C# MongoDB Operations: Examples of Nesting, Arrays, etc.

1. A field is an array. If this record does not exist in the array, add a record to the array.

            FilterDefinitionBuilder<WorkflowDo> fd = Builders<WorkflowDo>.Filter;
            var f = fd.And(fd.Eq(x => x.Id, record.Id), fd.Not(fd.ElemMatch(x => x.Definition, x => x.Version == newVersionStr)));


            UpdateDefinitionBuilder<WorkflowDo> up = Builders<WorkflowDo>.Update;
            var p = up.Push(x => x.Definition, definition);
            var result = await collection.UpdateOneAsync(f, p);

First, set the matching condition to find the root record and check if this record already exists in the array.

            var f = fd.And(fd.Eq(x => x.Id, record.Id), fd.Not(fd.ElemMatch(x => x.Definition, x => x.Version == newVersionStr)));

Then, use Push to add a record to the array.

up.Push(x => x.Definition, definition);

This way, there is no need to query the database in advance.

Conditional update:

        public async Task<ServiceResult> SetStateAsync(ObjectId id, WorkflowInstanceStatus state)
        {
            var f = Builders<WorkflowInstanceDo>.Filter.Where(x => x.Id == id);
            UpdateDefinitionBuilder<WorkflowInstanceDo> up = Builders<WorkflowInstanceDo>.Update;

            var p = up.Set(x => x.Status, state);
            var collection = _mongodb.GetCollection<WorkflowInstanceDo>();

            var result = await collection.UpdateOneAsync(f, p);
            return R.UpdateSuccess();
        }