shelving/db/store/QueryStore.js

Toolkit for using data in JavaScript.

import { RequiredError } from "../../error/RequiredError.js";
import { FetchStore } from "../../store/FetchStore.js";
import { getFirst, getLast } from "../../util/array.js";
import { getGetter } from "../../util/class.js";
import { NONE } from "../../util/constants.js";
import { getQueryLimit } from "../../util/query.js";
import { runSequence } from "../../util/sequence.js";
/** Store that queries multiple items in a collection from a database provider. */
export class QueryStore extends FetchStore {
    provider;
    collection;
    query;
    get limit() {
        return getQueryLimit(this.query) ?? Number.POSITIVE_INFINITY;
    }
    /** Can more items be loaded after the current result. */
    get hasMore() {
        return this._hasMore;
    }
    _hasMore = false;
    /** Get the first item in this store or `null` if this query has no items. */
    get optionalFirst() {
        return getFirst(this.value);
    }
    /** Get the last item in this store or `null` if this query has no items. */
    get optionalLast() {
        return getLast(this.value);
    }
    /** Get the first item in this store. */
    get first() {
        const first = this.optionalFirst;
        if (!first)
            throw new RequiredError(`First item does not exist in collection "${this.collection.name}"`, {
                store: this,
                provider: this.provider,
                collection: this.collection.name,
                query: this.query,
                caller: getGetter(this, "first"),
            });
        return first;
    }
    /** Get the last item in this store. */
    get last() {
        const last = this.optionalLast;
        if (!last)
            throw new RequiredError(`Last item does not exist in collection "${this.collection.name}"`, {
                store: this,
                provider: this.provider,
                collection: this.collection.name,
                query: this.query,
                caller: getGetter(this, "first"),
            });
        return last;
    }
    constructor(collection, query, provider, memory) {
        const items = memory?.getTable(collection).getQuery(query);
        super(items ?? NONE); // Use the current memory snapshot if available.
        if (memory)
            this.starter = store => runSequence(store.through(memory.getQuerySequence(collection, query)));
        this.provider = provider;
        this.collection = collection;
        this.query = query;
    }
    // Override to fetch the result from the database provider.
    _fetch(_signal) {
        return this.provider.getQuery(this.collection, this.query);
    }
    /**
     * Load more items after the last once.
     * - Promise that needs to be handled.
     * @todo Make this work.
     */
    // fetchMore(): void {
    // 	if (!this.busy.value) void this._fetchMore();
    // }
    // private async _fetchMore(): Promise<void> {
    // 	this.busy.value = true;
    // 	this.reason = undefined; // Optimistically clear the error.
    // 	try {
    // 		const last = this.last;
    // 		const query = last ? getAfterQuery(this.query, last) : this.query;
    // 		const items = await this.provider.getQuery(this.collection, query);
    // 		this.value = [...this.value, ...items];
    // 		this._hasMore = items.length >= this.limit; // If the query returned {limit} or more items, we can assume there are more items waiting to be queried.
    // 	} catch (thrown) {
    // 		this.reason = thrown;
    // 	} finally {
    // 		this.busy.value = false;
    // 	}
    // }
    // Implement `Iterable`
    [Symbol.iterator]() {
        return this.value.values();
    }
}