As an editor I want to query for data involving quantity values.
**Problem:**
We currently don't allow querying for values of Properties with datatype quantity. We should.
**Example:**
* people with an Erdős number of 1
**BDD**
GIVEN a visual query
WHEN selecting a Property of datatype quantity
THEN the value input accepts quality values
AND the query result contains only results including an exact match for the given value
**Acceptance criteria:**
[ ] queries with Properties of datatype quantity are possible
[ ] quantity values incl. and excl. units are possible
**Needed components:**
* [[ https://phabricator.wikimedia.org/T273001 | quantity input component ]]
**Notes:**
* We do not handle less than/more than etc. in this ticket, only exact matches. Ranges are handled in T272692.
* **Not dealing with precision at all**
The query that we're going to produce should look something like the following:
```
lang=sparql
SELECT ?person ?Erdos
WHERE {
?person p:P2021/psv:P2021/wikibase:quantityAmount ?Erdos .
FILTER( ?Erdos = 1)
}
LIMIT 3
```
https://w.wiki/34zj
The query if the user provides a unit:
```
lang=sparql
# convert kilometer into meter and then query
SELECT * WHERE {
BIND(4 AS ?userQuantity)
BIND(wd:Q828224 AS ?userUnit)
?userUnit p:P2370/psv:P2370 [
wikibase:quantityAmount ?conversionFactor;
wikibase:quantityUnit ?coherentUnit
].
BIND(?userQuantity * ?conversionFactor AS ?coherentQuantity)
?mountain p:P2044/psn:P2044 [
wikibase:quantityAmount ?elevation;
wikibase:quantityUnit ?coherentUnit
].
FILTER(?elevation >= ?coherentQuantity)
BIND(?elevation / ?conversionFactor AS ?userElevation)
}
LIMIT 10
```
https://w.wiki/34zm