So I have a model Item that has a huge postgresql JSON field called properties. Most of the time this field does not need to be queried on or changed, however we store price in this field.
I'm currently writing a script that updates this price, but there's only a few unique prices and thousands of Items so in order to save time I have a list of Items for each unique price and I'm attempting to do an update all:
Item.where(id: items).update_all("properties->>'price' = #{unique_price}")
But this gives me:
syntax error at or near "->>"
Is there a way to use update all to update a field in a postgres JSON field?
You need to use jsonb_set() function, here is an example:
Item.where(id: items).
update_all(
"properties = jsonb_set(properties, '{price}', to_json(#{unique_price}::int)::jsonb)"
)
This would preserve all values and update only one key.
Read documentation
You can also do this
Item.where(id: items).each do |item|
properties = item.properties
item.update(properties: properties.merge({
price: unique_price
}))
end
The keyword merge will override the value of the key provided with the new value ie unique_price
Merge documentation is here
What I came up with based on #Philidor's suggestion is very similar but with dynamic bindings:
assignment = ["field = jsonb_set(field, '{ name_of_the_key }', ?)", value.to_json]
scope.update_all(scope.model.sanitize_sql_for_assignment(assignment))
Related
I'm using Rails to search through a SQLite table (for other reasons I can't use the standard database-model system) using a SELECT query like so:
info = ActiveRecord::Base.connection.execute("SELECT * FROM #{form_name} WHERE EmailAddress = \"#{user_em}\";")
This returns the correct values, but for some reason the output is in duplicate, the difference being the 2nd set doesn't have column titles in the hash, instead going from 0-[num columns]. For example:
{"id"=>1, "Timestamp"=>"2/27/2017 14:26:03", "EmailAddress"=>"-snip-", 0=>1, 1=>"2/27/2017 14:26:03", 2=>"-snip-"}
(I'll note the obvious- there's only one row in the table with that information in it)
While it's not exactly a fatal problem, I'm interested as to why it's doing so and if it's possible to prevent it. Thanks!
This allows you to read the values both by column index or column name:
id = row[0]
timestamp = row["Timestamp"]
I have three tables in my database: values, keys, and sources. Both keys and sources have many values. sources has a datetime column called file_date. For each key, I have to select all values that have a source that is between a specific date range (usually within two years). Not all dates within that range have a source, and not all sources have a value. I need to create an array that contains all values from within that range.
I at first tried to simply query the entire sources array at once, like so:
Value.where(key: 1, source: sources_array)
However, since there are several values that are nil, it simply returned records that have a value at that date.
So now, I've created an array containing all of the sources between that date range. Days that don't have a source simply have nil. Then, for each key, I iterate through the sources array, returning the value that matches that foo and source. That is obviously not ideal, and it takes about 7 seconds for the page to load.
Here is that code:
sources.map do |source|
Value.where(source: source, key: key)
end
Any ideas?
You could also generate a single SQL query if you only need to retrieve the data and getting back arrays will suffice.
output = []
sources.each do |source|
output << "select * from values where (source like #{source} and key like #{key})"
end
result = ActiveRecord::Base.connection.execute(output.join(" union ")).to_a
The big issue with your .map is that it runs several queries, instead of one query with all the results you want. With each additional query, you add the overhead of sending the request to the database and receiving the response back. What you need to do is generate the query in a way that it returns all the results you may be looking for, and then dealing with any grouping or sorting application side.
You could try wrapping your queries in a single transaction:
ActiveRecord::Base.transaction do
sources.map do |source|
Value.where(source: source, key: key)
end
end
I'll need to refactor this like crazy, but I have something that has cut it down to 3 seconds:
source_ids = sources.map do |source|
if source
source.id
else
nil
end
end
values = Value.where(source: sources, key: key)
value_sources = values.pluck(:source_id)
value_decimals = values.pluck(:value_decimal)
source_ids.map do |id|
index = value_sources.index(id)
if index
value_decimals[index]
else
nil
end
end
Hopefully this is a little clearer. I'm sorry but I'm very new to coding in general. I have multiple tables that I have to query in succession in order to get to the correct array that I need. The following logic for the query is as follows:
this gives me an array based upon the store :id
store = Stores.find(params[:id])
this gives me another array based upon the param .location found in the table store where that value equals the row ID in the table Departments
department = Departments.find(store.location)
I need to preform one last query but in order to do so I need to figure out which day of the meeting is needed. In order to do this I have to create the parameter day_of_meeting found in the table Stores. I try to call it from the array above and create a new variable. In the Table Departments, I there are params such as day_1, day_2 and so on. I need to be able to call something like department.day_1 or department.day_2. Thus, I'm trying to actually create the variable by join the words "department.day_" to the variable store.day_of_meeting which would equal some integer, creating department.day_1...
which_day = ["department.day_", store.day_of_meeting].join("")
This query finds uses the value found from the variable department.day_1 to query table Meeting to find the values in the corresponding row.
meeting = Meeting.find(which_day)
Does this make my problem any clearer to understand?
findmethod can only accept parameters like Meeting.find(1) or Meeting.find("1-xx").
so, what you need is Meeting.find(department.send("day_" + store.day_of_meeting.to_s))
Hope to help!
I'm building a summary of data based on multiple entities - to keep things simple for eg. a list of categories and the number of items present in each category returned as json e.g.
{"report":["Fruit",35]}
#array = []
#active_rec = Category.all
#array = #active_rec.collect{ |u| [u.name, ?how to insert AR query result? }
How can I plug a value along with the name that is the result of another query eg. is it possible to perform a query inline on a current row ?
Thanks!
Made some assumptions about your date model:
Fruit.joins(:category).group('categories.id').select('categories.name, COUNT(fruits.id)')
Or (depending on how you want to handle the case of duplicate category names):
Fruit.joins(:category).group('categories.name').count('fruits.id')
Note the output will be in a different format depending on which of these you choose.
So I am pulling my hair over this issue / gotcha. Basically I used find_by_sql to fetch data from my database. I did this because the query has lots of columns and table joins and I think using ActiveRecord and associations will slow it down.
I managed to pull the data and now I wanted to modify returned values. I did this by looping through the result ,for example.
a = Project.find_by_sql("SELECT mycolumn, mycolumn2 FROM my_table").each do |project|
project['mycolumn'] = project['mycolumn'].split('_').first
end
What I found out is that project['mycolumn'] was not changed at all.
So my question:
Does find_by_sql return an array Hashes?
Is it possible to modify the value of one of the attributes of hash as stated above?
Here is the code : http://pastie.org/4213454 . If you can have a look at summarize_roles2() that's where the action is taking place.
Thank you. Im using Rails 2.1.1 and Ruby 1.8. I can't really upgrade because of legacy codes.
Just change the method above to access the values, print value of project and you can clearly check the object property.
The results will be returned as an array with columns requested encapsulated as attributes of the model you call this method from.If you call Product.find_by_sql then the results will be returned in a Product object with the attributes you specified in the SQL query.
If you call a complicated SQL query which spans multiple tables the columns specified by the SELECT will be attributes of the model, whether or not they are columns of the corresponding table.
Post.find_by_sql "SELECT p.title, c.author FROM posts p, comments c WHERE p.id = c.post_id"
> [#<Post:0x36bff9c #attributes={"title"=>"Ruby Meetup", "first_name"=>"Quentin"}>, ...]
Source: http://api.rubyonrails.org/v2.3.8/
Have you tried
a = Project.find_by_sql("SELECT mycolumn, mycolumn2 FROM my_table").each do |project|
project['mycolumn'] = project['mycolumn'].split('_').first
project.save
end