contains() doesn't seem to work with custom string expression

[tomzorz]

Describe the bug

The ˙contains() function doesn't seem to work when using a string expression in it.

To Reproduce

1. Create a file with the tags #person and #date/08/06/1990 in it.

2. Create a second file with the following dataview query in it:

```dataview
LIST 
FROM #person
WHERE contains(file.tags, "#date/" + date(today).month + "/" + date(today).day)
```

The query today (August 6th) evaluates to the string #date/08/06 which is definitely contained in file.tags (which can be verified by using LIST file.tags FROM #person.)

I also tried wrapping "#date/" + date(today).month + "/" + date(today).day in a parenthesis, or adding it to an object and accessing it, e.g. object("today", "#date/" + date(today).month + "/" + date(today).day).today before using it as the 2nd param for contains(), but these attempts failed as well.

Expected behavior
The file created in step 1 shows up.

Actual behavior
The file doesn't show up.

Desktop (please complete the following information):

• OS: Windows 10 20H2
• Obsidian Version 0.12.10
• Dataview Version 0.4.3

[M-bot]

The query today (August 6th) evaluates to the string #date/08/06

The following string expression from the query you provided does not evaluate to that string
`="#date/" + date(today).month + "/" + date(today).day`
will evaluate to #date/8/6

The fields on date are all integers/numbers (not formatted strings) so when you add them to a string they do not have the extra zero. To get the query you want you need to use dateformat

The following query should work

```dataview
list
from #person
where contains(file.tags, "#date/"+dateformat(date(today), "MM/dd"))
```

You can find other format options in the luxon docs

[tomzorz]

Welp, you're completely right - I totally forgot about the leading zeroes. Thanks for pointing me towards the luxon docs!