Using sqlx as my database adapter, I'd like to run queries on user profiles based on user-submitted POST data. There are several parameters like age, sex and location and many more.
So for example if only age value is submitted by the user, the query should looks like:
var profiles []model.Profile
q:= "SELECT * FROM profile WHERE age = ?"
err = database.SQL.Select(&profiles, q, age)
if err != nil {
log.Println(err)
}
As you can see, since the query can not be built dynamically, this method is not flexible enough and becomes so verbose to account for all possible variations.
What I want is to construct query based on the input data then just feed the raw query to sqlx.
Something like this pseudo code:
q:= `SELECT * FROM profile WHERE
age > 25 AND sex="f" AND location="London"`
err = database.SQL.ExecRaw(&profiles, q)
How can I achieve this in sqlx?
I have looked at the docs but could not figure out how to do so.
If you don't want to use parameters, don't use parameters. Select doesn't prevent you from putting literals in your query.
Related
I am working on an api which takes in parameters for filters (as given below)
/api/endpoint?filter_key_1=filter_value_1&...
I've previously worked on spring where the criteria API allows for dynamically building SQL queries without much hassle. In golang I'm using gorm for handling the ORM operations. Is there anyway to build the queries with optional parameters without writing redundant code?.
For example:
If the request sent is:
/api/endpoint?fk_1=fv_1&fk_2=fv_2&fk_3=fv_3
Query generated should be :
select * from table where fk_1 = fv_1 AND fk_2 = fv_2 AND fk_3 = fv_3
but in case of :
/api/endpoint?fk_1=fv_1
Query generated should be:
select * from table where fk_1 = fv_1
Currently my approach is to check if each variable is present and build the query as a string :
query:="select * from table where "
if fk_1 != ""{
query += "fk_1 = fv_1"
}
... and so on
but this seems very awkward and error prone
Any help will be appreciated! Thanks
EDIT
Building on #bjornaer's answer what helped me was to get the map[string][]string in a form that I can send the same to gorm, map[string]interface{}.
This thread will help in the same.
Now there's no longer a need for redundant checks or string operations in the filters
so it seems to me your question has 2 parts:
you need to retrieve your query values from your url and
insert them to your db query
I don't see how you are handling your requests so let's assume you use the http package: from req.URL you get the URL object and from that calling the Query() method yields a map[string][]string of your query parameters, with those in a variable URLQuery let's pause and look at how you query with gorm:
db, err := gorm.Open(sqlite.Open("gorm.db"), &gorm.Config{
QueryFields: true,
})
here I open a sqlite, then you can pass a variable reference to fill with your query, for example:
result := db.Where(map[string]interface{}{"name": "jinzhu", "age": 20}).Find(&users)
now from the example above, replace your variable in:
result := db.Where(map[string]interface{}URLQuery).Find(&users)
you can find it in the docs
I want to read all entities from a Datastore kind (around 6 entities/records).
I have a Datastore that is key'ed on a weird type that I am trying to understand. I can't find any uniqueness on the a key to perform a query on.
The table looks like this:
GCP Datastore representing data I want to read into my Go app
When I click on a record, it looks like this:
Key literal exposed and used from here on out to try and get the records in the Go app
``I can perform an ancestor query in the console like this:```
GCP Datastore queried using Ancestor query
Great! So now I want to retrieve this data from my Golang App? But how?
I see a lot of solutions online about using q.Get(...) // where q is a *Query struct
Any of these solutions won't work because they import google.golang.org/appengine/datastore. I understand that this is legacy and deprecated. So I want a solution that imports cloud.google.com/go/datastore.
I tried something along these lines but didn't get much luck:
First try using GetAll and query
I tried this next:
Second try attempting to use ancestor query... not ready yet
Lastly I tried to get a single record directly:
Lastly I tried to get the record directly
In all cases, my err is not nil and the dts that should be populated from datastore query is also nil.
Any guidance to help me understand how to query on this key type? Am I missing something fundamental with the way this table is key'ed and queried?
