LWC Datatable Filtering with Infinite Scrolling?

Question:

I’m struggling to filter my Lightning Web Component (LWC) datatable while using infinite scrolling. When applying a filter, the component seems to duplicate rows and also fails to trigger the onloadmore event for infinite scrolling.

I have a custom datatable that loads an initial set of five records from a Custom Metadata Type. When more space becomes available, it dynamically fetches additional records up to a 200px height limit. This works as expected.

For filtering, I’m using an open-source child component (lwc-dynamic-datatable-filter). However, after applying a filter, duplicate rows appear, and infinite scrolling stops working.

Here’s my handleLoadMoreData method:

handleLoadMoreData(event) {
    console.log('in the handleMore function!');
    
    if(event.target){
        event.target.isLoading = true;
    }

    this.tableElement = event.target;
    this.loadMoreStatus = 'Loading';
    this.queryOffset = this.queryOffset + this.queryLimit;
    
    console.log('Query Limit:', this.queryLimit);
    console.log('Query Offset:', this.queryOffset);

    getMetadata({ 
        loadedPicklist: this.loadedPicklist, 
        offsetRecords: this.queryOffset, 
        limitRecords: this.queryLimit 
    })
    .then((data) => {
        this.data = [...this.data, ...data];  // Append new records
        this.loadMoreStatus = '';
        if (event.target) {
            event.target.isLoading = false;
        }
    })
    .catch(error => {
        console.error('Error loading more data:', error);
    });
}

How can I properly filter my datatable while ensuring that infinite scrolling continues working?

Answer:

Filtering an LWC datatable while using infinite scrolling can cause issues like row duplication or breaking the onloadmore event. The key is to properly manage the dataset by resetting it before filtering, applying filters locally, or refetching fresh data while maintaining pagination. These solutions ensure a smooth user experience without disrupting infinite scrolling functionality.

Boost your career with CRS Info Solutions’ Salesforce training , offering expert guidance, practical experience, and comprehensive knowledge—enroll for a free demo now!!!

The issue likely arises because filtering modifies the dataset while infinite scrolling appends to it, causing unexpected behaviors like row duplication or stopping the onloadmore event.

Solution 1: Reset Data on Filtering

Resetting data before applying a filter ensures that outdated records are removed, preventing duplication and conflicts with infinite scrolling. By clearing the dataset and resetting pagination (queryOffset), the component fetches fresh records that match the new filter criteria. This approach maintains data integrity while allowing smooth transitions between different filter selections.

Modify your filter handler to reset data before refetching:

handleFilterChange(event) {
    this.queryOffset = 0;  // Reset pagination
    this.data = [];  // Clear previous data
    this.loadMoreStatus = '';

    let selectedFilters = event.detail.filters;  // Get filter values
    this.applyFilters(selectedFilters);
}

Explanation: This function handles filter changes by resetting the dataset and pagination to ensure fresh data is loaded. It first clears queryOffset and data, preventing old records from persisting, and resets loadMoreStatus to enable proper UI updates. Finally, it retrieves the selected filters from the event and applies them using applyFilters().

Solution 2: Apply Filtering on Already Fetched Data

Filtering on already fetched data improves performance by avoiding unnecessary server calls and ensuring smooth infinite scrolling. By maintaining a copy of the full dataset (fullData), filters can be applied dynamically without affecting pagination. This approach enhances user experience by delivering instant results while keeping the data handling efficient.

applyFilters(selectedFilters) {
    this.data = this.fullData.filter(record => {
        return selectedFilters.every(filter => 
            record[filter.api] === filter.value
        );
    });
}

Explanation: The applyFilters function filters fullData based on selectedFilters, updating this.data with matching records. It uses every to ensure all conditions are met, checking if each record’s field (record[filter.api]) equals the corresponding filter value. This approach efficiently applies multiple filters without modifying the original dataset.

Solution 3: Fetch Fresh Data on Filtering

This solution involves fetching new records from the server whenever a filter is applied, ensuring that the data is accurately updated based on the selected criteria. By resetting the data and pagination offset, you can avoid conflicts between filtering and infinite scrolling. It guarantees that the latest data is always reflected in the datatable after each filter change.

handleFilterChange(event) {
    this.queryOffset = 0; 
    this.data = [];  
    this.loadMoreStatus = '';

    let selectedFilters = event.detail.filters;
    
    getMetadata({ 
        loadedPicklist: this.loadedPicklist, 
        offsetRecords: this.queryOffset, 
        limitRecords: this.queryLimit, 
        filters: selectedFilters 
    })
    .then(data => {
        this.data = data;
    })
    .catch(error => {
        console.error('Error fetching filtered data:', error);
    });
}

Explanation: The handleFilterChange method resets the data and query offset whenever a filter is applied, ensuring that new filtered data is fetched. It then calls the getMetadata Apex method with the current filters, offset, and limit to retrieve the data. Upon successful retrieval, the data is updated; otherwise, any errors are logged to the console.

Each of these solutions addresses different scenarios. Resetting data before filtering is the simplest fix, but if filtering should happen locally, maintaining an unfiltered dataset (fullData) is ideal.

Summing Up

LWC datatable filtering with infinite scrolling enables dynamic data fetching as users apply filters and scroll, improving performance by loading only relevant data. The combination of real-time filtering and pagination ensures seamless user experience without overwhelming the UI. By resetting the data and offset with each filter change, it ensures fresh and accurate results while maintaining smooth scrolling behavior.

Salesforce Training in Jaipur: Unlock Your Career Potential

Transform your career with comprehensive Salesforce training in Jaipur . Our expertly crafted program covers Admin, Developer, and AI tracks, combining in-depth modules, real-world projects, and interactive sessions to help you master Salesforce. Designed to prepare you for certifications, interviews, and a thriving career in the tech industry, our training ensures you’re industry-ready.

Join our free demo class to experience a hands-on, practical approach to learning.  Guided by seasoned professionals, you’ll effortlessly navigate even the most advanced Salesforce concepts. Whether you’re a beginner or seeking to elevate your expertise, our training equips you with the skills to solve real-world problems and excel in your field.

Don’t wait—enroll in our free demo today and take the first step toward a successful Salesforce career!!!

Related Posts:

• What are Lightning Web Components?
  
• Attributes and Properties in LWC