README.md

Feature Example - Default Values

This project demonstrates how to use default values for fields. It builds on the Task Manager starter project.

Instructions

To run this project, clone the Keystone repository locally then navigate to this directory and run:

yarn dev

This will start the Admin UI at localhost:3000. You can use the Admin UI to create items in your database.

You can also access a Apollo Sandbox at localhost:3000/api/graphql, which allows you to directly run GraphQL queries and mutations.

Features

This project demonstrates how to use default values for fields. Default values are set using the defaultValue argument on fields. They are applied by Keystone when an object is created and no value is supplied for the field. There are two types of default values in Keystone; static, and dynamic.

Static

Static default values are set using a fixed value as the defaultValue argument. We use a static default to set the isComplete state to false when a new task is created.

      isComplete: checkbox({ defaultValue: false }),

Dynamic

Dynamic default values are set using a function as defaultValue argument. This function is evaluated when the item is created. The function recieves two arguments, originalInput and context.

We use originalInput, which contains the input passed to the GraphQL create mutation, to set the priority of the task.

      priority: select({
        dataType: 'enum',
        options: [
          { label: 'Low', value: 'low' },
          { label: 'Medium', value: 'medium' },
          { label: 'High', value: 'high' },
        ],
        // Dynamic default: Use the label field to determine the priority
        defaultValue: ({ originalInput }) => {
          if (originalInput.label && originalInput.label.toLowerCase().includes('urgent')) {
            return 'high';
          } else {
            return 'low';
          }
        },
      }),

We use context along with the Query API to set the default assignee of a task to be a user named "Anonymous".

      assignedTo: relationship({
        ref: 'Person.tasks',
        many: false,
        // Dynamic default: Find an anonymous user and assign the task to them
        defaultValue: async ({ context }) => {
          const anonymous = await context.query.Person.findMany({
            where: { name: 'Anonymous' },
          });
          if (anonymous.length > 0) {
            return { connect: { id: anonymous[0].id } };
          }
          // If we don't have an anonymous user return undefined so as not to apply any default
        },
      }),