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useQuery()

Data rendering without the fetch.

Access any Queryable Schema's store value; like Entity, All, Collection, Query, Union, and Scalar. Lazy fields also work via their .query accessor. If the value does not exist, returns undefined.

useQuery() is reactive to data mutations; rerendering only when necessary. Returns undefined when data is Invalid.

tip

Queries are a great companion to efficiently render aggregate computations like those that use groupBy, map, reduce, and filter.

Usage​

<script setup lang="ts">
  import { Query } from '@data-client/rest';
  import { useQuery } from '@data-client/vue';
  import { PostResource } from './PostResource';

  const queryTotalVotes = new Query(
    PostResource.getList.schema,
    posts => posts.reduce((total, post) => total + post.votes, 0),
  );

  const props = defineProps<{ userId: number }>();
  const totalVotes = useQuery(queryTotalVotes, { userId: props.userId });
</script>

<template>
  <center>
    <small>{{ totalVotes }} votes total</small>
  </center>
</template>

See truthiness narrowing for more information about type handling

Types​

function useQuery<S extends Queryable>(
  schema: S,
  ...args: MaybeRefsOrGetters<SchemaArgs<S>>
): ComputedRef<DenormalizeNullable<S> | undefined>;

Arguments can be plain values or refs (including computed); the result updates when they change.

Queryable​

Queryable schemas require an queryKey() method that returns something. These include Entity, All, Collection, Query, Union, and Scalar. Lazy fields produce a Queryable via their .query accessor.

interface Queryable {
  queryKey(
    args: readonly any[],
    queryKey: (...args: any) => any,
    getEntity: GetEntity,
    getIndex: GetIndex,
    // Must be non-void
  ): {};
}

Examples​

Sorting & Filtering​

Query provides programmatic access to the Reactive Data Client store.

<script setup lang="ts">
  import { Query, All } from '@data-client/rest';
  import { useQuery, useFetch } from '@data-client/vue';
  import { UserResource, User } from './UserResource';

  interface Args {
    asc: boolean;
    isAdmin?: boolean;
  }
  const sortedUsers = new Query(
    new All(User),
    (entries, { asc, isAdmin }: Args = { asc: false }) => {
      let sorted = [...entries].sort((a, b) =>
        a.name.localeCompare(b.name),
      );
      if (isAdmin !== undefined)
        sorted = sorted.filter(user => user.isAdmin === isAdmin);
      if (asc) return sorted;
      return sorted.reverse();
    },
  );

  useFetch(UserResource.getList);
  const users = useQuery(sortedUsers, { asc: true });
</script>

<template>
  <div v-if="!users">No users in cache yet</div>
  <div v-else>
    <div v-for="user in users" :key="user.pk()">{{ user.name }}</div>
  </div>
</template>

Lazy relationships​

Lazy fields keep raw IDs during parent denormalization. Use .query with useQuery to resolve them on demand, isolating re-renders to only the components that need the related data.

<script setup lang="ts">
  import { computed } from 'vue';
  import { useQuery } from '@data-client/vue';
  import { Department } from './Resources';

  const props = defineProps<{ dept: Department }>();

  const buildings = useQuery(
    Department.schema.buildings.query,
    computed(() => props.dept.buildings),
  );
</script>

<template>
  <span v-if="buildings">{{ buildings.map(b => b.name).join(', ') }}</span>
</template>

<script setup lang="ts">
  import { All } from '@data-client/rest';
  import { useQuery, useFetch } from '@data-client/vue';
  import { DepartmentResource, Department } from './Resources';
  import BuildingList from './BuildingList.vue';

  useFetch(DepartmentResource.getList);
  const departments = useQuery(new All(Department));
</script>

<template>
  <div v-if="!departments">Loading...</div>
  <div v-else>
    <div v-for="dept in departments" :key="dept.pk()">
      <strong>{{ dept.name }}</strong>: <BuildingList :dept="dept" />
    </div>
  </div>
</template>