We recently ran into a situation where we needed to rename a field in our Strapi content type from time_start to time_min but we had already created documents (records) in our Mongo Database for this content type that we need to preserve and we need to preserve the data. We were looking for a solution to change the field in our collection content type while also maintaining the data in the database. To prevent data loss, Strapi currently creates a new field in your database instead of overwriting the current field:

Strapi does not rename or drop anything it will only create at this time. Migrations need to be done manually.

This quick tutorial will walk you through updating a field in Strapi while preserving the data in your database.

Updating the Model Definition

In order to update the name of the field you will have to drill down into your api/<content-type>/models/<content-type>.settings.json file (replacing <content-type> with your content type and find the field in the attributes key that you want to edit. In our case, the field was named time_start.

"attributes": {
    "slug": {
      "type": "uid",
      "targetField": "name",
      "required": true
    },
    "time_start": {
      "type": "integer"
    },
}

Since we didn’t need to change the type of the field all we need to do here is rename the time_start key to time_min such that:

"attributes": {
    "slug": {
      "type": "uid",
      "targetField": "name",
      "required": true
    },
    "time_min": {
      "type": "integer"
    },
}

This tells Strapi that our field is now time_min however, this will create a new field in our Mongo database and the data in our mongo documents will still be left within the time_start field that we previously defined. We will need to manually update this field in our Mongo Database and rename all instances of time_start to time_min.

Renaming a Field in MongoDB

Fortunately, for us Mongo shell provides a quick and easy solution to rename all instances of a field in our mongo database. In this instance the $rename operator during an update() will be the solution of choice!

The $rename operator updates the name of a field and has the following form:

https://docs.mongodb.com/manual/reference/operator/update/rename/

{$rename: { <field1>: <newName1>, <field2>: <newName2>, ... } }

Considering our example we would need to update the collection (the name of our content-type) including all of the documents and renaming the field time_start to time_min. In our case our collection name is workouts so our command in our mongo shell would look like:

db.workouts.updateMany( {}, { $rename: { 'time_start': 'time_min' } } )

The updateMany will update the documents that meet the selector (the first argument in our updateMany method which in our case is an object so all of the documents will be updated. We are then using the $rename operator to rename the field from time_start to time_min which matches the name in our api/workout/models/workout.settings.json attributes field that we changed in the previous step.

Quick Summary

In order to change the field name in out Strapi content type and preserve the data we need to update your api/<content-type>/models/<content-type>.settings.json file to change the name of the field. Then we need to login to the mongo shell and use the updateMany method on our collection using the $rename operator to rename all instances of the field to the new name we defined in our model’s JSON settings.