I am completely new to Rails and MongoDB. I am using Rails-3 and MongoDB with MongoMapper to create a small application which stores some data and returns the data in json format. The client expects the json in a particular format. But I am not able to create the same format in the saved document.
Reqd Format:
{"Name":"ABC","max":{"key":"KEY-1","value":"100"},"min":{"key":"KEY-2","value":"0"}}
Parent Doc
class Story
include MongoMapper::Document
key :item, String
key :max,
key :min,
end
What I want is to create a document {"key":"KEY-1","value":"100"} first and then map that document to the parent document's max key and similarly another document to the min key.
I tried many ways, but I am not able to make it work.
Also,
The I want to remove the field id (object id) from the response JSON while returning to the client.
Sample JSON:
{"id":"51e64bce44ae8bf1fea3f78f","text":"Text 1","value":"Value 1"}
How can i do that?
Update
Answering one of my own question : "Removing the non-required fields from the json response"
It can be done by defining the as_json method inside the Model class. This will add only the fields 'key' and 'value' to the generated json.
def as_json(options={}){
:key =>self.key,
:value => self.value
}
Answering to my own question:
I searched around and couldn't find any satisfactory answer for my question.
On a temporary basis, I had created hash for the inner class and was assigning the value. This was a temporary solution which is little dirty.
I had posted the same question to a mongomapper group and got the answer. Sharing that answer here..
Assume that I have a model called Inner and another called Outer
one :max, :class_name => Inner
This will embed the Inner class object to the max attribute of the Outer class
Related
I recently started experimenting with the REST API for SharePoint 2013 Foundation and I am trying to return all entries in a list. My GET request returns the data I am looking for, but the IDs used to identify the columns in the list are not helpful for identifying what the information is (see images below). The column IDs between 'Title' and 'ID', in the second image, are a jumble of characters.
SharePoint List View
Response Data
Is there any way to configure the list to use the column names as IDs? Also, is there some significance to the characters currently used as IDs?
You will need to make a second request to get a listing of columns that includes the InternalName and the Title which is what you are trying to reference:
You can use this REST call:
_api/web/lists/GetByTitle('Project Details')/fields
or you can use CSOM:
using (ClientContext context = new ClientContext(url))
{
List list = context.Web.Lists.GetByTitle("Project Details");
context.Load(list, l => l.Fields);
context.ExecuteQuery();
foreach(Field field in list.Fields)
{
Console.WriteLine(field.Title);
Console.WriteLine(field.InternalName);
}
}
SharePoint automatically generates the InternalName and it is a read-only field, at least using REST. It'll be easier to get the Field Data to correlate the InternalName to the Title than changing the values.
The column you are referring to, between Title and Id, is the ID of the content type associated to the item. It is not a column ID.
The SharePoint REST API is OData compliant, so you can use the $select parameter to query for the neccesary fields.
http://server/site/_api/web/lists('guid')/items?$select=Column1,Column2
Please be aware though, lookup fields need to be expanded as well, otherwise you get only the Id of the lookup item.
http://server/site/_api/web/lists('guid')/items?$select=LookupColumn&$expand=LookupColumn/Title
This is a somewhat more complicated version of the question I asked previously.
Background:
So what I need is to display a list of articles. An article belongs to a media outlet. A media is located in a particular country and publishes articles in a particular language. So the data structure is as follows:
Article belongs to Media; Media has many Articles
Media belongs to a Country; Country has many Media
Media belongs to a Language; Language has many Media
Now, if I wanted to filter articles by media, I could use the following class method (I prefer class methods over scopes, because I am passing a parameter and am using a conditional statement inside the method):
def self.filter_by_media(parameter)
if parameter == "all"
all
else
where(media_id: parameter)
end
end
Question:
How to write a class method that would filter Articles based by properties of its associated model, the Media? For example, I want to get a list of articles published by media located a certain counrty or in several countries (there is also a default country when the user does not make any choice). Here’s what I tried:
# parameter can be either string 'default' or an array of id’s
def self.filter_by_country(parameter)
if parameter == "default"
joins(:media).where(media: [country_id: 1])
else
joins(:media).where(media: [country_id: parameter])
end
end
But that doesn’t work, and I am not conversant enough with SQL to figure out how to make this work. Could you please help?
Update:
I’m trying out #carlosramireziii's suggestion. I changed arrays into hashes (don't know what possessed me to use arrays in the first place), but I’m getting the following error in the Rails console (to avoid confusion, in my database, media is called agency):
def self.filter_by_country(parameter)
if parameter == "default"
joins(:agency).where(agency: {country_id: 1})
else
joins(:agency).where(agency: {country_id: parameter})
end
end
in Rails console:
> Article.filter_by_country('default')
=> Article Load (1.9ms) SELECT "articles".* FROM "articles" INNER JOIN "agencies" ON "agencies"."id" = "articles"."agency_id" WHERE "agency"."country_id" = 1
PG::UndefinedTable: ERROR: missing FROM-clause entry for table "agency"
LINE 1: ...ON "agencies"."id" = "articles"."agency_id" WHERE "agency"."...
^
: SELECT "articles".* FROM "articles" INNER JOIN "agencies" ON "agencies"."id" = "articles"."agency_id" WHERE "agency"."country_id" = 1
Update 2
My mistake in the Update section above is that I did not pluralize agency in the where clause. The part where(agency: {country_id: 1}) should have read where(agencies: {country_id: 1}). The pluralized word agencies here refers to the name of the table that is being joined.
