#Query Signals

Query signals in TeamPlay represent the result of a query on a collection. They are created using the sub() function or useSub() hook with query parameters.

#Creating a Query Signal

const $activeUsers = await sub($.users, { status: 'active' })

#Properties and Methods

#ids

A signal containing an array of IDs for the documents in the query result.

const userIds = $activeUsers.ids.get()

#extra

A signal containing extra query metadata returned by the server, such as count metadata.

const extra = $activeUsers.extra.get()

#getIds()

Returns an array of ids for the query results.

const ids = $activeUsers.getIds()

The result is always a string[]. Non-string ids are filtered out.

#getExtra()

Returns extra query metadata.

const extra = $activeUsers.getExtra()

For query signals, this is equivalent to $activeUsers.extra.get(). For aggregation signals, getExtra() returns the aggregation rows, the same value as .get().

#map(callback)

Maps over the documents in the query result.

const userNames = $activeUsers.map($user => $user.name.get())

#reduce(callback, initialValue)

Reduces the documents in the query result to a single value.

const totalAge = $activeUsers.reduce(($user, total) => total + $user.age.get(), 0)

#find(predicate)

Finds the first document in the query result that satisfies the predicate.

const $firstAdminUser = $activeUsers.find($user => $user.role.get() === 'admin')

#Iteration

Query signals are iterable, allowing you to use them in for...of loops:

for (const $user of $activeUsers) {
  console.log($user.name.get())
}

#Notes

• Query signals are reactive. Changes to the underlying data or to the query result will automatically update components using the query signal.
• The documents within a query signal are themselves signals, allowing for nested reactivity.
• For public documents in query results, configured identity fields are available in get() results and match the document id. idFields defaults to ['_id'].
• ids and extra are reserved metadata properties on query signals. Use the collection path, such as $.users['ids'], when you need a document whose id has one of those names.