I develop web application with golang.
I use the library gocraft/dbr as O/R Mapper.
I have two tables: image and entry.
I join their tables and I want to get image_url.
type Image struct {
ImageUrl dbr.NullString `db:"image_url"`
}
type Entry struct {
CompanyImageID dbr.NullInt64 `db:"company_image_id"`
CompanyImage Image
EyecatchIamgeID dbr.NullInt64 `db:"eyecatch_image_id"`
EyecatchImage Image
}
Then I tried below:
var entry Entry
sess.Select("*").From("entry").
LeftJoin(dbr.I("image").As("eyecatch_image"), "entry.eyecatch_image_id = eyecatch_image.id").
LeftJoin(dbr.I("image").As("company_image"), "entry.company_image_id = company_image.id").
Load(&entry)
log.Println("company:", entry.CompanyImage)
log.Println("eyecatch:", entry.EyecatchImage)
result:
company: {{{https://company_image_url.png true}}}
eyecatch: {{{ false}}}
I expect below, but it did not become as expected.
company: {{{https://company_image_url.png true}}}
eyecatch: {{{{http://eyecatch_image_url.png true}}}
When I tried to change join condition like below:
sess.Select("*").From("entry").
LeftJoin(dbr.I("image").As("eyecatch_image"), "entry.eyecatch_image_id = eyecatch_image.id")
Load(&entry)
result:
company: {{{http://eyecatch_image_url.png true}}}
eyecatch: {{{ false}} {{ false}}}}
I don't know how to use join with multiple conditions.
Thank you.
The documentation is really poor - it seems they gave up on the idea of publishing the library. There is an open pull request that provides a little better documentation.. Here the author describes that you can create a multiple condition like this:
cond:= dbr.And(
dbr.Or(
dbr.Gt("created_at", "2015-09-10"),
dbr.Lte("created_at", "2015-09-11"),
),
dbr.Eq("title", "hello world"),
)
Then use the condition in any statement:
sess.Select("*").From("entry").
LeftJoin(dbr.I("image").As("eyecatch_image"), cond)
Load(&entry)
Related
I am using firestore in flutter. I have to create a group like whatsapp group for that I'm getting group name, group currency,group admin and a list of members which includes fullname and phonenumber as you can see
groupadmin : "+923009399237"
groupcurrency : "USD"
groupmembers : "[
{"fullname":"ABC",
"phonenumber":"+923475894561"
},
{"fullname":"ASD",
"phonenumber":"+922222222211"
}
]"
groupname : "First Group"
I have tried something like this but it doesn't work.
Firestore.instance
.collection('groups')
.where("groupmember.phonenumber", isEqualTo: 090909090)
.snapshots()
.listen((data) {
if (data.documents.length > 0) {
}
Is there anyway to directly find the group which has member with phonenumber == 0909090909. Please help me out in this.
Worth noting that you can also add exists to your Firestore rules as well. This way you can call a Firebase Function that relies on data existing, and then safely handle success/errors by placing things within a try/catch. Note that exists counts as a Firestore read (for billing purposes).
e.g.
allow create: if exists(/databases/$(database)/documents/users/$(request.auth.uid))
See: https://firebase.google.com/docs/firestore/security/rules-conditions
Use property exists:
Firestore.instance
.collection('groups')
.where("groupmember.phonenumber", isEqualTo: 090909090)
.snapshots()
.listen((data) {
if (data.exists) console.log("Yeah !");
}
See also: What's the best way to check if a Firestore record exists if its path is known?
And please read the doc before posting https://firebase.google.com/docs/firestore
I am trying to search my database using a string, such as "A". I was just watching this Firebase tutorial Common SQL Queries converted for the Firebase Database - The Firebase Database For SQL Developers #4 and it explains that, in order to search the database for a string (in a certain location), you must use:
firebase.database().ref.child("child_name_here")
.queryOrdered(byChild: "child_name_here")
.queryStarting(atValue: "value_here_uppercase")
.queryEnding(atValue: "value_here_uppercase\\uf8ff")
You must use two \\ in the ending value as an escape character in order to get one \.
When I try this with my Firebase database, it does not work. Here is my database:
{
"Schools": {
"randomUID": {
"location" : "anyTown, anyState",
"name" : "anyName"
}
}
}
Here is my query:
databaseReference.child("Schools")
.queryOrdered(byChild: "name")
.queryStarting(atValue: "A")
.queryEnding(atValue: "A\\uf8ff") ...
When I go to print the snapshot from Firebase, I get back.
If I get rid of the ending .queryEnding(atValue: "A\\uf8ff"), the database returns all of the schools in the Schools node.
How can I search the Firebase database using a String?
queryStarting() and queryEnding() can be used for number. For example: you can get objects with someField varying from 3 to 10.
for searching string: you can search whole string using queryEqualToValue().
This shows all customers that match Wick. (It's not swift but may give you an idea)
// sample
let query = 'Wick'
clientsRef.orderByChild('name')
.startAt(query)
.endAt(query + '\uf8ff')
.once('value', (snapshot) => {
....
})
This should be a fairly simple one.
myobject has various properties, _id, name, createdBy, date etc
In my find query I want to only return specific fields from within myObject. So for example, what would I need to do to modify the find query below so that only name was returned?
myCollection.find({createdBy: someId}, {fields: {myObject: 1}}).fetch();
Currently this will return everything in myObject which it should do, I just want one field within myObject returned.
