Help creating new Development Mode Synced realm

I’ve got an iOS (swift) app that’s using a local realm. I’m trying to update it to use a synced realm so eventually I can make my app multi-user and share data. But I am new to MongoDB and Synced Realms.

I’ve successfully installed/build/run the “TaskTracker” starter “Synced” app on atlas and an iOS client.

Now I’m trying to make a Synced Realm for my app. I figure I would create a Synced Realm and put it in Development mode from scratch. That way I can convert my existing data into Synced data bit by bit and I don’t have to worry about the server side schema yet. I’m hoping that the schema will be defined for me and I can use it once I’m ready to move to a production level deployment.

So, I’m following the “Get Started with Sync” document ( I’ve created my Atlas Cluster (Cluster0), and a Realm app in the web UI. The document says:

  1. Navigate to the Realm Sync Panel
  2. Decide whether to use Development Mode (I am).
  3. Configure Sync:

In this step in the web UI, it seems that there are 3 steps:

  1. Select a Cluster to Sync
  2. Choose a Partition Key
  3. Define a Database Name

For Step 1, I can select “Cluster0 - (Service: mongodb-atlas)”

However in Step 2 is where I get stuck: There is a dropdown that says “Enter a partition key field name…”, but when I select the drop down, it says “No options” and I cannot select anytthing. Therefore I can’t go to the third step or turn dev mode on.

The “Get Started with Sync” document doesn’t say anything about pre-populating the realm with data or schema (I thought that’s why I’m choosing Development Mode, so I can define my data on the fly until I figure out what the schema should be).

I’m super stuck here. It’s likely because I don’t understand something. Can someone help me see the light?


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Hm. I thought it might be that I was missing a database in the atlas cluster, but even after creating it (and a Collection), it still doesn’t work. bummer.

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You should be able to type in the name of the desired partition key. The suggestions in the dropdown are populated based on any existing data in your cluster. I’m guessing there is no data yet.

We’ll update the docs to make this clearer!


Thanks Chris. So does this mean there must be pre-existing data? What if I don’t have any data because I’m trying to setup a brand new Synced Realm with Development mode turned on?

The docs imply that Development mode can be used to setup a new synced realm so we can define the data and schema on the fly on the client, then when we’re ready to go to production, we’d take the configured schema and deploy it in a non-development mode.

Requiring pre-existing data in the mongo cluster seems to defeat the purpose of development mode.

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No, there does not need to be pre-existing data. On that screen, instead of using the dropdown, you can type in whatever field name you intend to use for the partition value. We generally use _partition. Hope this helps!


ARGH. OK. I completely didn’t realize that you could type in that field. I thought i had to select something from the dropdown (which didn’t have any options). :man_facepalming:

Thank you.


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