Query ArangoDB for Arrays - arangodb

Question

I am having a problem querying ArangoDB in java for a value of Arrays. I have tried with both String[] and ArrayList, both with no success.
My query:
FOR document IN documents FILTER #categoriesArray IN document.categories[*].title RETURN document
BindParams:
Map<String, Object> bindVars = new MapBuilder().put("categoriesArray", categoriesArray).get();
categoriesArray contains a bunch of Strings. I'm not sure why it isn't returning any results, because if I query using:
FOR document IN documents FILTER "Politics" IN document.categories[*].title RETURN document
I get the results I am looking for. Just not when using an Array or ArrayList.
I also tried querying for:
FOR document IN documents FILTER ["Politics","Law] IN document.categories[*].title RETURN document
in order to emulate an ArrayList, but this doesn't return any results. I would query using a bunch of individual Strings, but there are too many and I get an error from the Java driver when querying with a String that long. Thus, I must query using an Array or ArrayList.
An example of the categoriesArray:
["Politics", "Law", "Nature"]
A sample image of the database:

Answer 1

The reason is that the IN operator works by searching for the value on its left-hand side in each member of the array on the right side.
With the following the query, this will work if "Politics" is a member of document.categories[*].title:
FOR document IN documents FILTER "Politics" IN document.categories[*].title RETURN document
However the following will not work query even if "Politics" is a member of document.categories[*].title:
FOR document IN documents FILTER [ "Politics", "Law" ] IN document.categories[*].title RETURN document
This is because it will be searched for the exact value [ "Politics", "Law" ] in each member on the right side, and this will not be present. What you are probably looking for is a comparison that looks for "Politics" and "Law" separately, e.g.:
FOR document IN documents
LET contained = (
FOR title IN [ "Politics", "Law" ] /* or #categoriesArray */
FILTER title IN document.categories[*].title
RETURN title
)
FILTER LENGTH(contained) > 0
RETURN document

Answer 2

Arango also (now) has Array Comparison Operators which allow searching ALL IN, ANY IN, or NONE IN
[ 1, 2, 3 ] ALL IN [ 2, 3, 4 ] // false
[ 1, 2, 3 ] ALL IN [ 1, 2, 3 ] // true
[ 1, 2, 3 ] NONE IN [ 3 ] // false
[ 1, 2, 3 ] NONE IN [ 23, 42 ] // true
[ 1, 2, 3 ] ANY IN [ 4, 5, 6 ] // false
[ 1, 2, 3 ] ANY IN [ 1, 42 ] // true
[ 1, 2, 3 ] ANY == 2 // true
[ 1, 2, 3 ] ANY == 4 // false
[ 1, 2, 3 ] ANY > 0 // true
[ 1, 2, 3 ] ANY <= 1 // true
[ 1, 2, 3 ] NONE < 99 // false
[ 1, 2, 3 ] NONE > 10 // true
[ 1, 2, 3 ] ALL > 2 // false
[ 1, 2, 3 ] ALL > 0 // true
[ 1, 2, 3 ] ALL >= 3 // false
["foo", "bar"] ALL != "moo" // true
["foo", "bar"] NONE == "bar" // false
["foo", "bar"] ANY == "foo" // true
So you could now filter by:
FOR document IN documents
FILTER ["Politics", "Law] ANY IN (document.categories[*].title)[**]
RETURN document