C#•2y ago

❔ Removing JSON data from JSON File

Hey, I am attempting to remove JSON data from a text file if required (I'm using it as a local database) This was my attempt:

Database? db = JsonConvert.DeserializeObject<Database>(File.ReadAllText("Files\\Database.json"));
foreach (var pendingOrder in db.PendingOrders)
 {
   var orderIndex = Program.PendingOrders.FindIndex(o => o.CustomerInfo.UserId == pendingOrder.CustomerInfo.UserId && o.CustomerInfo.ChannelId == pendingOrder.CustomerInfo.ChannelId);
   if (orderIndex < 0)
   {
     db.PendingOrders.Remove(pendingOrder);
   }
 }

Database? db = JsonConvert.DeserializeObject<Database>(File.ReadAllText("Files\\Database.json"));
foreach (var pendingOrder in db.PendingOrders)
 {
   var orderIndex = Program.PendingOrders.FindIndex(o => o.CustomerInfo.UserId == pendingOrder.CustomerInfo.UserId && o.CustomerInfo.ChannelId == pendingOrder.CustomerInfo.ChannelId);
   if (orderIndex < 0)
   {
     db.PendingOrders.Remove(pendingOrder);
   }
 }

Obviously, this doesn't work and I receive this error

System.InvalidOperationException: 'Collection was modified; enumeration operation may not execute.'

System.InvalidOperationException: 'Collection was modified; enumeration operation may not execute.'

I know this is because I am directly modifying the collection by removing the pending order - so I am hopefully looking for a better way of doing this. Thanks a lot.

11 Replies

Owen•2y ago

Note: I am using Newtonsoft.Json

ero•2y ago

any reason why you're using newtonsoft? System.Text.Json is a lot faster (especially in .net 7)

Owen•2y ago

My whole codebase uses it and it was all I was familiar with. Am using .NET 6

ero•2y ago

yeah stj is still faster in net6

Owen•2y ago

I will likely look to convert in the future - but for now it's probably too much to change over Have quite a lot of JSON processing in this project

ero•2y ago

for (int i = db.PendingOrders.Count - 1; i >= 0; i--)
{
  var pendingOrder = db.PendingOrders[i];

  int oi =
    Program.PendingOrders
    .FindIndex(o =>
      o.CustomerInfo.UserId == pendingOrder.CustomerInfo.UserId
      && o.CustomerInfo.ChannelId == pendingOrder.CustomerInfo.ChannelId);

  if (oi == -1)
    db.PendingOrders.RemoveAt(i);
}

for (int i = db.PendingOrders.Count - 1; i >= 0; i--)
{
  var pendingOrder = db.PendingOrders[i];

  int oi =
    Program.PendingOrders
    .FindIndex(o =>
      o.CustomerInfo.UserId == pendingOrder.CustomerInfo.UserId
      && o.CustomerInfo.ChannelId == pendingOrder.CustomerInfo.ChannelId);

  if (oi == -1)
    db.PendingOrders.RemoveAt(i);
}

Owen•2y ago

Appreciate this, I will test this after dinner and report back here! Hey, so this is exactly how i've implemented this. Upon running the function, it seems to run successfully however the JSON file still retains the data.

Owen•2y ago

Owen•2y ago

This is right at the end of the void Resolved! Was fixed by changing the db.PendingOrders = null to a new List Thanks for your help

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ Removing JSON data from JSON File