Thank you
Then I tried this:
It seems you are just missing your Namespace
// Merchant Struct
type MerchantDetails struct {
MEID string
LinkTo *datastore.Key
Title string
}
// Struct array to store in
var tokens []MerchantDetails
// Ancestor Key to filter by
parentKey := datastore.NameKey("A1_1113", "activate", nil)
parentKey.Namespace = "Devs1"
// The call using the new datastore UI. Basically query.Run(), but datastore.GetAll()
keys, err := helpers.DatastoreClient.GetAll(
helpers.Ctx,
datastore.NewQuery("A1_1112").Ancestor(parentKey).Namespace("Devs1"),
&tokens,
)
if err != nil {
return "", err
}
// Print all name/id from the found values
fmt.Printf("keys: %v", keys)
My Kind has 3 entities: FirstName, FamilyName and Email.I want to retrieve only the Key and the FirstName associated with the entity. Like this in SQL : SELECT Id,FirstName from users;
In go-lang, I tried fetching all the data in the Kind like this
q := datastore.NewQuery(dataKind)
and then to get the keys, I do this:
keys, err := q.GetAll(ctx, &users)
I don't want to fetch all the properties, instead only the keys and the FirstName. I was wondering if there is a way to do it in a single datastore query? As mentioned earlier in my previous question, I'm new to go-lang and datastore. Please help
Use Project to select a single property. The property must be indexed. The query does not return entities where the property is not set.
The following snippet returns the keys and users with only the FristName field set:
q := datastore.NewQuery(dataKind).Project("FirstName")
keys, err := client.GetAll(ctx, q, &users)
I have the following query in GQL:
"SELECT * FROM Task WHERE Uuid = \"FOOBAR\" ORDER BY CreateTimeMs DESC LIMIT 1"
How can I directly run this query in Golang?
query := datastore.NewQuery("SELECT * FROM Task WHERE Uuid = \"FOOBAR\" ORDER BY CreateTimeMs DESC LIMIT 1") seems to be incorrect.
UPDATE:
I am very aware of the Query types. The thing is that I would like to use GQL directly instead of translating them into Query types.
I was searching to solve exactly the same problem when I came across this note in the GQL documentation:
Note: Google Cloud Client Library for Java and Google Cloud Client Library for Ruby support GQL, but other Google Cloud client libraries do not.
So that's a no-go ...
However, it should be feasible to implement it over the REST api projects.runQuery but then you have to unmarshal the result into structs by yourself.
Take a look at the Query type documentation, from looking at its methods and reading their respective documentation you should be able to understand how to translate your SQL into datastore.Query specific method calls.
For example your sql can be written as:
q := datastore.NewQuery("Task").Filter("Uuid =", "FOOBAR").Order("-CreateTimeMs").Limit(1)
This just builds your Query value, to get the actual result you need to run the query to get an iterator whose Next method can be used to read the result.
If you want to avoid the run-iterate-next dance you can use the GetAll query method.
var tt = []*Task{}
q := datastore.NewQuery("Task").Filter("Uuid =", "FOOBAR").Order("-CreateTimeMs").Limit(1)
if _, err := q.GetAll(tt); err != nil {
panic(err)
}
log.Println(tt[0]) // your task
Read more here:
Datastore Queries
Retrieving query results
Query Restrictions
Query Cursors
I am using Golang and Firego for connecting to Firebase. I am trying to search an admin with Email: john#gmail.com. The following is my Database Structure
For this I have tried:
dB.Child("CompanyAdmins").Child("Info").OrderBy("Email").EqualTo("john#gmail.com").Value(&result)
but it does not produce expected result. How can I do this?
While #dev.bmax has the problem identified correctly, the solution is simpler. You can specify the path of a property to order on:
dB.Child("CompanyAdmins")
.OrderBy("Info/Email")
.EqualTo("john#gmail.com")
.Value(&result)
Update (2017-02-10):
Full code I just tried:
f := firego.New("https://stackoverflow.firebaseio.com", nil)
var result map[string]interface{}
if err := f.Child("42134844/CompanyAdmins").OrderBy("Info/Email").EqualTo("john#gmail.com").Value(&result); err != nil {
log.Fatal(err)
}
fmt.Printf("%s\n", result)
This prints:
map[-K111111:map[Info:map[Email:john#gmail.com]]]
Which is the exact place where I put the data.
Update 20170213:
This is the index I have defined:
"CompanyAdmins": {
".indexOn": "Info/Email"
}
If this doesn't work for you, please provide a similarly complete snippet that I can test.
Can you put Info data directly into CompanyAdmins structure? This way, your query will work.
CompanyAdmins
-id
-Email: "johndon#gmail.com"
-Settings:
- fields
The problem with your query, is that Info is not a direct child of CompanyAdmins.
You could use the email as the key instead of an auto-generated one when you insert values. That way, you can access the admin directly:
dB.Child("CompanyAdmins").Child("john#gmail.com").Child("Info")
Otherwise, you need to restructure the database. Your order-by field (email) should be one level higher, like Rodrigo Vinicius suggests. Then, your query will change to:
dB.Child("CompanyAdmins").OrderBy("Email").EqualTo("john#gmail.com")