Working with JSON

With some databases, Metabase can unfold JSON columns into their component fields, which you can then filter on using the query builder.

Here is a table with a column that contains JSON.

Metabase can unfold that JSON column so that each key in the JSON object gets its own column in the table. Here are the unfolded fields of the table with the JSON column pictured above:

And here are the values as seen in the table:

This unfolding allows you to filter for values found in the original JSON object.

Metabase will prefix the unfolded column names with the name of the original column that contained the JSON. You can change the column names in Admin settings > Table metadata, or by creating a model and editing the column metadata.

Toggling JSON unfolding for a database

If you notice a hit to performance from this JSON unfolding, we recommend turning it off.

To turn off JSON unfolding for a database:

1. Click on the Gear in the upper right.
2. Select Admin settings
3. Visit the Databases tab.
4. Select the relevant database.
5. Click Show advanced options.
6. Toggle Allow unfolding of JSON columns.
7. Scroll down and click the Save changes button.
8. Click Sync database schema now.
9. Click Re-scan field values now.

Toggling JSON unfolding for a specific column

If performance degrades, or you’d rather keep the JSON contained in the original column, you can turn off unfolding for individual fields in their settings.

1. Click on the Gear in the upper right.
2. Select Admin settings.
3. Visit the Table metadata tab.
4. Select the database that contains the field you want to update.
5. Select the table that contains the field.
6. Select the field containing the original JSON
7. Scroll to the Unfold JSON option and select Yes or No. If the column was unfolded, Metabase will have hidden this JSON columnn from view, so if you want the JSON column to be visible again, you’ll need to change the column’s visibility to Everywhere.
8. Scroll down and click on the Re-scan this field.

For JSON unfolding to work, the column’s data type must be JSON

For example, if you upload a CSV with JSON in it, you might need to update the data/type in the database. Note that you can’t edit the data type via Metabase; you can only change its field type. So even if the field type in Metabase is Field containing JSON, if the data/type isn’t JSON, Metabase won’t give you the option to unfold the column. You’ll need to change the column type in the database itself.

Databases that support JSON unfolding

• PostgreSQL
• MySQL