在Flutter中查询后如何更新Firestore文档 [英] How to update a Firestore document after querying in Flutter

问题描述

查询完要更新的文档后，我试图弄清楚如何更新文档.这是我想出的代码:

I am trying to figure out how to update my document after I query the one I want to update. Here is the code I came up with:

Firestore.instance.collection("Social_Posts").where(data["postTitle"], isEqualTo: "postTitle").where(data["postContent"], isEqualTo: "postContent")
                  .snapshots()
                  .listen((event) {print("hh");});

每当执行此查询以查找正确的文档时，我都想通过在其上添加数字来更新该文档.

Whenever I perform this query to find the correct document, I would like to update the document by adding a number to it.

推荐答案

可以从内部更新文档，最简单的方法肯定是使用documentID并增加值Firestore具有特殊属性， FieldValue.increment(1) .使用此功能，您可以轻松地增加字段.

It is possible to update the document from inside, The easier way to do that would definitely be to use the documentID and to increment the value Firestore has a special property, FieldValue.increment(1). Using this you can easily increment a field.

假设您要在文档中增加1的字段是"numberField".

Lets say the field in the document you want to increment by 1, is "numberField".

使用异步/等待样式的更新代码:

onTap: () async {

              setState(() {
                _title = data["postTitle"];
                _content= data["postContent"];
              });
            
              print(_title);
              print(_content);

              QuerySnaphot snapshot = await Firestore.instance.collection("Social_Posts")
                  .where("postTitle" , isEqualTo: _title)
                  .where("postContent", isEqualTo: _content)
                  .getDocuments();

        if(snapshot.documents.isNotEmpty)
        {
            snapshot.documents.forEach((doc){
                doc.reference.updateData({"views" : FieldValue.increment(1),});
            });

        }
}
             

numberField将增加，而无需进行额外的调用来知道当前值.

The numberField will be incremented without needing to make an extra call to know the present value.

您在 .where()方法

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