SQLAlchemy query where a column contains a substring

Question

I’m constructing a query using SQLAlchemy and SQLite3 in which I’d like to select rows in which a String column contains a particular substring. What is the best way to accomplish this?

Asked By: Dave

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Source

Answer 1

Filter by db.table.column.like('%needle%'). There is also ilike for a case insensitive search.

For a fancier interface you can allow for the known “dir” wildcards.

if '*' in needle or '_' in needle: 
    looking_for = needle.replace('_', '__')
                        .replace('*', '%')
                        .replace('?', '_')
else:
    looking_for = '%{0}%'.format(needle)

result = db.table.filter(db.table.column.ilike(looking_for))

Notes:

The db.table.filter and db.table.column is for SQLSoup (SQLSoup is useful if the database was made by another application)
for SQLAlchemy Core it is select(column_list).where(table.c.column.ilike(expr)). This interface is the way to go when you want all the power from raw SQL without having to compose statements by hand using string interpolation (use it along SQLSoup for introspection, so you don’t need to declare tables)
for SQLAlchemy Declarative (the one used in Flask) it is Model.query.filter(Model.field.ilike(expr))

Answered By: Paulo Scardine

Answer 2

While table.c.column.like("%...%") should work, there is a more direct way to say what you want:

table.c.column.contains("needle")

This will usually generate the same SQL query but it is better to read for the uninitiated.
Note that contains does not seem to escape “_” and “%”.

Answered By: Bluehorn

Answer 3

You can filter using contains operator:

Model.query.filter(Model.columnName.contains('sub_string'))

To negate in, use not_ operator with it:

Model.query.filter(not_(Model.columnName.contains('sub_string')))

Answered By: kartheek

Answer 4

@app.route('/<var>', methods=['GET'])
def getdb(var):
    look_for = '%{0}%'.format(var)
    log1 = table.query.filter(table.col.like(look_for))

I’ve used SQLAlchemy and Flask (app.route on top is a decorator).
I used the get API to take in the variable that the user wishes to search for and I’m converting that variable to store it in another variable called look_for(since var cannot be used directly in the query) by using the format() and log1 stores the queried tuples.

Answered By: Sneha Ravichandran

Answer 5

Here is a way to di in the newest versions of sqlalchemy

query = select(table_name).where(table_name.column.contains("value_youre_searching_for"))
results = await db.execute(query)
data = results.scalars().all()

Answered By: DINA TAKLIT

SQLAlchemy query where a column contains a substring

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