'parsing airtable json to flutter podo

I'm new in flutter and I have issue with parsing JSON on HTTP response.

I'm using Airtable backend, to store information about posts. These always contain images, and sometimes attachments - PDFs.

I built PODO, like this:

class Post {

String recordid;
String timecreated;
String title;
String content;
String imgurl;
List<Pdf>? pdf;

  Post({
    required this.recordid,
    required this.timecreated,
    required this.title,
    required this.content,
    required this.imgurl,
    required this.pdf
  });

  factory Post.fromJson(Map<String, dynamic> json) {
    return Post(
        // fields: Fields.fromJson(json['fields']),
      recordid: json['id'] as String,
      timecreated: json['createdTime'] as String,
        title: json['fields']['field1'] as String,
        content: json['fields']['field2'] as String,
        imgurl: json['fields']['IMG'][0]['url'] as String,
        pdf: json['fields']['PDF'] == null ? null : List<Map<String, dynamic>>.from(json['fields']['PDF']).map((dynamic value) => Pdf.fromJson(value)).toList()
    );
  }

Map<String, dynamic> toJson() => {
  "recordid": recordid,
  "timecreated": timecreated,
  "title": title,
  "content": content,
  "imgurl": imgurl,
  "pdf": pdf
  // "fields": List<dynamic>.from(fields.map((x) => x.toJson())),
};
}

class Pdf {

  Pdf({
    required this.url,
    required this.filename
  });

  Pdf.fromJson(Map<String, dynamic> json) :
        url = json['url'],
        filename = json['filename'];

  final String? url;
  final String? filename;
}

I'm not getting any errors, but when I'm trying to use PDF URL in UI, eg. in Text:

ListTile(title: Text(post.pdf.url)),

I'm getting error:

The property 'url' can't be unconditionally accessed because the receiver can be 'null'.

I'm aiming to create a button on a page, that is clickable when PDF URL exists. When it exists, button navigates to PDF view that use PDF URL to get and display PDF.

Any ideas?

Solution 1:^[1]

The pdf attribute is nullable, hence it cannot be accessed unconditionally. This is assuming you somehow have the pdf not as a list, otherwise you would need to index your list, your code is incomplete. You could try to do something like this:

  if (post.pdf != null) {
      //wrap it with a button or whatever
      return ListTile(title: Text(post.pdf!.url));
  }
  else {
      return Text('no pdf');
  }

Solution 2:^[2]

Well, sth seems to work, but still cannot parse pdf URL.

I'm getting Text "sth is there" when post.pdf != null and it works, but when I'm changing to get value from model using post.pdf!.url I'm getting same error:

Try correcting the name to the name of an existing getter, or defining a getter or field named 'url'. child:Text(post.pdf!.url));

Here's piece of code:

LayoutBuilder(builder: (context, constraints) {
                if(post.pdf != null){
                  return ElevatedButton(onPressed: () => Navigator.of(context).push(
                      MaterialPageRoute(builder: (context) => PDFview(pdf: [])
                      )),
                      child:Text(post.pdf!.url));
                }else{
                  return ElevatedButton(onPressed: null,
                      child:Text("no PDF"));
                }
              }
              )

Solution 3:^[3]

A fix in PODO worked for me.

Here's solution for my problem :)

pdf: json['fields']['PDF'] == null ? null : json['fields']['PDF'][0]['url'] as String,

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution	Source
Solution 1	void void
Solution 2	dave
Solution 3	dave

'parsing airtable json to flutter podo

Solution 1:[1]

Solution 2:[2]

Solution 3:[3]

Sources

Related Questions

Solution 1:^[1]

Solution 2:^[2]

Solution 3:^[3]