Thanks Mike, Ideally we'd prefer to find a solution via Graphene-SQLAlchemy. Unfortunately we don't have the luxury of creating our own query when interacting with Graphene-SQLAlchemy.
So the key question for us is, can you modify an existing sqlalchemy.orm.query.Query object to insert a "func.max(Data.value)" object into the select? This is what Graphene-SQLAlchemy is giving us. If this is possible, then the group_by part is easy. We have tested that frequently, the hard part is the modifying the original "select" object. 1. We have tried add_columns, but that adds in incompatible object type in the GraphQL results making it an unusable option. 2. We thought that modifying the select would be possible using data with "statement.froms" but can't figure out how to update the MetaData object in it If modifying the "select" after its creation is not possible, we need to start considering using a separate reporting table with hourly data. On Wednesday, April 12, 2023 at 3:12:46 PM UTC-7 Mike Bayer wrote: > > > On Wed, Apr 12, 2023, at 5:21 PM, Luis Del Rio IV wrote: > > I am currently using the following sqlalchemy code, > > _query = super().get_query(model, info, sort, **args) > query = _query.group_by( > func.date_format(DataModel.timestamp, "%Y-%m-%d %H") > ) > return query > > I am trying to aggregate the the max value of a field from DataModel.value > utilizing the group by clause. > > In simple sql, you would do the following. > > SELECT max(data.value) AS data_value > from data > GROUP BY date_format(data.timestamp, "%Y-%m-%d %H") > > What would the proper way to express this? The various methods I have > tried somehow overwrite the original query and do not map to our attributes. > > > using legacy query style: > > q1 = session.query(func.max(Data.value)).group_by( > func.date_format(Data.timestamp, "%Y-%m-%d %H") > ) > > > using 2.0 style select(), replace "session.query" with "select": > > s1 = select(func.max(Data.value)).group_by( > func.date_format(Data.timestamp, "%Y-%m-%d %H") > ) > > POC script is at the bottom of this email. > > > > I have some additional context on the issue > > 1. We are using the graphene-sqlalchemy package. > 2. When you do a GraphQL web api query, the package creates a > sqlalchemy.orm.query.Query > object. > 3. We want to modify this standard query that the package creates so > that we can do the group_by action to help us get the maximum time series > value for every hour because this is not possible using GraphQL. > 4. Talking to the graphene-sqlalchemy team they told us the best place > to do the modification to the standardized query is in the get_query > method > (line 67) in this file: https://github.com/graphql- > python/graphene-sqlalchemy/blob/master/graphene_sqlalchemy/fields.py > > <https://github.com/graphql-python/graphene-sqlalchemy/blob/master/graphene_sqlalchemy/fields.py> > 5. The standardized query we need to modify translates to this SQL > statement: > > SELECT sy_data.oid_id, sy_data.rrd_timestamp, sy_data.cabinet_id, sy_data > .customer_id, sy_data.value, sy_data.active_flag, sy_data.timestamp > FROM sy_data > WHERE sy_data.rrd_timestamp >= %(rrd_timestamp_1)s AND > sy_data.rrd_timestamp <= %(rrd_timestamp_2)s AND (sy_data.oid_id = > %(oid_id_1)s OR sy_data.oid_id = %(o > id_id_2)s) ORDER BY sy_data.oid_id ASC, sy_data.rrd_timestamp ASC > > Therefore we need to find a way to insert a func.max for the values in the > first part of the SELECT statement, (before the FROM). It is easy for us to > apend the group_by like this. > > > if you have a Query which renders the above SQL, you can add group_by() to > it in place. but if these queries are being translated into GraphQL, and > GraphQL does not have any concept of GROUP BY, then it wont work, what you > want to do would not be possible unless a GraphQL query exists that does > what you need. > > > query.group_by( > func.date_format(DataModel.timestamp, "%Y-%m-%d %H") > ) > > The big issue for us is to figure out how to insert the func.max > > > see func at > https://docs.sqlalchemy.org/en/20/core/sqlelement.html#sqlalchemy.sql.expression.func > > > from sqlalchemy import Column > from sqlalchemy import DateTime > from sqlalchemy import func > from sqlalchemy import Integer > from sqlalchemy import select > from sqlalchemy.orm import declarative_base > from sqlalchemy.orm import Session > > Base = declarative_base() > > > class Data(Base): > __tablename__ = "data" > > id = Column(Integer, primary_key=True) > value = Column(Integer) > timestamp = Column(DateTime) > > > s = Session() > > q1 = s.query(func.max(Data.value)).group_by( > func.date_format(Data.timestamp, "%Y-%m-%d %H") > ) > > print(q1) > > s1 = select(func.max(Data.value)).group_by( > func.date_format(Data.timestamp, "%Y-%m-%d %H") > ) > > print(s1) > > -- SQLAlchemy - The Python SQL Toolkit and Object Relational Mapper http://www.sqlalchemy.org/ To post example code, please provide an MCVE: Minimal, Complete, and Verifiable Example. 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