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Scripting Block Example - Project design tasks

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Attempting to test the sample Project design tasks block - get the following. Any ideas why?

The field is a string

Error: Can’t create records: invalid cell value for field ‘Design project’.
Cell value has invalid format: must be a string
at Mutations._assertMutationIsValid

5 Replies 5

Hi Doug – what’s the type of the “Design project” field in your table?

Could you also paste the script you’re running here for easier debugging

Thanks for the response. The script is the example from Fri’s webinar. All of the examples worked except for this one.

// pick tables from your base here
let projects = base.getTable('Design projects');
let tasks = base.getTable('Tasks');

// prompt the user to pick a template for our project
output.markdown('# New project');
let name = await input.textAsync('Project name');

// create the project - change the field name to one in your base
let projectId = await projects.createRecordAsync({
    'Name': name,

// create the tasks - change the field names to ones from your base.
// the [{id: projectId}] links the newly created records back to our project
await tasks.createRecordsAsync([
        fields: {
            'Name': 'The first task',
            'Design project': [{id: projectId}],
        fields: {
            'Name': 'Another task',
            'Design project': [{id: projectId}],
        fields: {
            'Name': 'The final task',
            'Design project': [{id: projectId}],


This is the tasks table

This is the error code

Error: Can't create records: invalid cell value for field 'Design project'.
Cell value has invalid format: <root> must be a string
    at Mutations._assertMutationIsValid (
    at Mutations.applyMutationAsync$ (
    at tryCatch (
    at Generator.invoke [as _invoke] (
    at Generator.prototype.<computed> [as next] (
    at tryCatch (
    at invoke (
    at new Promise (<anonymous>)
    at callInvokeWithMethodAndArg (


I believe you need to change your “Design project” field in the “Tasks” table to be a Link to another record type, and linked to your “Design projects” table.

Right now that field is just a text field, so it can’t establish a linked record.

The script worked perfectly when I did that.

Thank you

HI - Hey, I figured it out … thanks for the follow up