Setting default values for fields using Postgres defaults

You can set values of certain fields automatically when not explicitly passed to a fixed value, e.g. true for a boolean field, or output of a simple SQL function, e.g. now() for a timestamp field, by setting column default values in the table definition.

Note

The Postgres default value is ignored when a value is explicitly set to the field.

Example: Say we have a field created_at in a table article which we want to be set to the current timestamp whenever a new row is added to the table:

Step 1: Modify the table

Edit the created_at field and set its Default value as the SQL function now().

Open the console and head to Data -> article -> Modify:

To set an auto-incrementing default value

To set a default value as an auto-incrementing integer you first need to set up a sequence which will be the source of our default value.

Let’s say we have a field called roll_number which we would like to be set by default as an auto-incremented integer.

Head to Data -> SQL and run the following SQL command to create a new sequence.

CREATE SEQUENCE roll_number_seq;

Now set the default value of the roll_number field as nextval('roll_number_seq').

Step 2: Run an insert mutation

Now if you do not pass the created_at field value while running an insert mutation on the article table, its value will be set automatically by Postgres.