我正在开发Flutter应用。我们有一个PSQL数据库,后台有Node服务器。在Flutter应用程序上,我正在显示一些我成功从数据库中获取的几何图形。现在,在对几何图形(例如线)进行修改之后,我希望能够通过放置请求来更新数据库。
服务器的样子:
app.put('/api/shape/:id', async (req,res) =>{
let answer;
if( req.body.shape_type == "line"){
answer = await db.db.modify_line(req.params.id, req.body.info_shape);
}
res.send(answer);
});
并且db.js文件如下:
modify_line : async function(id_shape, info_shape){
console.log(info_shape);
const result = await send_query("UPDATE line SET line = $2 WHERE id_shape = $1", [id_shape, info_shape]);
return(result);
},
在Flutter应用程序上,我这样做:
_makeUpdateRequest() async {
var url = globals.URL + 'api/shape/' + globals.selectedShapeID.toString();
Map data;
if (globals.selectedType == globals.Type.line) {
String lseg = "(" + globals.pLines[globals.selectedLineIndex].p1.dx.toString() + "," +
globals.pLines[globals.selectedLineIndex].p1.dy.toString() + "," +
globals.pLines[globals.selectedLineIndex].p2.dx.toString() + "," +
globals.pLines[globals.selectedLineIndex].p2.dy.toString() + ")";
data = {
'shape_type': 'line',
'info_shape': {
'id_shape': globals.selectedShapeID.toString(),
'line': lseg,
}
};
}
http.Response response;
try {
//encode Map to JSON
print("encode Map to JSON");
var body = json.encode(data);
print(body);
response =
await http.put(url,
headers: {
"Content-Type": "application/json"
},
body: body
).catchError((error) => print(error.toString()));
} catch (e) {
print(e);
}
return response;
}
数据库“行”表在每一行上均包含“ shapeID”和“ lseg”信息。
当前尝试此代码时出现错误:
{ id_shape: '619',
line: '(19.5,100.6,20.5,50.9)' }
fail____error: invalid input syntax for type lseg: "{"id_shape":"619","line":"(-19.5,100.6,20.5,50.9)"}"
我应该如何塑造我的lseg json?谢谢
嗯,在我看来,您正在按照input_shape
将整个console.log
对象传递给SQL查询,该查询看起来像这样:
{
id_shape: '619',
line: '(19.5,100.6,20.5,50.9)'
}
显然,这对PostgreSQL无效。
我会说您的后端代码应该更像这样:
modify_line : async function(id_shape, info_shape){
console.log(info_shape);
const result = await send_query(
"UPDATE line SET line = $2 WHERE id_shape = $1",
// Reference "line" sub-object
[id_shape, info_shape.line],
);
return(result);
},
您还应注意行的Geometric types格式:
[((x1,y1),(x2,y2)]
((x1,y1),(x2,y2))
((x1,y1),(x2,y2)
x1,y1,x2,y2
我不能百分百确定您的格式(带括号的前后)是正确的。