Here is a way to do it within the query:
myCollection.find({createdBy: someId}, {fields: {'myObject.name':
1}}).fetch();
Note the quotes around
'myObject.name'
Lets assume we are talking about posts, and a post document looks like this:
{
_id: 'abc123',
title: 'All about meteor',
author: {
firstName: 'David',
lastName: 'Weldon'
}
}
You can then extract all of the last names from all of the authors with this:
var lastNames = Posts.find().map(function(post) {
return post.author.lastName;
});
Modify the selector and options as needed for your collection. Using fields in this case may be a small optimization if you are running this on the server and fetching the data directly from the DB.
In couchbase, I was wondering if there was a way - WITHOUT using a view - to iterate through database keys. The admin interface appears to do this, but maybe its doing something special. What I'd like to is make a call like this to retrieve an array of keys:
$result = $cb->get("KEY_ALBERT", "KEY_FRED");
having the result be an array [KEY_ALEX, KEY_BOB, KEY_DOGBERT]
Again, I don't want to use a view unless there's no alternative. Doesn't look like its possible, but since the "view documents" in the admin appears to do this, I thought i'd double-check. I'm using the php interface if that matters.
Based on your comments, the only way is to create a simple view that emit only the id as par of the key:
function(doc, meta) {
emit( meta.id );
}
With this view you will be able to create query with the various options you need :
- pagination, range, ...
Note: you talk about the Administration Console, the console use an "internal view" that is similar to what I have written above (but not optimized)
I don't know about how couchbase admin works, but there are two options. First option is to store your docs as linked list, one doc have property (key) that points to another doc.
docs = [
{
id: "doc_C",
data: "somedata",
prev: "doc_B",
next: "doc_D"
},
{
id: "doc_D",
data: "somedata",
prev: "doc_C",
next: "doc_E"
}
]
The second approach is to use sequential id. You should have one doc that contain sequence and increment it on each add. It would be something like this:
docs = [
{
id: "doc_1",
data: "somedata"
},
{
id: "doc_2",
data: "somedata"
}
...
]
In this way you can do "range requests". To do this you form array of keys on server side:
[doc_1, doc_2 .... doc_N]and execute multiget query. Here is also a link to another example
The couchbase PHP sdk does support multiget requests. For a list of keys it will return an array of documents.
getMulti(array $ids, array $cas, int $flags) : array
http://www.couchbase.com/autodocs/couchbase-php-client-1.1.5/classes/Couchbase.html#method_getMulti
To begin with I'd like to say I know how to create ugly solutions for my problem. I am searching good solutions and best practices :)
How do I create deep hierarchial arrays (to json_encode later) from Kohana 3 ORM objects including related objects where the relation type is one-to-many?
The problem is that the ORM->as_array() method does work recursively for the "has one" and "belongs to" relationships but will stop and force you to use ->find_all() manually when you encounter a "has many" relationship.
Say I am creating a JSON API REST server using Kohana 3 and the built in ORM.
When someone looks at this URL: www.example.com/api/user?id=5
They will be served a JSON object for the user where id=5.
These are the orm-models and the relations:
User belongs to a Country
User has many Messages.
Message belongs to a Category
I would like this to work:
echo json_encode(
ORM::factory('user', 5)
->with('country')
->with('messages')
->with('messages:category')
->find()
->as_array()
);
and give me output like this:
{
name: "John"
age: 54,
country_id: 5,
country: {
name: 'Sweden',
code: 'SE'
},
messages: {
{
content: 'Lorem ipsum dolor...',
category_id: 1,
category: {...}
},
{
content: 'Sit amet elit...',
category_id: 2,
category: {...}
},
{
content: 'Consectetur ipsum dolor...',
category_id: 3,
category: {...}
}
}
}
BUT THAT WONT WORK.
This is all you would get:
{
name: "John"
age: 54,
country_id: 5,
country: {
name: 'Sweden',
code: 'SE'
}
}
Has someone forked or extended the Kohana 3 ORM to support this kind functionality?
Does someone know of any good Kohana 3 api module that takes care of this issue for you somehow?
As far as I know, there is no way to do this using only the ORM. This is the case for two reasons:
If a message has a relation for category, that usually means that category has a corresponding relation for the messages in the category. If you want to get the message "in full" - i.e. including its category - let's say that you also want to get the category "in full" - i.e. including its messages. This is obviously a very bad idea, as you could very easily design yourself into an infinite loop. In other words, if there was a magic "recurse all relations" capability, how would it know when to stop recursing?
All that the ORM is doing behind the scenes when you call find() is building a SQL query that returns a row of data from the database. However, what you are trying to do is too complicated for a single query that returns a single row. (There is a way to retrieve multiple rows as one row with comma-separated values in each field using MySQL's GROUP_CONCAT function, but I guarantee you that it is not worth the trouble.)
For both of these reasons, the ORM's with() method only works on belongs_to (in your case, the user's country and the message's category).
One way to do this query is to break it up into three steps, like this:
// Step 1: Get the user
$user = ORM::factory('user', 5)
->with('country')
->find();
// Step 2: Get the messages
$user->messages
->with('category')
->find_all();
// Step 3: Make user and the messages into arrays.
// User is easy, but messages are a little harder
// because they need to turn
// from "an object containing an array of objects"
// into "an array of arrays."
$user_arr = $user->as_array();
$fixer = function($obj)
{
return $obj->as_array();
};
$user_arr['messages'] = array_map($fixer, $user->messages->as_array());
// Now you can output it
echo json_encode($user_arr);