Cannot get Couchbase Lite Regex query to work

Mobile Couchbase Lite
1

I have a simple document structure where a number of locations of different types are held (with GPS location and name).
An example:

{
  "ispublic": true,
  "key": "8641",
  "name": "Grærup Langsø",
  "points": [
    {
      "lat": 55.6529802987,
      "lon": 8.1668484987
    },
    {
      "lat": 55.6563176391,
      "lon": 8.167440034
    },
    {
      "lat": 55.6518253871,
      "lon": 8.167535358
    }
  ],
  "type": "Lake"
}

If the user has not allowed the app to use the GPS then the user needs to search for the location (where he is fishing). So I have created this condition:

_condition = Expression.Property("name").Regex(Expression.String(search + ".*/i"))
    .And(Expression.Property(TYPE).EqualTo(Expression.String(typeof(Lake).Name))
        .Or(Expression.Property(TYPE).EqualTo(Expression.String(typeof(PutTakeLake).Name)))
        .Or(Expression.Property(TYPE).EqualTo(Expression.String(typeof(CoastLocalArea).Name)))
        .Or(Expression.Property(TYPE).EqualTo(Expression.String(typeof(SeaLocalArea).Name)))
        .Or(Expression.Property(TYPE).EqualTo(Expression.String(typeof(Stream).Name)))
        .Or(Expression.Property(TYPE).EqualTo(Expression.String(typeof(Country).Name))));

It includes all types of locations and tries to find the ones with a name that start with the letters entered by the user. But it does not match any names…

If I use

Expression.Property("name").Like(Expression.String(search + "%"))

Then it does match if I use the exact case “Gr” - but not “gr” (which it actually should according to the description and examples in: https://docs.couchbase.com/couchbase-lite/2.6/csharp.html#wildcard-match).

I have tried all sorts of different syntax attempts with the regex - but to no avail. I need to add the “/i” option to perform a case insensitive search. Attempts I have tried:

"gr/i"
"gr.*/i"
"/gr/i"
"gr\\/i"
"gr\\i"

And more (just pure wild shooting)…
Can anyone direct me to the right syntax

2

Ok, found out that the documentation is wrong. According to this post (that I did not find at first) Like is now case sensitive…

Using the suggestion to make all lower case seems to work.

Then I don’t need the Regex function - but would still be nice to know how the syntax should be when transforming from “standard regex” :wink:

3

We don’t have an API to pass through “regex flags” unfortunately. The regex will be applied via the C++11 regex class with the regex_constants::ECMAScript flag (Documentation on what that means can be found here. It does not accept flags on the end of the regex pattern.

1 Like
4

OK, thanks, Jim.

/John

5

We should probably improve the regex support to take into account the current collation. Then you can use the “collate” functionality in queries to control regex matching.

6

Well, it kind of fooled me… - but I guess if the case sensitivity issue in the doc for Likeis corrected then I wouldn’t even have looked at the Regex function :slight_smile:

7

Sorry about the incorrect documentation. We have a ticket filed to get it fixed.

1 Like