如何对Flutter中的JSON数据进行文本搜索？

Question

I am working on an application which requires to fetch some JSON data from firebase storage and then a user can perform a search over it. But, my search query isn't working properly and I get one error when I perform the search multiple times.

I have first uploaded the data to firebase storage and then fetched it. The search is working sometimes only. I cannot figure out what is wrong with the code.

Here is the complete code

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;
                    },
                  ),
                ),
              ],
            ),
          ],
        ),
      ),
    );
  }
}

Here is the error I am getting

════════ 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)
════════════════════════════════════════════════════════════════════════════════

I am a Flutter noob. How can I perform a full-text search over different JSON field from the data fetched from firebase storage? Any help would be amazing. Thanks for your time!

Answer 1

import 'dart:async';

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<Map<String,dynamic>> original=[],duplicate=[];
  String query = '';
  TextEditingController tc;
  StreamController<List<Map<String,dynamic>>> controller = StreamController<List<Map<String,dynamic>>>();

  @override
  void initState() {
    super.initState();
    tc = TextEditingController();
    original = [
      {
        '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',
      }
    ];
    duplicate.addAll(original);
    controller.sink.add(duplicate);
  }

  @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) {
                      if(v.isEmpty){
                        duplicate = original;
                        controller.sink.add(duplicate);
                        return;
                      }

                      //If your data is a Map object you can use toString()
                      //and avoid checking both fields
                      duplicate = original.where((m)=>
                                                 m['contact_name'].toString().toLowerCase().contains(v.toLowerCase())||
                                                m['contact_phone'].toString().toLowerCase().contains(v.toLowerCase())).toList();
                      controller.sink.add(duplicate);
                    },
                  ),
                ),
                Container(
                  color: Colors.white,
                  child: StreamBuilder<Object>(
                    stream: controller.stream,
                    builder: (context, snapshot) {
                      return ListView.builder(
                        shrinkWrap: true,
                        itemCount: duplicate.length,
                        itemBuilder: (con, ind) {
                          return query.isEmpty
                              ? ListTile(
                                  title: Text(duplicate[ind]['contact_name']),
                                  subtitle: Text(duplicate[ind]['contact_phone']),
                                  onTap: () {
                                    setState(() {
                                      tc.text = duplicate[ind]['contact_name'];
                                      query = duplicate[ind]['contact_name'];
                                    });
                                  },
                                )
                              : duplicate[ind]['contact_name']
                                          .toString()
                                          .toLowerCase()
                                          .contains(query) ||
                                      duplicate[ind]['contact_phone']
                                          .toString()
                                          .toLowerCase()
                                          .contains(query)
                                  ? ListTile(
                                      title: Text(duplicate[ind]['contact_name']),
                                      subtitle: Text(duplicate[ind]['contact_phone']),
                                      onTap: () {
                                        setState(() {
                                          tc.text = duplicate[ind]['contact_name'];
                                          query = duplicate[ind]['contact_name'];
                                        });
                                      },
                                    ):null;
                        },
                      );
                    }
                  ),
                ),
              ],
            ),
          ],
        ),
      ),
    );
  }
  @override
  void dispose(){
    controller?.close();
    super.dispose();
  }
}

Answer 2

I slightly changed your code to make a working sample. I added a results List object and I moved the "query.isEmpty" check before the ListView:

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();
  }
}