Data Modeling

Property prefix

User properties cannot begin with an underscore (_).

The underscore character (_) is a reserved prefix for system properties of a document (_id, _rev etc.) A document which contains user properties with a leading underscore will be rejected by Sync Gateway with the following error.

"{"error":"Bad Request","reason":"user defined top level properties beginning with '_' are not allowed in document body"}"

This rule applies to writes performed through Couchbase Lite SDKs and Sync Gateway REST APIs. And to writes performed through Couchbase SDKs when Mobile-Web Data Sync is enabled.

This may be an issue in the following scenarios:

In a deployment with Mobile-Web Data Sync and Field Level Encryption enabled, this rule conflicts with the default java-sdk::encryption.adoc#format.
Ottoman.js adds an _type attribute to the root of the document. So if you are using Ottoman within your app, then you would encounter this issue.

Note that in a deployment with Mobile-Web Data Sync and Field Level Encryption enabled, this rule conflicts with the default java-sdk::encryption.adoc#format.

Workaround

The recommended workaround in these scenarios is to wrap the property prefixed with an underscore in another object whose key isn’t prefixed with an underscore.