如何在 Flutter 中对 JSON 数据进行文本搜索？

我正在开发一个应用程序，该应用程序需要从 firebase 存储中获取一些 JSON 数据，然后用户可以对其执行搜索。但是，我的搜索查询无法正常工作，并且在多次执行搜索时出现一个错误。

我首先将数据上传到 firebase 存储，然后提取它。搜索有时有效。我无法弄清楚代码有什么问题。

这是完整的代码

import 'dart:typed_data';
import 'package:flutter/material.dart';
import 'package:firebase_storage/firebase_storage.dart';
import 'dart:convert';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Contacts Demo',
      debugShowCheckedModeBanner: false,
      home: StorageUpload(),
    );
  }
}

class StorageUpload extends StatefulWidget {
  @override
  StorageUploadState createState() => new StorageUploadState();
}

class StorageUploadState extends State<StorageUpload> {
  var rows = [];
  String query = '';
  TextEditingController tc;

  @override
  void initState() {
    super.initState();
    tc = TextEditingController();
    rows = [
      {
        'contact_name': 'Test User 1',
        'contact_phone': '066 560 4900',
      },
      {
        'contact_name': 'Test User 2',
        'contact_phone': '066 560 7865',
      },
      {
        'contact_name': 'Test User 3',
        'contact_phone': '906 500 4334',
      }
    ];
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text(
          "Delivero Contacts",
          style: new TextStyle(
            color: Colors.white,
          ),
        ),
      ),
      body: Container(
        color: Colors.white,
        padding: EdgeInsets.all(10),
        child: Stack(
          children: [
            Column(
              children: [
                Padding(
                  padding: const EdgeInsets.all(10.0),
                  child: TextField(
                    controller: tc,
                    decoration: InputDecoration(hintText: 'Search...'),
                    onChanged: (v) {
                      setState(() {
                        query = v;
                      });
                    },
                  ),
                ),
                Container(
                  color: Colors.white,
                  child: ListView.builder(
                    shrinkWrap: true,
                    itemCount: rows.length,
                    itemBuilder: (con, ind) {
                      return query.isEmpty
                          ? ListTile(
                              title: Text(rows[ind]['contact_name']),
                              subtitle: Text(rows[ind]['contact_phone']),
                              onTap: () {
                                setState(() {
                                  tc.text = rows[ind]['contact_name'];
                                  query = rows[ind]['contact_name'];
                                });
                              },
                            )
                          : rows[ind]['contact_name']
                                      .toString()
                                      .toLowerCase()
                                      .contains(query.toLowerCase()) ||
                                  rows[ind]['contact_phone']
                                      .toString()
                                      .toLowerCase()
                                      .contains(query.toLowerCase())
                              ? ListTile(
                                  title: Text(rows[ind]['contact_name']),
                                  subtitle: Text(rows[ind]['contact_phone']),
                                  onTap: () {
                                    setState(() {
                                      tc.text = rows[ind]['contact_name'];
                                      query = rows[ind]['contact_name'];
                                    });
                                  },
                                )
                              : null;
                    },
                  ),
                ),
              ],
            ),
          ],
        ),
      ),
    );
  }
}

这是我收到的错误

════════ Exception caught by rendering library ═════════════════════════════════
The following assertion was thrown during performLayout():
'package:flutter/src/rendering/sliver_multi_box_adaptor.dart': Failed assertion: line 662 pos 16: 'indexOf(child) == index': is not true.


