Fix rendering for default/example values of 0.

src/core/components/parameter-row.jsx

@@ -119,17 +119,21 @@ export default class ParameterRow extends Component {
       //// Find an initial value
 
       if (specSelectors.isSwagger2()) {
-        initialValue = paramWithMeta.get("x-example")
-          || paramWithMeta.getIn(["schema", "example"])
-          || (schema && schema.getIn(["default"]))
+        initialValue = [
+          paramWithMeta.get("x-example"),
+          paramWithMeta.getIn(["schema", "example"]),
+          schema.getIn(["default"])
+        ].find(v => v !== undefined)
       } else if (specSelectors.isOAS3()) {
         const currentExampleKey = oas3Selectors.activeExamplesMember(...pathMethod, "parameters", this.getParamKey())
-        initialValue = paramWithMeta.getIn(["examples", currentExampleKey, "value"])
-          || paramWithMeta.getIn(["content", parameterMediaType, "example"])
-          || paramWithMeta.get("example")
-          || (schema && schema.get("example"))
-          || (schema && schema.get("default"))
-          || paramWithMeta.get("default") // ensures support for `parameterMacro`
+        initialValue = [
+          paramWithMeta.getIn(["examples", currentExampleKey, "value"]),
+          paramWithMeta.getIn(["content", parameterMediaType, "example"]),
+          paramWithMeta.get("example"),
+          schema.get("example"),
+          schema.get("default"),
+          paramWithMeta.get("default") // ensures support for `parameterMacro`
+        ].find(v => v !== undefined)
       }
 
       //// Process the initial value

test/mocha/bugs/5573-zero-default-example-values.jsx

@@ -0,0 +1,145 @@
+/* eslint-env mocha */
+import React from "react"
+import { List, fromJS } from "immutable"
+import expect, { createSpy } from "expect"
+import { render } from "enzyme"
+import ParameterRow from "components/parameter-row"
+
+describe("bug #5573: zero default and example values", function(){
+  it("should apply a Swagger 2.0 default value of zero", function(){
+    const paramValue = fromJS({
+      description: "a pet",
+      type: "integer",
+      default: 0
+    })
+
+    let props = {
+      getComponent: ()=> "div",
+      specSelectors: {
+        security(){},
+        parameterWithMetaByIdentity(){ return paramValue },
+        isOAS3(){ return false },
+        isSwagger2(){ return true }
+      },
+      fn: {},
+      operation: {get: ()=>{}},
+      onChange: createSpy(),
+      param: paramValue,
+      rawParam: paramValue,
+      onChangeConsumes: () => {},
+      pathMethod: [],
+      getConfigs: () => { return {} },
+      specPath: List([])
+    }
+
+    render(<ParameterRow {...props}/>)
+
+    expect(props.onChange).toHaveBeenCalled()
+    expect(props.onChange).toHaveBeenCalledWith(paramValue, "0", false)
+  })
+  it("should apply a Swagger 2.0 example value of zero", function() {
+    const paramValue = fromJS({
+      description: "a pet",
+      type: "integer",
+      schema: {
+        example: 0
+      }
+    })
+
+    let props = {
+      getComponent: ()=> "div",
+      specSelectors: {
+        security(){},
+        parameterWithMetaByIdentity(){ return paramValue },
+        isOAS3(){ return false },
+        isSwagger2(){ return true }
+      },
+      fn: {},
+      operation: {get: ()=>{}},
+      onChange: createSpy(),
+      param: paramValue,
+      rawParam: paramValue,
+      onChangeConsumes: () => {},
+      pathMethod: [],
+      getConfigs: () => { return {} },
+      specPath: List([])
+    }
+
+    render(<ParameterRow {...props}/>)
+
+    expect(props.onChange).toHaveBeenCalled()
+    expect(props.onChange).toHaveBeenCalledWith(paramValue, "0", false)
+  })
+  it("should apply an OpenAPI 3.0 default value of zero", function(){
+    const paramValue = fromJS({
+      description: "a pet",
+      schema: {
+        type: "integer",
+        default: 0
+      }
+    })
+
+    let props = {
+      getComponent: ()=> "div",
+      specSelectors: {
+        security(){},
+        parameterWithMetaByIdentity(){ return paramValue },
+        isOAS3(){ return true },
+        isSwagger2() { return false }
+      },
+      oas3Selectors: {
+        activeExamplesMember: () => null
+      },
+      fn: {},
+      operation: {get: ()=>{}},
+      onChange: createSpy(),
+      param: paramValue,
+      rawParam: paramValue,
+      onChangeConsumes: () => {},
+      pathMethod: [],
+      getConfigs: () => { return {} },
+      specPath: List([])
+    }
+
+    render(<ParameterRow {...props}/>)
+
+    expect(props.onChange).toHaveBeenCalled()
+    expect(props.onChange).toHaveBeenCalledWith(paramValue, "0", false)
+  })
+  it("should apply an OpenAPI 3.0 example value of zero", function() {
+    const paramValue = fromJS({
+      description: "a pet",
+      schema: {
+        type: "integer",
+        example: 0
+      }
+    })
+
+    let props = {
+      getComponent: ()=> "div",
+      specSelectors: {
+        security(){},
+        parameterWithMetaByIdentity(){ return paramValue },
+        isOAS3(){ return true },
+        isSwagger2() { return false }
+      },
+      oas3Selectors: {
+        activeExamplesMember: () => null
+      },
+      fn: {},
+      operation: {get: ()=>{}},
+      onChange: createSpy(),
+      param: paramValue,
+      rawParam: paramValue,
+      onChangeConsumes: () => {},
+      pathMethod: [],
+      getConfigs: () => { return {} },
+      specPath: List([])
+    }
+
+    render(<ParameterRow {...props}/>)
+
+    expect(props.onChange).toHaveBeenCalled()
+    expect(props.onChange).toHaveBeenCalledWith(paramValue, "0", false)
+  })
+})