iop-openapi: fix schema details with ref to component

In OpenAPI, components schemas can be declared independently, and then
referred to to avoid duplication.
However, when referencing an existing schema, no other information can
be provided. This means that a field of a struct whose type has its own
schema must use a '$ref', but then cannot specify anything else,
especially no default value, no description, no constraints...

This is a pretty bad overlook from the OpenAPI spec:
�ihttps://github.com/OAI/OpenAPI-Specification/issues/1514

The proposed workaround is to use an untyped schema with all the
details, and push the $ref inside an allOf clause, on its own.

This is what is done in this commit. As you can see, this is pretty bad
semantically, and I can't really imagine expecting a client to properly
understand what it means, but that's the solution...

Change-Id: Ifdba5fe6a7a2494aa136ec3ea3f0952edd45d6d0

iop-openapi.blk

@@ -578,28 +578,35 @@ static scalar_value_t *t_attr_get_value(const iop_field_attr_t *attr,
     return NULL;
 }
 
-static void
+static bool
 apply_raw_field_constraints(const iop_field_attrs_t *attrs,
                             const iop_field_t *field,
                             schema_object_t *schema)
 {
+    bool did_update = false;
+
     for (int i = 0; i < attrs->attrs_len; i++) {
         const iop_field_attr_t *attr = &attrs->attrs[i];
 
         switch (attr->type) {
           case IOP_FIELD_MIN:
+            did_update = true;
             schema->minimum = t_attr_get_value(attr, field->type);
             break;
           case IOP_FIELD_MAX:
+            did_update = true;
             schema->maximum = t_attr_get_value(attr, field->type);
             break;
           case IOP_FIELD_MIN_LENGTH:
+            did_update = true;
             OPT_SET(schema->min_length, attr->args[0].v.i64);
             break;
           case IOP_FIELD_MAX_LENGTH:
+            did_update = true;
             OPT_SET(schema->max_length, attr->args[0].v.i64);
             break;
           case IOP_FIELD_PATTERN:
+            did_update = true;
             schema->pattern = attr->args[0].v.s;
             break;
           default:
@@ -615,14 +622,18 @@ apply_raw_field_constraints(const iop_field_attrs_t *attrs,
           || schema->minimum->type == SCALAR_UINT64)
         &&  schema->minimum->i == 0)
         {
+            did_update = true;
             schema->minimum->i = 1;
         }
     }
     if (TST_BIT(&attrs->flags, IOP_FIELD_NON_EMPTY)
     &&  !OPT_ISSET(schema->min_length))
     {
+        did_update = true;
         OPT_SET(schema->min_length, 1);
     }
+
+    return did_update;
 }
 
 static void
@@ -678,6 +689,8 @@ t_get_iop_field_defval(const iop_field_t *desc)
         break;
 
       case IOP_T_ENUM:
+        /* FIXME: use string repr, as we type ENUM as string in the
+         * schema */
         val->i = desc->u0.defval_enum;
         val->type = SCALAR_INT64;
         break;
@@ -701,6 +714,7 @@ t_iop_field_to_schema_object(const iop_struct_t *st, const iop_field_t *desc,
     schema_object_t *schema;
     const iop_help_t *help;
     bool is_v2;
+    bool has_update = false;
 
     if (attrs && TST_BIT(&attrs->flags, IOP_FIELD_PRIVATE)) {
         return NULL;
@@ -778,7 +792,9 @@ t_iop_field_to_schema_object(const iop_struct_t *st, const iop_field_t *desc,
     }
 
     if (attrs) {
-        apply_raw_field_constraints(attrs, desc, schema);
+        has_update |= apply_raw_field_constraints(attrs, desc, schema);
+        /* FIXME: must transform the schema into an allOf if it is a REF
+         * and has_update is true */
     }
 
     switch (desc->repeat) {
@@ -795,6 +811,7 @@ t_iop_field_to_schema_object(const iop_struct_t *st, const iop_field_t *desc,
         }
       } break;
       case IOP_R_DEFVAL:
+        has_update = true;
         schema->defval = t_get_iop_field_defval(desc);
         break;
       default:
@@ -803,12 +820,27 @@ t_iop_field_to_schema_object(const iop_struct_t *st, const iop_field_t *desc,
 
     get_field_help(attrs, &help, &is_v2);
     if (help) {
+        has_update = true;
         schema->description = t_iop_help_to_string(help, false);
         if (is_v2) {
             schema->example = help->example;
         }
     }
 
+    if (has_update && schema->type == TYPE_REF) {
+        /* We cannot specify any fields with the REF type... so
+         * a allOf must be used to split the ref from the details */
+        schema_object_t *ref;
+
+        t_qv_init(&schema->all_of, 1);
+        ref = t_new(schema_object_t, 1);
+        ref->type = TYPE_REF;
+        ref->name = schema->name;
+        qv_append(&schema->all_of, ref);
+        schema->type = TYPE_NONE;
+        schema->name = LSTR_NULL_V;
+    }
+
     return schema;
 }
 

test-data/openapi/dox.yml

@@ -297,7 +297,9 @@ components:
           minimum: -2147483648
           maximum: 2147483647
         b:
-          $ref: "#/components/schemas/tstiop_dox.MyStruct"
+          description: "local comment for MyIface.funA.in.b\n\ncomment for b of funA.in"
+          allOf:
+            - $ref: "#/components/schemas/tstiop_dox.MyStruct"
       example: "{\"aParam\":1,\"b\":{\"fieldA\":11,\"fieldB\":12,\"fieldC\":13}}"
     tstiop_dox.MyClass:
       type: object

test-data/openapi/struct_g.yml

@@ -70,7 +70,9 @@ components:
           type: string
           default: "fo\"o?cbar\u00e9\u00a9"
         k:
-          $ref: "#/components/schemas/tstiop.MyEnumA"
+          allOf:
+            - $ref: "#/components/schemas/tstiop.MyEnumA"
+          default: 2
         l:
           type: number
           format: double