Either the assertion indicates an error in the framework itself, or we should provide substantially more information in this error message to help you determine and fix the underlying cause.
In either case, please report this assertion by filing a bug on GitHub:
  https://github.com/flutter/flutter/issues/new?template=BUG.md

The relevant error-causing widget was
    ListView 
lib/main.dart:104
When the exception was thrown, this was the stack
#2      RenderSliverMultiBoxAdaptor.debugAssertChildListIsNonEmptyAndContiguous.<anonymous closure> 
package:flutter/…/rendering/sliver_multi_box_adaptor.dart:662
#3      RenderSliverMultiBoxAdaptor.debugAssertChildListIsNonEmptyAndContiguous 
package:flutter/…/rendering/sliver_multi_box_adaptor.dart:666
#4      RenderSliverList.performLayout 
package:flutter/…/rendering/sliver_list.dart:282
#5      RenderObject.layout 
package:flutter/…/rendering/object.dart:1767
#6      RenderSliverEdgeInsetsPadding.performLayout 
package:flutter/…/rendering/sliver_padding.dart:135
...
The following RenderObject was being processed when the exception was fired: RenderSliverList#5c228 relayoutBoundary=up17 NEEDS-LAYOUT NEEDS-COMPOSITING-BITS-UPDATE
RenderObject: RenderSliverList#5c228 relayoutBoundary=up17 NEEDS-LAYOUT NEEDS-COMPOSITING-BITS-UPDATE
    needs compositing
    parentData: paintOffset=Offset(0.0, 0.0) (can use size)
    constraints: SliverConstraints(AxisDirection.down, GrowthDirection.forward, ScrollDirection.idle, scrollOffset: 0.0, remainingPaintExtent: Infinity, crossAxisExtent: 372.7, crossAxisDirection: AxisDirection.right, viewportMainAxisExtent: Infinity, remainingCacheExtent: Infinity, cacheOrigin: 0.0)
    geometry: SliverGeometry(scrollExtent: 224.0, paintExtent: 224.0, maxPaintExtent: 224.0, cacheExtent: 224.0)
        scrollExtent: 224.0
        paintExtent: 224.0
        maxPaintExtent: 224.0
        cacheExtent: 224.0
    currently live children: 0 to 3
    child with index 0: RenderIndexedSemantics#ea1e2 relayoutBoundary=up18
        needs compositing
        parentData: index=0; layoutOffset=0.0 (can use size)
        constraints: BoxConstraints(w=372.7, 0.0<=h<=Infinity)
        semantic boundary
        size: Size(372.7, 56.0)
        index: 0
        child: RenderRepaintBoundary#17c6b relayoutBoundary=up19
            needs compositing
            parentData: <none> (can use size)
            constraints: BoxConstraints(w=372.7, 0.0<=h<=Infinity)
            layer: OffsetLayer#34eb7
                engine layer: OffsetEngineLayer#a8a79
                offset: Offset(0.0, 0.0)
            size: Size(372.7, 56.0)
            metrics: 0.0% useful (1 bad vs 0 good)
            diagnosis: insufficient data to draw conclusion (less than five repaints)
            child: RenderSemanticsAnnotations#2ecd5 relayoutBoundary=up20
                parentData: <none> (can use size)
                constraints: BoxConstraints(w=372.7, 0.0<=h<=Infinity)
                size: Size(372.7, 56.0)
                child: RenderMouseRegion#9a9a8 relayoutBoundary=up21
                    parentData: <none> (can use size)
                    constraints: BoxConstraints(w=372.7, 0.0<=h<=Infinity)
                    size: Size(372.7, 56.0)
                    listeners: enter, exit
                    cursor: SystemMouseCursor(click)
    child with index 3: RenderIndexedSemantics#96641 relayoutBoundary=up18
        needs compositing
        parentData: index=3; layoutOffset=168.0 (can use size)
        constraints: BoxConstraints(w=372.7, 0.0<=h<=Infinity)
        semantic boundary
        size: Size(372.7, 56.0)
        index: 3
        child: RenderRepaintBoundary#13951 relayoutBoundary=up19
            needs compositing
            parentData: <none> (can use size)
            constraints: BoxConstraints(w=372.7, 0.0<=h<=Infinity)
            layer: OffsetLayer#768be
                engine layer: OffsetEngineLayer#51b91
                offset: Offset(0.0, 168.0)
            size: Size(372.7, 56.0)
            metrics: 0.0% useful (1 bad vs 0 good)
            diagnosis: insufficient data to draw conclusion (less than five repaints)
            child: RenderSemanticsAnnotations#77b2c relayoutBoundary=up20
                parentData: <none> (can use size)
                constraints: BoxConstraints(w=372.7, 0.0<=h<=Infinity)
                size: Size(372.7, 56.0)
                child: RenderMouseRegion#9ae66 relayoutBoundary=up21
                    parentData: <none> (can use size)
                    constraints: BoxConstraints(w=372.7, 0.0<=h<=Infinity)
                    size: Size(372.7, 56.0)
                    listeners: enter, exit
                    cursor: SystemMouseCursor(click)
════════════════════════════════════════════════════════════════════════════════