You are very close, you just need to use a nested hash instead of an array.
Try this
def self.filter_by_country(parameter)
if parameter == "default"
joins(:media).where(media: { country_id: 1 })
else
joins(:media).where(media: { country_id: parameter })
end
end
First, some background:
I have a Company model, a Project model and a Task model. A Project belongs to a company and a Task belongs_to a Project.
The Project model holds several attributes: company_id, date. These attributes uniquely identify a project
I am letting the users create a task by API by POSTing to a URL that contains the details necessary to identify the Project. For example:
POST /projects/<comnpany_name>/<date>/tasks/
In order to make life easier for the users, in case there is no project with the given details, I'd like to create the project on the fly by the given details, and then to create the task and assign it to the project.
...And my problem is:
When there is a problem to create the project, let's say that the company name is not valid, what is the right way to return the error message and communicate to the user?
I'll explain what I mean: I added a create_by_name_and_company_name method to the Project:
def self.create_by_name_and_company_name(name, company_name)
if company = Company.find_by_name(company_name)
project = Project.create(company_id: company.id,
name: name)
else # cannot create this project, trying to communicate the error
project = Project.new(name: name)
project.errors.add(:company, 'must have a valid name')
end
company
end
I was hoping that by returning an unsaved Company object, with errors set, will be a good way communicate the error (This is similar to how rails work when there's a validation error).
The problem is that when calling valid? on the company object, it removed the error I wrote there and adds the regular validation errors (in this case, company can't be blank).
And a bonus question...
And there is a conceptual problem as well: since I'm creating a model by providing parameters that are being used to create the actual attributes, they doesn't always map nicely to the errors[:attr] hash. In this case it is not so bad and I'm using the company field for the company name parameter, but I guess this can get messier when the parameters provided to the create method are less similar to the model attributes.
So what is the preferred approach to tackle that problem? Is there something basically wrong with that approach? if so, what is the preferred approach?
About overriding the default rails validation error message, you need to write your validation constraint like this:
validates_presence_of :name, :message => "must be a valid name"
I figure that it is best to avoid such nesting and stick to a shallower API.
I'm following a Rails 3.0 tutorial by lynda.com.
What's the difference between these two lines?
first_page = Page.new(:name => "First page")
first_page = Page.create(:name => "First page")
By the way, this is great tutorial; I recommend it for any other newbies like me.
Basically the new method creates an object instance and the create method additionally tries to save it to the database if it is possible.
Check the ActiveRecord::Base documentation:
create method
Creates an object (or multiple objects) and saves it to the database, if validations pass. The resulting object is returned whether the object was saved successfully to the database or not.
new method
New objects can be instantiated as either empty (pass no construction parameter) or pre-set with attributes but not yet saved (pass a hash with key names matching the associated table column names).
I have a big, flat table:
id
product_id
attribute1
attribute2
attribute3
attribute4
Here is how I want users to get to products:
See a list of unique values for attribute1.
Clicking one of those gets you a list of unique values for attribute2.
Clicking one of those gets you a list of unique values for attribute3.
Clicking one of those gets you a list of unique values for attribute4.
Clicking one of those shows you the relevant products.
I have been coding Rails for about 4 years now. I just can't unthink my current approach to this problem.
I have major writer's block. Seems like such an easy problem. But I either code it with 4 different "step" methods in my controller, or I try to write one "search" method that attempts to divine the last level you selected, and all the previous values that you selected.
Both are major YUCK and I keep deleting my work.
What is the most elegant way to do this?
Here is a solution that may be an option. Just off the top of my head and not tested (so there is probably a bit more elegant solution). You could use chained scopes in your model:
class Product < ActiveRecord::Base
scope :with_capacity, lambda { |*args| args.first.nil? ? nil : where(:capacity=>args.first) }
scope :with_weight, lambda { |*args| args.first.nil? ? nil : where(:weight=>args.first) }
scope :with_color, lambda { |*args| args.first.nil? ? nil : where(:color=>args.first) }
scope :with_manufacturer, lambda { |*args| args.first.nil? ? nil : where(:manufacturer=>args.first) }
self.available_attributes(products,attribute)
products.collect{|product| product.send(attribute)}.uniq
end
end
The code above will give you a scope for each attribute. If you pass a parameter to the scope, then it will give you the products with that attribute value. If the argument is nil, then the scope will return the full set (I think ;-). You could keep track of the attributes they are drilling down in in the session with 2 variables (page_attribute and page_attribute_value) in your controller. Then you call the entire chain to get your list of products (if you want to use them on the page). Next you can get the attribute values by passing in the set of products and the attribute name to Product.available_attributes. Note that this method (Product.available_attributes) is a total hack and would be inefficient for a large set of data, so you may want to make this another scope and use :select=>"DISTINCT(your_attribute)" or something more database efficient instead of iterating thru the full set of products as I did in the hack method.
class ProductsController < ApplicationController
def show
session[params[:page_attribute].to_sym] = params[:page_attribute_value]
#products = Product.all.with_capacity(session[:capacity]).with_weight(session[:weight]).with_color(session[:color]).with_manufacturer(session[:manufacturer])
#attr_values = Product.available_attributes(#products,params[:page_attribute])
end
end
Again, I want to warn you that I did not test this code, so its totally possible that some of the syntax is incorrect, but hopefully this will give you a starting point. Holla if you have any questions about my (psuedo) code.