(feat): Unpack extensions into complex function types #8

The more in-depth we use extensions, the more likely is is that we need custom extensions. New `UnpackExtensions` function in the high package makes this easy. Low level models have been updated to support feature fully and docs added in README and examples as well.

Signed-off-by: Dave Shanley <dave@quobix.com>

datamodel/high/shared_test.go

@@ -6,6 +6,7 @@ package high
 import (
     "github.com/pb33f/libopenapi/datamodel/low"
     "github.com/stretchr/testify/assert"
+    "gopkg.in/yaml.v3"
     "testing"
 )
 
@@ -18,4 +19,112 @@ func TestExtractExtensions(t *testing.T) {
     }
     ext := ExtractExtensions(n)
     assert.Equal(t, "new cowboy in town", ext["pb33f"])
+}
+
+type textExtension struct {
+    Cowboy string
+    Power  int
+}
+
+type parent struct {
+    low *child
+}
+
+func (p *parent) GoLow() *child {
+    return p.low
+}
+
+type child struct {
+    Extensions map[low.KeyReference[string]]low.ValueReference[any]
+}
+
+func (c *child) GetExtensions() map[low.KeyReference[string]]low.ValueReference[any] {
+    return c.Extensions
+}
+
+func TestUnpackExtensions(t *testing.T) {
+
+    var resultA, resultB yaml.Node
+
+    ymlA := `
+cowboy: buckaroo
+power: 100`
+
+    ymlB := `
+cowboy: frogman
+power: 2`
+
+    err := yaml.Unmarshal([]byte(ymlA), &resultA)
+    assert.NoError(t, err)
+    err = yaml.Unmarshal([]byte(ymlB), &resultB)
+    assert.NoError(t, err)
+
+    n := make(map[low.KeyReference[string]]low.ValueReference[any])
+    n[low.KeyReference[string]{
+        Value: "x-rancher-a",
+    }] = low.ValueReference[any]{
+        ValueNode: resultA.Content[0],
+    }
+
+    n[low.KeyReference[string]{
+        Value: "x-rancher-b",
+    }] = low.ValueReference[any]{
+        ValueNode: resultB.Content[0],
+    }
+
+    c := new(child)
+    c.Extensions = n
+
+    p := new(parent)
+    p.low = c
+
+    res, err := UnpackExtensions[textExtension, *child](p)
+    assert.NoError(t, err)
+    assert.NotEmpty(t, res)
+    assert.Equal(t, "buckaroo", res["x-rancher-a"].Cowboy)
+    assert.Equal(t, 100, res["x-rancher-a"].Power)
+    assert.Equal(t, "frogman", res["x-rancher-b"].Cowboy)
+    assert.Equal(t, 2, res["x-rancher-b"].Power)
+}
+
+func TestUnpackExtensions_Fail(t *testing.T) {
+
+    var resultA, resultB yaml.Node
+
+    ymlA := `
+cowboy: buckaroo
+power: 100`
+
+    // this is incorrect types, unpacking will fail.
+    ymlB := `
+cowboy: 0
+power: hello`
+
+    err := yaml.Unmarshal([]byte(ymlA), &resultA)
+    assert.NoError(t, err)
+    err = yaml.Unmarshal([]byte(ymlB), &resultB)
+    assert.NoError(t, err)
+
+    n := make(map[low.KeyReference[string]]low.ValueReference[any])
+    n[low.KeyReference[string]{
+        Value: "x-rancher-a",
+    }] = low.ValueReference[any]{
+        ValueNode: resultA.Content[0],
+    }
+
+    n[low.KeyReference[string]{
+        Value: "x-rancher-b",
+    }] = low.ValueReference[any]{
+        ValueNode: resultB.Content[0],
+    }
+
+    c := new(child)
+    c.Extensions = n
+
+    p := new(parent)
+    p.low = c
+
+    res, er := UnpackExtensions[textExtension, *child](p)
+    assert.Error(t, er)
+    assert.Empty(t, res)
 }