我是一个 Flutter 菜鸟。如何从 Firebase 存储中获取的数据对不同的 JSON 字段执行全文搜索？任何帮助都会很棒。谢谢你的时间！

我稍微改变了你的代码来制作一个工作示例。 我添加了一个结果列表对象，并将“query.isEmpty”检查移到了 ListView 之前：

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Contacts Demo',
      debugShowCheckedModeBanner: false,
      home: StorageUpload(),
    );
  }
}

class StorageUpload extends StatefulWidget {
  @override
  StorageUploadState createState() => new StorageUploadState();
}

class StorageUploadState extends State<StorageUpload> {
  List results = [];

  var rows = [];
  String query = '';
  TextEditingController tc;

  @override
  void initState() {
    super.initState();
    tc = TextEditingController();
    rows = [
      {
        'contact_name': 'Test User 1',
        'contact_phone': '066 560 4900',
      },
      {
        'contact_name': 'Test User 2',
        'contact_phone': '066 560 7865',
      },
      {
        'contact_name': 'Test User 3',
        'contact_phone': '906 500 4334',
      }
    ];
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text(
          "Delivero Contacts",
          style: new TextStyle(
            color: Colors.white,
          ),
        ),
      ),
      body: Container(
        color: Colors.white,
        padding: EdgeInsets.all(10),
        child: Stack(
          children: [
            Column(
              children: [
                Padding(
                  padding: const EdgeInsets.all(10.0),
                  child: TextField(
                    controller: tc,
                    decoration: InputDecoration(hintText: 'Search...'),
                    onChanged: (v) {
                      setState(() {
                        query = v;
                        setResults(query);
                      });
                    },
                  ),
                ),
                Container(
                  color: Colors.white,
                  child: query.isEmpty
                      ? ListView.builder(
                          shrinkWrap: true,
                          itemCount: rows.length,
                          itemBuilder: (con, ind) {
                            return ListTile(
                              title: Text(rows[ind]['contact_name']),
                              subtitle: Text(rows[ind]['contact_phone']),
                              onTap: () {
                                setState(() {
                                  tc.text = rows[ind]['contact_name'];
                                  query = rows[ind]['contact_name'];
                                  setResults(query);
                                });
                              },
                            );
                          },
                        )
                      : ListView.builder(
                          shrinkWrap: true,
                          itemCount: results.length,
                          itemBuilder: (con, ind) {
                            return ListTile(
                              title: Text(results[ind]['contact_name']),
                              subtitle: Text(results[ind]['contact_phone']),
                              onTap: () {
                                setState(() {
                                  tc.text = results[ind]['contact_name'];
                                  query = results[ind]['contact_name'];
                                  setResults(query);
                                });
                              },
                            );
                          },
                        ),
                ),
              ],
            ),
          ],
        ),
      ),
    );
  }

  void setResults(String query) {
    results = rows
        .where((elem) =>
            elem['contact_name']
                .toString()
                .toLowerCase()
                .contains(query.toLowerCase()) ||
            elem['contact_phone']
                .toString()
                .toLowerCase()
                .contains(query.toLowerCase()))
        .toList();
  }
}