Golang中WASM构建时如何使用可选参数

Golang中WASM构建时如何使用可选参数 我正在尝试将以下来自IndexedDB JavaScript API的代码转换为GO WASM：

request.onupgradeneeded = function(event) {
    var db = event.target.result;
    var objectStore = db.createObjectStore("employee", {keyPath: "id"});
    
    for (var i in employeeData) {
       objectStore.add(employeeData[i]);
    }
 }

因此，我编写了：

    var dbUpgrade js.Func
    var result, request js.Value

	dbUpgrade = js.FuncOf(func(this js.Value, args []js.Value) interface{} {
		defer dbUpgrade.Release()
		result = this.Get("result")

    	var objectStore = result.Call("createObjectStore", "employee")
		objectStore.Call("add", `{ id: "00-01", name: "Karam", age: 19, email: "kenny@planet.org" }`)

		window.Call("alert", "First record posted.")
		return nil
	})
	request.Set("onupgradeneeded", dbUpgrade)

但我遇到了以下运行时错误：

panic: JavaScript error: Failed to execute 'add' on 'IDBObjectStore': The object store uses out-of-line keys and has no key generator and the key parameter was not provided.

我理解原因是因为在 result.Call("createObjectStore", "employee" 处没有包含 {keyPath: "id"} 来匹配JavaScript的代码，但我尝试了以下方法，都没有成功：

// 1.
result.Call("createObjectStore", "employee", "{keyPath: `id`}")
// 2.
key, _ := json.Marshal(map[string]string{"keyPath": "id"})
result.Call("createObjectStore", "employee", key)
// 3. 
result.Call("createObjectStore", `"employee", "{keyPath: "id"}"`)

有什么想法可以解决这个问题吗？


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1 回复

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在Go WASM中传递JavaScript对象参数需要使用js.ValueOf将Go的map转换为JavaScript对象。以下是正确的实现方式：

var dbUpgrade js.Func
var result, request js.Value

dbUpgrade = js.FuncOf(func(this js.Value, args []js.Value) interface{} {
    defer dbUpgrade.Release()
    result = this.Get("result")

    // 创建JavaScript对象作为可选参数
    options := map[string]interface{}{
        "keyPath": "id",
    }
    jsOptions := js.ValueOf(options)

    // 传递JavaScript对象参数
    var objectStore = result.Call("createObjectStore", "employee", jsOptions)
    
    // 添加数据时需要提供键值
    employeeData := map[string]interface{}{
        "id":    "00-01",
        "name":  "Karam",
        "age":   19,
        "email": "kenny@planet.org",
    }
    jsEmployeeData := js.ValueOf(employeeData)
    objectStore.Call("add", jsEmployeeData)

    window.Call("alert", "First record posted.")
    return nil
})
request.Set("onupgradeneeded", dbUpgrade)

如果需要添加多个员工数据，可以使用循环：

employees := []map[string]interface{}{
    {"id": "00-01", "name": "Karam", "age": 19, "email": "kenny@planet.org"},
    {"id": "00-02", "name": "Alice", "age": 25, "email": "alice@example.com"},
}

for _, emp := range employees {
    jsEmp := js.ValueOf(emp)
    objectStore.Call("add", jsEmp)
}

对于更复杂的配置选项，比如包含autoIncrement：

options := map[string]interface{}{
    "keyPath": "id",
    "autoIncrement": false,
}
jsOptions := js.ValueOf(options)
var objectStore = result.Call("createObjectStore", "employee", jsOptions)

关键点是使用js.ValueOf()将Go的map转换为JavaScript对象，这样就能正确传递可选参数给JavaScript API。

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