Database.InfluxDB.Query

Query interface

data Query

An InfluxDB query.

A spec of the format is available at https://docs.influxdata.com/influxdb/v1.2/query_language/spec/.

A Query can be constructed using either

• the IsString instance with -XOverloadedStrings
• or formatQuery.

>>> :set -XOverloadedStrings
>>> "SELECT * FROM series" :: Query
"SELECT * FROM series"
>>> import qualified Database.InfluxDB.Format as F
>>> formatQuery ("SELECT * FROM "%F.key) "series"
"SELECT * FROM \"series\""

NOTE: Currently this library doesn't support type-safe query construction.

Instances

Show Query

Methods

showsPrec :: Int -> Query -> ShowS

show :: Query -> String

showList :: [Query] -> ShowS

IsString Query

Methods

fromString :: String -> Query

query :: QueryResults a => QueryParams -> Query -> IO (Vector a)

Query data from InfluxDB.

It may throw InfluxException.

queryChunked

Arguments

:: QueryResults a

=> QueryParams

-> Optional Int

Chunk size

By Default, InfluxDB chunks responses by series or by every 10,000 points, whichever occurs first. If it set to a Specific value, InfluxDB chunks responses by series or by that number of points.

-> Query

-> FoldM IO (Vector a) r

-> IO r

Same as query but it instructs InfluxDB to stream chunked responses rather than returning a huge JSON object. This can be lot more efficient than query if the result is huge.

It may throw InfluxException.

Query parameters

data QueryParams

The full set of parameters for the query API

Instances

HasCredentials QueryParams

Authentication info for the query

>>> let p = queryParams "foo"
>>> p ^. authentication
Nothing
>>> let p' = p & authentication ?~ credentials "john" "passw0rd"
>>> p' ^. authentication.traverse.user
"john"

Methods

authentication :: Lens' QueryParams (Maybe Credentials)

HasManager QueryParams

>>> let p = queryParams "foo" & manager .~ Left HC.defaultManagerSettings

Methods

manager :: Lens' QueryParams (Either ManagerSettings Manager)

HasDatabase QueryParams

>>> let p = queryParams "foo"
>>> p ^. database
"foo"

Methods

database :: Lens' QueryParams Database

HasServer QueryParams

>>> let p = queryParams "foo"
>>> p ^. server.host
"localhost"

Methods

server :: Lens' QueryParams Server

HasPrecision QueryRequest QueryParams

Returning JSON responses contain timestamps in the specified precision/format.

>>> let p = queryParams "foo"
>>> p ^. precision
RFC3339

Methods

precision :: Lens' QueryParams (Precision QueryRequest)

queryParams :: Database -> QueryParams

Smart constructor for QueryParams

Default parameters:

server

defaultServer

precision

RFC3339

authentication

Nothing

manager

Left defaultManagerSettings

server :: HasServer a => Lens' a Server

InfluxDB server address and port that to interact with.

database :: HasDatabase a => Lens' a Database

Database name to work on.

precision :: HasPrecision ty a => Lens' a (Precision ty)

Time precision parameter.

manager :: HasManager a => Lens' a (Either ManagerSettings Manager)

HTTP manager settings or a manager itself.

If it's set to ManagerSettings, the library will create a Manager from the settings for you.

Parsing results

class QueryResults a where

Types that can be converted from an JSON object returned by InfluxDB.

For example the h2o_feet series in the official document can be encoded as follows:

>>> :{
data H2OFeet = H2OFeet
  { time :: UTCTime
  , levelDesc :: T.Text
  , location :: T.Text
  , waterLevel :: Double
  }
instance QueryResults H2OFeet where
  parseResults prec = parseResultsWith $ \_ _ columns fields -> do
    time <- getField "time" columns fields >>= parseUTCTime prec
    String levelDesc <- getField "level_description" columns fields
    String location <- getField "location" columns fields
    FieldFloat waterLevel <-
      getField "water_level" columns fields >>= parseQueryField
    return H2OFeet {..}
:}

Minimal complete definition

parseResults

Methods

parseResults :: Precision QueryRequest -> Value -> Parser (Vector a)

Parse a JSON object as an array of values of expected type.

Instances

QueryResults Void

Methods

parseResults :: Precision QueryRequest -> Value -> Parser (Vector Void)

QueryResults ShowSeries

Methods

parseResults :: Precision QueryRequest -> Value -> Parser (Vector ShowSeries)

QueryResults ShowQuery

Methods

parseResults :: Precision QueryRequest -> Value -> Parser (Vector ShowQuery)

((~) * a Value, (~) * b Value) => QueryResults (a, b)

Methods

parseResults :: Precision QueryRequest -> Value -> Parser (Vector (a, b))

((~) * a Value, (~) * b Value, (~) * c Value) => QueryResults (a, b, c)

Methods

parseResults :: Precision QueryRequest -> Value -> Parser (Vector (a, b, c))

((~) * a Value, (~) * b Value, (~) * c Value, (~) * d Value) => QueryResults (a, b, c, d)

Methods

parseResults :: Precision QueryRequest -> Value -> Parser (Vector (a, b, c, d))

((~) * a Value, (~) * b Value, (~) * c Value, (~) * d Value, (~) * e Value) => QueryResults (a, b, c, d, e)

Methods

parseResults :: Precision QueryRequest -> Value -> Parser (Vector (a, b, c, d, e))

((~) * a Value, (~) * b Value, (~) * c Value, (~) * d Value, (~) * e Value, (~) * f Value) => QueryResults (a, b, c, d, e, f)

Methods

parseResults :: Precision QueryRequest -> Value -> Parser (Vector (a, b, c, d, e, f))

((~) * a Value, (~) * b Value, (~) * c Value, (~) * d Value, (~) * e Value, (~) * f Value, (~) * g Value) => QueryResults (a, b, c, d, e, f, g)

Methods

parseResults :: Precision QueryRequest -> Value -> Parser (Vector (a, b, c, d, e, f, g))

((~) * a Value, (~) * b Value, (~) * c Value, (~) * d Value, (~) * e Value, (~) * f Value, (~) * g Value, (~) * h Value) => QueryResults (a, b, c, d, e, f, g, h)

Methods

parseResults :: Precision QueryRequest -> Value -> Parser (Vector (a, b, c, d, e, f, g, h))

parseResultsWith

Arguments

:: (Maybe Text -> HashMap Text Text -> Vector Text -> Array -> Parser a)

A parser that takes

1. an optional name of the series
2. a map of tags
3. an array of field names
4. an array of values

to construct a value.

-> Value

-> Parser (Vector a)

A helper function to parse a JSON response in parseResults.

Low-level functions

withQueryResponse

Arguments

:: QueryParams

-> Maybe (Optional Int)

Chunk size

By Nothing, InfluxDB returns all matching data points at once. By Just Default, InfluxDB chunks responses by series or by every 10,000 points, whichever occurs first. If it set to a Specific value, InfluxDB chunks responses by series or by that number of points.

-> Query

-> (Request -> Response BodyReader -> IO r)

-> IO r