Question

我有一个看起来像这样的JSON对象：

{
    name: 'test',
    details: {
        description: 'This is the long description',
        shortDescription: 'This is the short description (ironically longer than the description!)'
    }
}

显然，真实对象比这个例子复杂得多，但我省略了细节，因为它们只会使问题复杂化。所以，有了这个对象，我有一个试图获取属性值的函数，它看起来像这样：

// Private function for matching fields
var _matchField = function (item, filter) {

    // Our variables
    var text = item[filter.field],
        values = filter.expression.split(',');

    // If we have any text
    if (text) {

        // Loop through our values
        angular.forEach(values, function (value) {

            console.log(text);
            console.log(value);

            // See if we have a match
            if (text.toLowerCase().indexOf(value.toLowerCase()) > -1) {

                // We have found a match
                return true;
            }
        });
    }

    // We have found no matches
    return false;
}

问题在于：

var text = item[filter.field],

如果该属性只是名称，那么 item ['name'] 将适用于上述对象。但如果我想得到描述; item ['details.descrption'] 不起作用。所以我需要一个允许我指定属性名称的函数，它将找到属性并返回其值。但在我尝试编写之前，我希望可能有一个人遇到的简单解决方案。

Answer 1

您可以拆分对象的引用，并使用函数获取正确的嵌套对象/值。

function getValue(o, p) {
    if (typeof p === 'string') {
        p = p.split('.')
    }
    return p.length ? getValue(o[p.shift()], p) : o;
}

var item = { name: 'test', details: { description: 'This is the long description', shortDescription: 'This is the short description (ironically longer than the description!)' } };

document.write(getValue(item, 'details.description'));

Answer 2

您可以为此

编写自定义函数

function getProperty(json, field) {

   if (json == null || field == null) {
       return null;
   }

   var value = json;
   var fields = field.split(".");
   for (var i = 0; i < fields.length; i++) {

       value = value[fields[i]];

       if (value == null) {
           return null;
       }
   }

   return value;
}

检查此plnkr示例https://plnkr.co/edit/8Ayd9wnh1rJh1ycx5R1f?p=preview

Answer 3

我通过创建这个函数来解决这个问题：

// Private function to get the value of the property
var _getPropertyValue = function (object, notation) {

    // Get all the properties
    var properties = notation.split('.');

    // If we only have one property
    if (properties.length === 1) {

        // Return our value
        return object[properties];
    }

    // Loop through our properties
    for (var property in object) {

        // Make sure we are a property
        if (object.hasOwnProperty(property)) {

            // If we our property name is the same as our first property
            if (property === properties[0]) {

                // Remove the first item from our properties
                properties.splice(0, 1);

                // Create our new dot notation
                var dotNotation = properties.join('.');

                // Find the value of the new dot notation
                return _getPropertyValue(object[property], dotNotation);
            }
        }
    }
};

JavaScript在JSON对象中查找属性

3 个答案: