json - Angular 2 Pipe - 无法读取未定义的属性“toString”

Question

我在 angular 2 中有一个搜索管道设置。当我在 angular beta 14 上时，搜索管道运行良好，现在我升级到 rc5，搜索管道坏了，我得到了错误。如果我从产品加载的 html 代码中删除管道。它是一个通用的搜索和过滤管道，应该在许多模块中使用。请帮助解决问题。

TypeError: Cannot read property 'toString' of undefined
at SearchPipe.compareWithAllFields (http://localhost:4200/main.bundle.js:72117:57)
at Array.filter (native)
at SearchPipe.transform 

搜索.pipe.ts

import { Pipe, PipeTransform } from '@angular/core';
import {isObject} from "rxjs/util/isObject";
import {isEmpty} from "rxjs/operator/isEmpty";
import {empty} from "rxjs/Observer";
@Pipe({
    name: 'search'
})
export class SearchPipe implements PipeTransform
{
    transform(input, [searchString]:Array<String>)
    {
        if (input == null) return input;
        return input.filter(this.compareWithAllFields, searchString);
    }

    compareWithAllFields(value, index)
    {
        var fields = Object.keys(value);
        for (let i = 0; i < fields.length; i++)
        {
            if (value[fields[i]] != null)
            {
                if (isObject(value[fields[i]]))
                {
                    var childFields = Object.keys(value[fields[i]]);
                    if (childFields.length > 0)
                    {
                        for (let j = 0; j < childFields.length; j++)
                        {
                            if ((value[fields[i]][childFields[j]] + "").indexOf(this.toString()) !== -1)
                            {
                                return true;
                            }
                        }
                    }
                }
                if ((value[fields[i]] + "").indexOf(this.toString()) !== -1)
                {
                    return true;
                }
            }
        }
        return false;
    }
}

列表-products.component.html

<div class="container">
    <div class="row">
        <div class="col-sm-3 form-group">
            <input placeholder="search product" class="form-control" type="text" #searchProduct (keyup)="0">
        </div>
        <div class="col-sm-3 col-sm-offset-6">
            <button [routerLink]="['/LoggedIn','Product','ProductAdd']" class="btn btn-lg btn-app">Add Product</button>
        </div>
    </div>
    <div class="row">
        <div class="col-sm-12">
            <h3>Products</h3>
            <table class="table table-striped table-bordered">
                <thead>
                <tr>
                    <th>Sr #</th>
                    <th>Name</th>
                    <th>Category</th>
                    <th>Barcode</th>
                    <th>Unit</th>
                    <th>Description</th>
                    <th>Quantity</th>
                    <th>Minimum Stock Level</th>
                    <th>Discount</th>
                    <th>Cost</th>
                    <th>Actions</th>
                </tr>
                </thead>
                <tbody>
                <tr *ngFor="let product of products | search:searchProduct.value;let serial = index">
                    <td>{{ serial+1 }}</td>
                    <td>{{ product.name}}</td>
                    <td>{{ product.productCategory.name}}</td>
                    <td>{{ product.barcode}}</td>
                    <td>{{ product.unit?.name}}</td>
                    <td>{{ product.description}}</td>
                    <td>{{ product.quantity}}</td>
                    <td>{{ product.minimumStockLevel}}</td>
                    <td>{{ product.discount}}</td>
                    <td>{{ product.cost}}</td>
                    <td>
                        <button class="btn btn-danger" (click)="delete(product)">Delete</button>
                        <button class="btn btn-default"
                                [routerLink]="['/LoggedIn','Product','ProductEdit',{id:product.id}]">Edit
                        </button>
                    </td>
                </tr>
                </tbody>
            </table>
        </div>
    </div>
</div>

Answer 1

@usmanwalana，PIPE API 自 RC3/4 以来发生了变化，它现在将第二个参数作为字符串而不是数组返回。

所以改变，

transform(input, [searchString]:Array<String>)

至

transform(input, searchString)

Answer 2

解决方案：更改transform(input, [searchString]:Array<String>)为transform(input, searchString)

Answer 3

我想你需要改变

return input.filter(this.compareWithAllFields, searchString);

至

return input.filter(this.compareWithAllFields.bind(this), searchString);