Data model: objects, fields and relationships

Database words and Salesforce words

Common field types

Lookup versus master-detail

Objects and fields

Step 1: create the Menu Item object

1. 1Click the gear icon, choose Setup, open Object Manager.
2. 2Click Create, then Custom Object.
3. 3Label: Menu Item. Plural Label: Menu Items. The Object Name fills in as Menu_Item.
4. 4Record Name: label Menu Item Name, data type Text.
5. 5Under Optional Features, tick Allow Reports and Allow Search. Leave Deployment Status as Deployed.
6. 6Under Object Creation Options, tick Launch New Custom Tab Wizard after saving this custom object, and click Save.
7. 7In the tab wizard, choose any tab style and finish. A tab lets users open the object from the navigation bar.

Step 2: add fields to Menu Item

1. 1In Object Manager, open Menu Item, then Fields & Relationships, then New.
2. 2Choose Picklist, label Category, enter the values Coffee, Tea, Bakery, Food (one per line). Next, accept the field-level security defaults, and add the field to the default page layout. Save.
3. 3Create a Currency field labelled Price, length 6 and decimal places 2.
4. 4Create a Checkbox field labelled Available with default value Checked.

Step 3: create Coffee Order and Order Item

1. 1Create a custom object Coffee Order (plural Coffee Orders). For Record Name choose data type Auto Number, display format ORD-{0000}, starting number 1. Tick Allow Reports, Allow Activities and Allow Search, and save with a tab.
2. 2Add to Coffee Order a Lookup field to Contact, labelled Customer. Add a Picklist Status with the five values in the table. Add a Date/Time field Pickup Time.
3. 3Create a second custom object Order Item (plural Order Items) with Record Name type Auto Number and format OI-{0000}. Tick Allow Reports.
4. 4On Order Item, create a field of type Master-Detail Relationship. Choose Coffee Order as the related object. Accept the defaults. The field is labelled Coffee Order. Name it with the API name Coffee_Order__c.
5. 5Create a Lookup Relationship field from Order Item to Menu Item. Save.
6. 6Add Number field Quantity (length 3, 0 decimal places) and Currency field Unit Price (6, 2).
7. 7Add a Formula field Line Total. The return type is Currency with 2 decimal places, and the formula is Quantity__c * Unit_Price__c. Use Check Syntax, then save.

Step 4: add a roll-up summary on Coffee Order

1. 1Open the Coffee Order object, then Fields & Relationships, New.
2. 2Choose Roll-Up Summary and click Next. Label it Total.
3. 3Choose the summarised object Order Items, roll-up type SUM, field to aggregate Line Total.
4. 4Under filter criteria choose All records should be included in the calculation, and save. Make the field visible when asked.

Step 5: build an app and add data

1. 1In Setup, type App Manager in Quick Find, click New Lightning App.
2. 2Name it Brew and Bean, accept defaults through the wizard, and in Navigation Items add Menu Items, Coffee Orders, Order Items and Contacts. Add your user profile on the User Profiles step and save.
3. 3Open the app from the App Launcher. Under Menu Items, create Espresso (Coffee, 120), Cappuccino (Coffee, 180) and Butter Croissant (Bakery, 150).
4. 4Create a contact (or use Asha Rao). Create a Coffee Order with that customer, status Received.
5. 5On the order's page, in the Order Items related list, click New. Pick Espresso, quantity 2, unit price 120. Then add Butter Croissant, quantity 1, unit price 150.
6. 6Refresh the order. Total should read 390.

Data model checklist

1. Check for a standard object first before creating a custom one.
2. Use picklists instead of free text where values are a fixed list.
3. Choose master-detail only when the child cannot exist without its parent.
4. Prefer formula fields to storing values you can calculate.
5. Write clear labels, and add field descriptions and help text for admins and users.
6. Remember the API name, because Flow, SOQL and Apex all use it.