Question

我遇到了sqlalchemy的问题，其中会话似乎成功提交，但数据没有出现在底层数据库表中。但是，在提交之前和之后打印已提交的项目时，数据会显示。基本上，我要做的是分配一个项目（要更新的行），然后更新数据库中的计算值。

任何提示都表示赞赏！如果下面的代码不是最干净的话，请提前道歉 - 我刚刚开始自学python。

query_od_matrix = session.query(dr.ODMatrix).order_by(dr.ODMatrix.distance)

def generate_bins(qry):
mx = session.query(sa.func.max(dr.ODMatrix.origin_stops_id)).scalar()
# Testing
# print mx

for o in range(1, mx+1): # o=origin, d=destination
    query = qry.filter(dr.ODMatrix.origin_stops_id == o)
    dest_id = []
    dest_dist = []

    for row in query:
        # Testing
        # print row.origin_stops_id, row.destination_stops_id, row.distance
        dest_id.append(row.destination_stops_id)
        dest_dist.append(row.distance)

    # Testing
    # print dest_id, dest_dist
    no_items = len(dest_id)

    for d in range(0, no_items):
        # Testing
        # print d, dest_id[d], dest_dist[d]

        if d == 0: # First item
            lower = 0
            upper = 0.5 * (float(dest_dist[d]) +  float(dest_dist[d+1]))
        elif d == no_items-1: # Last item
            lower = 0.5 * (float(dest_dist[d]) +  float(dest_dist[d-1]))
            upper = None
        else:
            lower = 0.5 * (float(dest_dist[d]) +  float(dest_dist[d-1]))
            upper = 0.5 * (float(dest_dist[d]) +  float(dest_dist[d+1]))

        item = dr.ODMatrix(origin_stops_id=o, destination_stops_id=dest_id[d])
        # Testing
        # print d, dest_id[d], lower, upper
        # print dest_id[d], item.destination_stops_id
        item.bin_from = lower
        item.bin_to = upper
        # Testing
        # session.dirty
        # print item.origin_stops_id, item.destination_stops_id, item.bin_from, item.bin_to
        session.commit()
        # session.flush()
        # Testing
        # session.dirty
        # print item.origin_stops_id, item.destination_stops_id, item.bin_from, item.bin_to

Answer 1

您需要在提交之前将项目添加到会话

item = dr.ODMatrix(origin_stops_id=o, destination_stops_id=dest_id[d])
item.bin_from = lower
item.bin_to = upper
session.add(item)
session.commit()

SQLAlchemy：Session成功提交/刷新，但数据确实出现在数据库中

1 个答案: