OpenAPI description is missing the default value of postgres columns(?)

[fjf2002]

Hello, great work! I'm currently getting to know postgrest, and considering it for my project as a slim "application server" replacement.

Environment

• PostgreSQL version: docker image 13

• PostgREST version: docker image v7.0.1

• Operating system: ubuntu 20.04 on WSL2

Description of issue

Expected behavior vs actual behavior

When a postgres column has a default value, I would wish that the OpenAPI description reflects that (which currently does not seem to be the case?).

Steps to reproduce

CREATE TABLE t (i int DEFAULT 42)

See https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.0.2.md : I would have expected the following:

default - The default value represents what would be assumed by the consumer of the input as the value of the schema if one is not provided. Unlike JSON Schema, the value MUST conform to the defined type for the Schema Object defined at the same level. For example, if type is string, then default can be "foo" but cannot be 1.

[laurenceisla]

Hello! I've checked, and the default value can be found in the definitions section:

{
  "definitions": {
    "t": {
      "properties": {
        "i": {
          "default": 42,
          "format": "integer",
          "type": "integer"
        }
      },
      "type": "object"
    }
  }
}

Is this what you're looking for? If so, maybe the schema needed a reload before making the request again.

[fjf2002]

Thanks. Sorry, that was my fault.

[fjf2002]

Wait a second...
defaults still seem to be missing for data types text, date and time:

CREATE TABLE pvz.newtable (
	name text NOT NULL DEFAULT 'Sepp'::text,
	anzahl int4 NULL DEFAULT 42,
	rate float4 NULL DEFAULT 1.34,
	isvalid bool NOT NULL DEFAULT true,
	datum date NULL DEFAULT '1900-01-01'::date,
	zeit time NULL DEFAULT '13:37:00'::time without time zone,
	CONSTRAINT newtable_pk PRIMARY KEY (name)
);

... yields the following spec:

"definitions": {
    "newtable": {
      "required": [
        "name",
        "isvalid",
        "famstand"
      ],
      "properties": {
        "name": {
          "format": "text",
          "type": "string",
          "description": "Note:\nThis is a Primary Key.<pk/>"
        },
        "anzahl": {
          "default": 42,
          "format": "integer",
          "type": "integer"
        },
        "rate": {
          "default": 1.34,
          "format": "real",
          "type": "number"
        },
        "isvalid": {
          "default": true,
          "format": "boolean",
          "type": "boolean"
        },
        "datum": {
          "format": "date",
          "type": "string"
        },
        "zeit": {
          "format": "time without time zone",
          "type": "string"
        }
      },
      "type": "object"
    },

[fjf2002]

Any fixes or at least a confirmation of the problem here?
Thank You.

[laurenceisla]

@fjf2002 I was checking, and the schema cache shows the default value as: 'Sepp'::text for the name column, for instance.

postgrest/src/PostgREST/OpenAPI.hs

Lines 108 to 110 in 9568c46

	s =
	(mempty :: Schema)
	& default_ .~ (JSON.decode . toS =<< colDefault c)

Here, it's decoded, but it looks like it returns Nothing for that kind of default values (the ones with explicit casting), that's why it doesn't show when accessing the OpenApi endpoint.

That would be a starting point to solve the issue, but for now we are mostly concentrating our efforts on the next v8 release.

[fjf2002]

@laurenceisla thank you for your investigation. I'm afraid my haskell knowledge probably does not suffice to solve it on my own. Good luck on v8 release.

[wolfgangwalther]

Here, it's decoded, but it looks like it returns Nothing for that kind of default values (the ones with explicit casting), that's why it doesn't show when accessing the OpenApi endpoint.

I understand this is a bug then?