I'm very new to MongoDB, i tell you sorry for this question but i have a problem to understand how to create a document that can contain a value with different "type:
My document can contain data like this:
// Example ONE
{
"customer" : "aCustomer",
"type": "TYPE_ONE",
"value": "Value here"
}
// Example TWO
{
"customer": "aCustomer",
"type": "TYPE_TWO",
"value": {
"parameter1": "value for parameter one",
"parameter2": "value for parameter two"
}
}
// Example THREE
{
"customer": "aCustomer",
"type": "TYPE_THREE",
"value": {
"anotherParameter": "another value",
{
"someParameter": "value for some parameter",
...
}
}
}
Customer field will be even present, the type can be different (TYPE_ONE, TYPE_TWO and so on), based on the TYPE the value can be a string, an object, an array etc.
Looking this example, i should create three kind of collections (one for type) or the same collection (for example, a collection named "measurements") can contain differend kind of value on the field "value" ?
Trying some insert in my DB instance i dont get any error (i'm able to insert object, string and array on property value), but i would like to know if is the correct way...
I come from RDBMS, i'm a bit confused right now.. thanks a lot for your support.
You can find the answer here https://docs.mongodb.com/drivers/use-cases/product-catalog
MongoDB's dynamic schema means that each need not conform to the same schema.
Related
I'd like to fetch snapshot which contains typed text. For example node look like this
"Team": {
"Yankees": {
"uid1": "name",
"uid2": "name"
},
"Angels": {
"uid1": "name"
"uid3": "name"
}
and if user typed yan in search bar then I want to fetch "Yankees" snapshot. I saw some document and stack over flow post and tried like so
ref.child("Team").queryStarting(atValue: "yan").queryEnding(atValue: "yan\u{f8ff}").observe
but it doesn't work. How can I do this? Thank you!
Firebase searches are case sensitive. Since your key starts with an uppercase Y, the query only matches if it also does that:
ref.child("Team")
.queryOrderedByKey()
.queryStarting(atValue: "Yan")
.queryEnding(atValue: "Yan\u{f8ff}").observe
I also queryOrderedByKey() to be explicit about what you want to order/filter on.
If you want to allow case-insensitive filtering, the typical approach is to add a property with the all-lowercase value to each team:
"Team": {
"Yankees": {
"teamNameForSearch": "yankees",
"uid1": "name",
"uid2": "name"
},
"Angels": {
"teamNameForSearch": "angels",
"uid1": "name"
"uid3": "name"
}
Now you can search with:
ref.child("Team")
.queryOrdered(byChild: "teamNameForSearch")
.queryStarting(atValue: "yan")
.queryEnding(atValue: "yan\u{f8ff}").observe
A final note is that both approaches only do so-called prefix matches: they find teams whose name starts with what the user typed. If you want a contains operation (as the title of your question suggests), you will have to look beyond Firebase for a solution. For more on that, see Kato's answer here: Firebase query - Find item with child that contains string
You need to change the db to this:
"Team": {
"randomid": {
"team":"Yankees",
"uid1": "name",
"uid2": "name"
},
"randomid": {
"team":"Angels"
"uid1": "name"
"uid3": "name"
}
and now you can do this:
ref.child("Team").queryOrdered(byChild: "team").queryStarting(atValue: "Yan").queryEnding(atValue: "Yan\u{f8ff}").observe
First in your query above, you need to use queryOrdered() to know which child you want to order.
Also in your database the node Team is not equal to anything, it is a parent node that has child nodes.
So to fix this, the node Team needs to be equal to a value(like in the database in this answer) so you will be able to order it and use queryStarting and queryEnding on it.
