1

I started creating a flask application as I will be needing to do some visualization of some data that was recently transferred to a local postgresql database.

I have a lot of tables (33) which all have the same kind of content as currently just works as containers for different types of data (They contain a JSON object that's different in each of the tables though).

The tables are named "Table_#" (where # symbolizes a number among a defined subset of numbers).

models.py

I have created the following model:

from sqlalchemy import BigInteger, Column, JSON, Text
from app import db

class Table_1(db.Model):
    __tablename__ = 'table_1'

    id = db.Column(BigInteger, primary_key=True)
    did = db.Column(Text)
    timestamp = db.Column(BigInteger)
    data = db.Column(JSON)
    db_timestamp = db.Column(BigInteger)

    def __repr__(self):
        return '<1_Data %r>' % (self.did)

to test if I can actually grab some data from my postgresql.

__init__.py

from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config.from_object('config')
db = SQLAlchemy(app)

from app import views, models

config.py

In my config.py I have the following:

SQLALCHEMY_DATABASE_URI = "postgresql://<username>:<password>@localhost:5432/backupdata" //Ofc <username> and <password> isn't my credentials..

In my terminal (Windows cmd) I've tried running the following:

>python
>>>from app import db, models
>>>row = models.Table_1.query.get(1)

But for some reason when I try to print my row nothing is output.

I was hoping someone could have an idea why that is?

Improve this question
4
  • Do you have a record in the table with a primary key of 1? Commented Dec 5, 2016 at 12:32
  • Does the above command get the id's of the rows? I thought it was like just get 1 row.. But if it's the ID of the row then that is my problem. How would I got about getting a "random" row or a random subset of rows? Commented Dec 5, 2016 at 14:42
  • 1
    get does a primary key lookup. Commented Dec 5, 2016 at 14:44
  • Then I am definitively using the wrong command. Thanks for informing me. I will get right on checking the documentation ;) Commented Dec 5, 2016 at 15:03

3 Answers 3

Reset to default
1

I updated my model a bit, to see that I actually got a specific row.

from sqlalchemy import BigInteger, Column, JSON, Text
from app import db

class Table_1(db.Model):
    __tablename__ = 'table_1'

    id = db.Column(BigInteger, primary_key=True)
    did = db.Column(Text)
    timestamp = db.Column(BigInteger)
    data = db.Column(JSON)
    db_timestamp = db.Column(BigInteger)

    def __repr__(self):
        return '<1_Data %r, %r>' % (self.did, self.id)

And then the following query made me aware that actually have a working connection to SQLAlchemy through my flask application.

row = models.Table_910.query.filter_by(did='357139052424715').first()

Knowing that I have one item with the above did I could get a single item:

<1_Data '357139052424715', 738390911>
Improve this answer
Sign up to request clarification or add additional context in comments.

Comments

0

As stated in your answer, you would need to use the firts() method. Another option would be to limit your query as follows:

Table.query.limit(1).all()

This way you don't need a filter and can just retrieve the first item in the query (which seems to be what you wanted to do originally with query.get(1)

See here for more info.

Improve this answer

Comments

0

This sloution is with postgres and Flask without SQLAlchemy

@app.route('/contextget', methods=['GET']) 
def contextget():
    sql_query ="""SELECT * FROM context"""
    out = cur.execute(sql_query)
    context_records = cur.fetchall() 
    ContextRootKeys = []
    outp ="Print each row and it's columns values"
    for row in context_records:
        ContextRootKeys.append(row[1])
    conn.commit()
    print(ContextRootKeys)
    return outp
Improve this answer

Comments

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.