haystack-react/dist/useHaystackRecordTag.js

Project Haystack utilities for building React applications

/*
 * Copyright (c) 2021, J2 Innovations. All Rights Reserved
 */
import { useEffect, useState } from 'react';
import { useClient } from './client';
import { useWatch } from './watch';
/**
 * A hook to use a record tag from an haystack server as react state.
 *
 * IMPORTANT: writing is currently only supported with a FIN 5/SkySpark server.
 *
 * IMPORTANT: This hooks requires a ClientContext to work. @see https://github.com/j2inn/haystack-nclient
 *
 * @example <caption>Example of usage for a precision tag of type Number.</caption>
 *
 * const record = useReadByFilter('precision and point and temp and zone and sp').grid[0] // One-shot reading the first record that matches the filter
 * const [precision, setPrecision, updatedRecord] = useHaystackRecordTag<HNum>(record, "precision") // Using its tag state
 *
 * @param originalRecord record dict used to retrieve id and initial value.
 * @param tagName name of the tag.
 * @param pollRate poll rate for the value subscription. Expressed in seconds.
 * @returns Returns the point value, a function to update it and the point dict.
 */
export function useHaystackRecordTag(originalRecord, tagName, pollRate = 5) {
    const [currentValue, setCurrentValue] = useState();
    const [tagValue, record] = useReadHaystackRecordTag(originalRecord, tagName, pollRate);
    const write = useWriteHaystackRecordTag(originalRecord?.id, tagName);
    const writeFunc = write
        ? async (val) => {
            const result = await write?.(val);
            setCurrentValue(val);
            return result;
        }
        : undefined;
    useEffect(() => {
        setCurrentValue(tagValue);
    }, [tagValue]);
    return [currentValue, writeFunc, record];
}
function useReadHaystackRecordTag(originalRecord, tag = '', pollRate = 5) {
    const { grid: [record], isLoading, } = useWatch({
        ids: originalRecord?.id,
        pollRate: pollRate,
    });
    return isLoading
        ? [originalRecord?.get(tag), originalRecord]
        : [record?.get(tag), record];
}
function useWriteHaystackRecordTag(id, tag) {
    const client = useClient();
    return id && tag
        ? (val) => client.ext.eval(val != null
            ? `read(id==${id?.toAxon()}).diff({${tag}:${val.toAxon()}}).commit`
            : `read(id==${id?.toAxon()}).diff({-${tag}}).commit`)
        : undefined;
}
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