Using the FIWARE PointOfInterest data model I would like to filter by POI category which is an array. For instance
http://130.206.118.244:1027/v2/entities?type=PointOfInterest&options=keyValues&attrs=name,category&limit=100&q=category=="311"
having as entity instances something like
{
"id": "Museum-f85a8c66d617c23d33847f8110341a29",
"type": "PointOfInterest",
"name": "The Giant Squid Centre",
"category":
[
"311"
]
},
{
"id": "Museum-611f228f42c7fbfa4bd58bad94455055",
"type": "PointOfInterest",
"name": "Museo Extremeño e Iberoamericano de Arte Contemporáneo",
"category":
[
"311"
]
},
Looking to the NGSIv2 specification it seems that works in the way you mention:
Single element, e.g. temperature==40. For an entity to match, it must contain the target property (temperature) and the target property value must be the query value (40) (or include the value, in case the target property value is an array).
I mean, in particular the part that says:
...or include the value, in case the target property value is an array.
I am faced with a problem where I am not sure which path to take. So I am asking it here. I have an application where there can be products and there can be metadata for a product. These metadata can be created and deleted from the front end. So let's say, today a each product has two meta data (e.g. Name, Price) then tomorrow it can be three, four or more or even less than two. So this is dynamic. I am trying to represent the data as follows
Product =
{
"_id": mongo
"Name": string
"Description": string
"BasePrice": number
"CreatedBy": user mongo _id
"CreatedAt": timestamp
"ModifiedAt": timestamp
"MetaData": BSON object (having all the keys from ProductMetadata collection and their values. e.g. {"Category": "table ware", "Material": "oak wood, copper", "Length": 5.6})
}
ProductMetadata =
{
"_id": mongo
"Name": string (e.g. - "Category" or "Material" or "Height")
"Type": string (indicating what kind of value it can hold like string/integer/array. e.g. - "string")
"CreatedAt": timestamp
"ModifiedAt": timestamp
}
As you can see this is a pure dynamic situation so having a structure at the code level which represent the model is impossible.
My problem is, how do I implement such a thing using mgo and Go lang? If I need to use reflection then can some one please point me towards a good blog/tutorial where I can get a little bit more info. Or if you think that there is a fundamental problem in the approach of modeling the data then please correct me so that it can be easily implemented using Go.
In Python, it would not be a problem to implement this. I know that. But I am confused about the Go implementation.
Please help.
Thanks in advance
If Keys for metadata are unique, why not just use a map.
meaning your Product struct looks like:
struct Product {
ID bson.ObjectId `bson:"_id,omitempty"`
Name string
Description string
... omitted other fields ...
MetaData map[string]map[string]interface{} // map of string -> map of string -> anything
}
If you can have more than one instance of a given meta data, ie: 2 categories, use a list:
struct Product {
ID bson.ObjectId `bson:"_id,omitempty"`
Name string
Description string
... omitted other fields ...
MetaData []map[string]interface{} // list of maps of string -> anything
}
As I create entities in an Orion server, I can search by ID, as flat or using regular expressions:
http://<localhost>:1026/v1/queryContext
Content:
{
"entities": [
{
"type": "Sensor",
"isPattern": "true",
"id": "sensor_1.*"
}
],
"attributes": ["temperature","humidity"]
}
In the above example I'd get all objects of type "Sensor" whose ID starts with "sensor_1", and their attributes "temperature" and "humidity". I wonder if there is any way that would allow me to search by specific attribute value, for example to get those sensors whose humidity is over "60.2", or this selection must be done over the retrieved data queried by ID.
Not in the current Orion version (0.19.0) but it will be possible in the future. Have a look to the attribute::<name> filter with the = operator in this document.
I want to retrive record which are matching to booking's client id & want to show it to client. I am doing the following:
$mongoDb = $mongoDb->selectCollection('booking');
$bookingInfo = $mongoDb->find(array("client.id" => $_SESSION['client_id']));
My mongo database record looks like this:
"paymentDue": "",
"client": {
"contacts": [
{
"name": "loy furison",
"email": "loy#hotmail.com"
}
],
"id": "5492abba64363df013000029",
"name": "Birdfire"
},
want to fire the query with key value as client.id in find function. But this query doesnt work..whats the issue
I got a little logic that is different by key name only. If i find it with client.name then i shows me records & there i need to insert these in json object & then through foreach loop each record if i retrive & compare then it works...got it but the expected doesnt work why?????...didnt get:-!