Custom Fields allows you to edit any Metafield, even if it wasn't created by our app. This is provided for convenience and to ease any transition from another Metafield app to ours.
We always recommend using our structured field types rather than "raw" Metafields, but sometimes that's not practical.
Creating Consistent Form Fields for Existing Metafields
Without any setup, the app will show metafields that have values already. When transitioning from another Metafield app to Custom Fields, oftentimes merchants would like to continue to use their existing namespaces and keys, since their theme is already built and running using those namespaces and keys. Custom Fields will allow you to define your existing fields from other apps so you can continue to use them while transitioning to Custom Fields. This allows your administrators to enter data without needing to remember the namespaces and keys when entering the data on a new product, for example.
To set up consistent form fields for your existing metafields, click the Gear icon in the top right, then open "Other Metafields", then "Specify Other Metafield Namespaces and Keys"
Here you can create form fields that will always appear in the Other Metafields section when editing a resource.
To do so, set namespace/key pairs that you want to show up for each resource type. For example, let's say you had an existing string field on products called "Extra Info" and you accessed it from product.metafields.c_f.extra_info in your liquid templates. You would represent this field in the form as one line: c_f.extra_info.string|Extra Info|Use this to show extra info.
NAMESPACE.KEY.VALUE_TYPE|Field Label|Optional description to show custom_namespace.custom_key.string|My Field Label
Example: c_f.dimension_w.integer|Dimensions (W)|Enter the product width in inches.
Note: If you don't provide a value type, "string" will be assumed. If you don't provide a field label, the namespace/key will be used as the field label. Valid value types include integer, string, and json_string.
The above configuration would produce the form below.
Additional Resources and Information
Custom Fields: Using Custom Fields Beyond Products - This section goes through different uses of Custom Fields other than product pages.