers,) )
But that seems like it's merely treating the entire list as a single string as it yields:
psycopg2.DataError: value too long for type character varying(30)
What am I missing?
First in the code you pasted:
x = 0
for item in ulist:
idValue = list['members'][x]['name']
activeUsers.append(str(idValue))
x += 1
Is not the right way to accomplish what you are trying to do.
first list is a reserved word in python and you shouldn't use it as a variable name. I am assuming you meant ulist.
if you really need access to the index of an item in python you can use enumerate:
for x, item in enumerate(ulist):
but, the best way to do what you are trying to do is something like
for item in ulist: # or list['members'] Your example is kinda broken here
activeUsers.append(str(item['name']))
Your first try was:
['b2ong', 'dune', 'drble', 'drars', 'feman', 'got', 'urbo']
Your second attempt was:
(['b2ong', 'dune', 'drble', 'drars', 'feman', 'got', 'urbo'], )
What I think you want is:
[['b2ong'], ['dune'], ['drble'], ['drars'], ['feman'], ['got'], ['urbo']]
You could get this many ways:
dbShell.executemany("INSERT INTO slackusers (username) VALUES (%s)", [ [a] for a in activeUsers] )
or event better:
for item in ulist: # or list['members'] Your example is kinda broken here
activeUsers.append([str(item['name'])])
dbShell.executemany("""INSERT INTO slickusers (username) VALUES (%s)""", activeUsers)
I want to create a function that works on a single date or over a period of time. For that I make a list of strings like this:
import com.github.nscala_time.time.Imports._
val fromDate = "2015-10-15".toLocalDate
val toDate = "2015-10-15".toLocalDate
val days = Iterator.iterate(fromDate)(_ + 1.day).takeWhile(_ <= toDate).map(_.toString)
Now I want to access days content:
scala> days.foreach(println)
2015-10-15
scala> days.foreach(day => println(day))
With the first foreach I get the only element in days list, but with the second I get nothing. This is just a sample, but I need to use the 2nd form, because I need to use day value inside the function.
If I use a range both methods work like they are supposed to...
Anyone knows why this behaviour?
Thanks in advance!
P.D. I don't want to use another method to create the list of strings (unless I can't find a solution for this)
Second function works in same way as first.
You've created Iterator object, which you can iterate only once.
To be able use it any amount of times just convert you iterator to list.
val daysL = days.toList
How do I write a simple ABAP Unit Assert statement to check if any call, expression or other statement evaluates to true?
I can't see any basic assert() or assert_true() methods in CL_AUNIT_ASSERT while I'd expect those to be very common. I can approximate such an assert as follows, but is there no cleaner way?
cl_aunit_assert=>assert_equals(
act = boolc( lv_value > 100 OR lv_value < 2 )
exp = abap_true ).
cl_aunit_assert=>assert_equals(
act = mo_model->is_active )
exp = abap_true ).
Depending on your SAP NetWeaver stack you can (or should) use the updated ABAP Unit Class CL_ABAP_UNIT_ASSERT. This class is available at a Basis-Release >= 7.02. SAP declared this class as 'FINAL' so it´s impossible to inherit from it, but on the other side they added some ASSERT-Methods like the ASSERT_TRUE Method!
Here is a possible usage of this method:
cl_abap_unit_assert=>assert_true(
exporting
act = m_ref_foo->is_bar( l_some_var )
msg = 'is_bar Method fails with Input { l_some_var }'
).
For the releases I have access to, there's probably no shorter way than the one you outlined. You can create a subclass of CL_AUNIT_ASSERT and add your own static ASSERT_TRUE method. It's not a bad idea to do so and at the same time make your local ABAP Unit test class a subclass of that ZCL_AUNIT_ASSERT - this way, you can omit the cl_aunit_assert=> prefix which will save some keystrokes.
You cannot see such methods because there is no boolean type in ABAP.
While in Java, C++ or C, you are able to assign a result of a condition to a variable, like this
int i = 5;
boolean result = i > 3;
You cannot do the same thing in ABAP as there is no boolean type. Therefore what in other languages is a one liner, in ABAP it will always be more prolix.
DATA: i TYPE i VALUE 5.
DATA: result TYPE abap_bool.
IF i > 3.
result = abap_true.
ELSE.
result = abap_false.
ENDIF.
The thing you used seems to be a new feature, that has been recently added to the language and most of the customers will not be using for a long time. Also the CL_AUNIT_ASSERT class was created way before the new elements came to the language.
So right now, there is a possibility to write the above thing as one liner. However there is still no boolean type in the language.
DATA: i TYPE i VALUE 5.
DATA: result TYPE abap_bool.
result = boolc( i > 3 ).
On the other hand, there is no boolean type, but you could simply use ASSERT_INITIAL or ASSERT_NOT_INITIAL in this case, as boolean is emulated by either X (true) or space (false). The latter is an initial value in ABAP.
The cleanest way is to just fail:
if value > limit.
cl_abap_unit_assert=>fail( ).
endif.
Or a more informative:
cl_abap_unit=>fail( msg = 'Limit exceeded' ).
This is the error I'm getting and I have no idea why: "Error: Unbound record field label length "
Does anyonw know?
let rastavi str =
let sublist = ref [] in
let list = ref [] in
for i = ((str.length str)1) [down]to 0 do
if str.[i] =' ' then (str.[i] :: !sublist)
else (list := (!sublist:: !list)) sublist = []
done ;;
You're using OO notation to get the length of a string. OCaml uses functional notation. So it looks like this:
String.length str
Not like this:
str.length (* OO notation, not in OCaml *)
Edit:
Side comment: this solution is very much an imperative take on the problem. If you're trying to learn the FP mindset, you should try to think recursively and immutably. Since this looks like homework, it's very likely a functional solution is what you want.
But here are a few other problems in your original code:
You have two expressions next to each other with nothing in between. If you want to "do" two things, you need to separate them with a semicolon ; (however, this is imperative style)
You're using = which compares two values for equality. If you want to assign a value to a reference you need to use :=. (Imperative style, again.)
I have what I believe to be an embarrassingly simple problem, but three hours of googling and checking stackoverflow have not helped.
Let's say I have a very simple piece of code:
def secret_formula(started):
jelly_beans = started*500
jars = jelly_beans/1000
crates = jars/100
return jelly_beans,jars,crates
start_point = 10000
print("We'd have {} beans, {} jars, and {} crates.".format(secret_formula(start_point)))
What happens is I get the "IndexError: tuple index out of range". So I just print the secret_formula function to see what it looks like, and it looks like this:
(5000000, 5000.0, 50.0)
Basically, it is treating the output as one 'thing' (I am still very new, sorry if my language is not correct). My question is, why does it treat it like this and how do I make it pass the three outputs (jelly_beans, jars, and crates) so that it formats the string properly?
Thanks!
The format function of the string take a variable number of argument. The secret_formula function is returning a tuple. You want to convert that to a list of arguments. This is done using the following syntax:
print("We'd have {} beans, {} jars, and {} crates.".format(*secret_formula(start_point)))
The important par is the * character. It tell that you want to convert the following iterable into a list of argument to pass to the function.