Same Table Backlinks

same-table-backlinks.js

/*****
 * Title: Same Table Backlinks
 * License: MIT
 * Author: Openside (Team behind On2Air products and BuiltOnAir community)
 * Sites:
 * https://openside.com - Openside Consulting Services
 * https://openside.com/#products - On2Air Products
 * https://builtonair.com - All things Airtable Community
 * 
 * Reach out for all your Airtable needs
 * 
 * Explainer Video: https://www.loom.com/share/9f90bb7bf95b4581a12a9750edb3a376
 * 
 * Description: Typically when creating a Linked Records to another table,
 * it will auto-create a field on the other table holding the backlinks back to the current table.
 * However, when creating links within the same table, it does not generate the 2nd backlink field.
 * 
 * This script will do that for you.  This is useful to see where a single table linked record field
 * is in use within the same field.
 * 
 * Instructions: Configure the links array below with the information to generate the links.
 * If no links are configured, it will ask for user input, so its ok to leave blank.
 * 
 * The 3 configuration items are:
 * table: The table name containing the linked record
 * view: (Optional) if set, then will filter records to check based on the view
 * source: The field name that is a linked record to the same table that is what
 * you are already updating. This field does not get modified.
 * dest: The destination field that will determine all the places each record is used as a source.
 * This field will get replaced each time script is ran
 * 
 */

//-------------START CONFIGURATION ------------------//

let links = [
    // {
    //     table:"Family Tree",
    //     view: '',
    //     source:"Parents",
    //     dest:"Children"
    // },
    // {
    //     table:"Family Tree 2",
    //     source:"Parents",
    //     dest:"Children"
    // }
]
//-------------END CONFIGURATION ------------------//

if(!links || !links.length){
    output.markdown("## Select Your Settings to Setup Children Links")
    let table = await input.tableAsync("Select The table")
    let source = await input.fieldAsync("Select The Source Field",table.id)
    let dest = await input.fieldAsync("Select The Destination Field",table.id)
    links.push({table:table.id,source:source.name,dest:dest.name})
}


const syncLinks = async( tableId, source, dest, viewName = '' ) => {
    
    let table = base.getTable(tableId)
    output.markdown(`#### Syncing - '${table.name}': '${source}' -> '${dest}'`)
    let view = viewName ? table.getView(viewName) : null
    let recordsFull = view ? await view.selectRecordsAsync() : await table.selectRecordsAsync()
    let records = recordsFull.records
    let len = records.length



    const findChildren = async() => {
        let tree = {}
        const setTree = ( parent, kid) => {
            if(!tree[parent])tree[parent] = []
            tree[parent].push({id:kid})
        }
        for(let t=0;t<records.length;t++){
            let rec = records[t]
            if (!tree[rec.id]) tree[rec.id] = []
            let parents = rec.getCellValue(source)
            if(!parents)continue;
            for(let p=0; p<parents.length; p++){
                
                setTree(parents[p].id, rec.id)

            }
        }
        output.text("------------------------------------")
        let parentKeys = Object.keys(tree)
        let queue = []
        for(let i=0; i<parentKeys.length; i++){
            let pKey = parentKeys[i]
            let pRecord = await recordsFull.getRecord(pKey)
            let kids = tree[pKey]
            
            if((!kids || kids.length === 0) && (!pRecord.getCellValue(dest) || pRecord.getCellValue(dest).length === 0))continue
            
            queue.push({id:pKey,fields:{[dest]: kids || []}})
            if(queue.length === 50){
                await table.updateRecordsAsync(queue)
                output.text("... "+(i+1))
                queue = []
            }
        }
        if(queue.length){
            await table.updateRecordsAsync(queue)
            output.text("... "+ parentKeys.length)
            queue = []
        }

    }
    await findChildren()

}

output.clear()
output.markdown("## Table Syncing Starting....")
for(let l=0; l<links.length;l++){
    let link = links[l]
    await syncLinks( link.table, link.source, link.dest, link.view || '' )
}
output.markdown("### Syncing Completed.")



//THIS WAS FOR GENERATING THE PARENT LINKS//TESTING ONLY//
// const getRandomInt = (max) => {
// return Math.floor(Math.random() * Math.floor(max));
// }
// const setParents = async() => {
//     for(let t=0;t<records.length;t++){
//         let rec = records[t]
//         let parents = []
//         let otherParent = -1
//         while(parents.length < 2){
//             let pIndex = getRandomInt(len)
//             if(pIndex != t && pIndex !== otherParent){//cant be your own parent or have 2 of same
//                 parents.push({id:records[pIndex].id})
//                 otherParent = pIndex
//             }
//         }
//         await table.updateRecordAsync(rec.id,{
//             [SOURCE_FIELD]:parents
//         })
//     }
// }
// //await setParents()

ERROR
TypeError: Cannot read properties of null (reading 'length')
at findChildren on line 96
at async syncLinks on line 112
at async main on line 120

@irenie-beanie try it now

Hi, I have what's probably a dumb question. I used this code in my Airtable script extension with no problem, but when I tried to build an Airtable automation, I get an error message that says "TypeError: output.clear is not a function" and the same thing for output.markdown. Any advice?

Any fix for this issue?

Error
TypeError: output.clear is not a function
at main on line 116

I am running this as part of an Automation

@on2air
Sorry to pester you - do you see any way to fix the error in my last comment?

Would there be a way to do this but have multiple sources linking to a single destination?

If I am reading this correctly, this will only create links, it won't delete them. So if you delete a link in record A pointing to B, then B's link back to A won't ever be deleted.

A fixed version of this that is intended for automations is in my gist here.