How to use regex inside in query using morphia? - regex

Question

Mongodb allows regex expression of pattern /pattern/ without using $regex expression.
http://docs.mongodb.org/manual/reference/operator/query/in/
How can i do it using morphia ?
If i give Field criteria with field operator as in and value of type "java.util.regex.Pattern" then the equivalent query generated in
$in:[$regex: 'given pattern'] which wont return expected results at all.
Expectation: $in :[ /pattern1 here/,/pattern2 here/]
Actual using 'Pattern' object : $in : [$regex:/pattern1 here/,$regex:/pattern 2 here/]

Answer 1

I'm not entirely sure what to make of your code examples, but here's a working Morphia code snippet:
Pattern regexp = Pattern.compile("^" + email + "$", Pattern.CASE_INSENSITIVE);
mongoDatastore.find(EmployeeEntity.class).filter("email", regexp).get();
Note that this is really slow. It can't use an index and will always require a full collection scan, so avoid it at all cost!
Update: I've added a specific code example. The $in is not required to search inside an array. Simply use /^I/ as you would in string:
> db.profile.find()
{
"_id": ObjectId("54f3ac3fa63f282f56de64bd"),
"tags": [
"India",
"Australia",
"Indonesia"
]
}
{
"_id": ObjectId("54f3ac4da63f282f56de64be"),
"tags": [
"Island",
"Antigua"
]
}
{
"_id": ObjectId("54f3ac5ca63f282f56de64bf"),
"tags": [
"Spain",
"Mexico"
]
}
{
"_id": ObjectId("54f3ac6da63f282f56de64c0"),
"tags": [
"Israel"
]
}
{
"_id": ObjectId("54f3ad17a63f282f56de64c1"),
"tags": [
"Germany",
"Indonesia"
]
}
{
"_id": ObjectId("54f3ad56a63f282f56de64c2"),
"tags": [
"ireland"
]
}
> db.profile.find({ tags: /^I/ })
{
"_id": ObjectId("54f3ac3fa63f282f56de64bd"),
"tags": [
"India",
"Australia",
"Indonesia"
]
}
{
"_id": ObjectId("54f3ac4da63f282f56de64be"),
"tags": [
"Island",
"Antigua"
]
}
{
"_id": ObjectId("54f3ac6da63f282f56de64c0"),
"tags": [
"Israel"
]
}
{
"_id": ObjectId("54f3ad17a63f282f56de64c1"),
"tags": [
"Germany",
"Indonesia"
]
}
Note: The position in the array makes no difference, but the search is case sensitive. Use /^I/i if this is not desired or Pattern.CASE_INSENSITIVE in Java.

Answer 2

Single RegEx Filter
use .filter(), .criteria(), or .field()
query.filter("email", Pattern.compile("reg.*exp"));
// or
query.criteria("email").contains("reg.*exp");
// or
query.field("email").contains("reg.*exp");
Morphia converts this into:
find({"email": { $regex: "reg.*exp" } })
Multiple RegEx Filters
query.or(
query.criteria("email").contains("reg.*exp"),
query.criteria("email").contains("reg.*exp.*2"),
query.criteria("email").contains("reg.*exp.*3")
);
Morphia converts this into:
find({"$or" : [
{"email": {"$regex": "reg.*exp"}},
{"email": {"$regex": "reg.*exp.*2"}},
{"email": {"$regex": "reg.*exp.*3"}}
]
})
Unfortunately,
You cannot use $regex operator expressions inside an $in.
MongoDB Manual 3.4
Otherwise, we could do:
Pattern[] patterns = new Pattern[] {
Pattern.compile("reg.*exp"),
Pattern.compile("reg.*exp.*2"),
Pattern.compile("reg.*exp.*3"),
};
query.field().in(patterns);
hopefully, one day morphia will support that :)