unable to query alerts api for more than 2 tags. / params

[streaming-pete]

Issue Summary
When trying to filter results via the API (or UI) using tags, we are unable to use more than 2 tags.

Environment

• OS: Linux

• API version: 9.0.1

• Deployment: Local / K8s

• For self-hosted, WSGI environment: nginx / pycharm

• Database: Postgres & Mongo

• Server config:
  Auth enabled? Yes for Prod, No for Dev
  Customer views? No

• web UI version: n/a

• CLI version: n/a

To Reproduce
Steps to reproduce the behavior:
create 3 alerts with unique tags. eg
alerta send -r test4 -e test4 -S test4 -t test4 -T dc=tag1 -E Production -s major
alerta send -r test3 -e test3 -S test3 -t test3 -T dc=tag2 -E Production -s major
alerta send -r test2 -e test2 -S test2 -t test2 -T dc=tag3 -E Production -s major

query api with following params

/alerts?q=tags%3A"dc%3Dtag1"+tags%3A"dc%3Dtag2"+tags%3A"dc%3Dtag3"

response will only be for tag1 + tag2.

code generates: "('dc=tag1'=ANY("tags") OR 'dc=tag2'=ANY("tags"))"

Expected behavior
all tags in search returned

"('dc=tag1'=ANY("tags") OR 'dc=tag2'=ANY("tags") OR OR 'dc=tag3'=ANY("tags"))"

Screenshots

Additional context
This was a customer request from our ops dept using alerta.

I have done some debugging and testing against mongo and postgres, in debug mode I can trace the params correctly getting to the QueryParser class in queryparser.py and then hitting the query_expr infixNotation() that seems to only handle a left / right or clause. (Optional(OR).setParseAction(lambda: 'OR'), 2, opAssoc.LEFT, SearchOr), this in turn returns an sql query of:

"('dc=tag1'=ANY("tags") OR 'dc=tag2'=ANY("tags"))"

so it looks like the parser for handling multiple query params is locked at 2 even though 3 params were passed into the function.

Appreciate any feedback or guidance on what we could do here to open this up to more parameters for searching.

Thanks
Pete

[streaming-pete]

Interestingly, I can get up to 4 working by wrapping 2 sets of OR's in brackets via the UI. (I have moved to the tag called channel here which are in my prod system i have lots alerts for)

(tags:"channel=channel010" tags:"channel=channel004") (tags:"channel=channel001" tags:"channel=channel018") = 4 valid alerts

and this seems to continue by wrapping that 4 queries in brackets also works for fulfilling the first OR in the query, this will probably continue forever and is becoming a little unintuitive for the user.

((tags:"channel=channel010" tags:"channel=channel004") (tags:"channel=channel001" tags:"channel=channel018")) (tags:"channel=channel022")` = 5 valid alerts

and a full 11 example..
(((tags:"channel=channel010" tags:"channel=channel023") (tags:"channel=channel018" tags:"channel=channel001")) ((tags:"channel=channel053" tags:"channel=channel049") (tags:"channel=channel062" tags:"channel=channel004"))) (((tags:"channel=channel022" tags:"channel=channel022") (tags:"channel=channel019" tags:"channel=channel005")))