Database.InfluxDB.JSON

Result parsers

parseResultsWith

Arguments

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

A parser that parses a measurement. A measurement consists of

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

-> Value

JSON response

-> Parser (Vector a)

Parse a JSON response with the strictDecoder.

parseResultsWithDecoder

Arguments

:: Decoder

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

A parser that parses a measurement. A measurement consists of

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

-> Value

JSON response

-> Parser (Vector a)

Parse a JSON response with the specified decoder settings.

Decoder settings

newtype Decoder

A decoder to use when parsing a JSON response.

Use strictDecoder if you want to fail the entire decoding process if there's any failure. Use lenientDecoder if you want the decoding process to collect only successful results.

Constructors

Decoder (forall a. SomeDecoder a)

data SomeDecoder a

SomeDecoder a represents how to decode a JSON response given a row parser of type Parser a.

Constructors

forall b. SomeDecoder

Fields

• decodeEach :: Parser a -> Parser b

  How to decode each row.

  For example optional can be used to turn parse failrues into Nothings.

• decodeFold :: Parser (Vector b) -> Parser (Vector a)

  How to aggregate rows into the resulting vector.

  For example when b ~ Maybe a, one way to aggregate the values is to return only Justs.

strictDecoder :: Decoder

A decoder that fails immediately if there's any parse failure.

strictDecoder is defined as follows:

strictDecoder :: Decoder
strictDecoder = Decoder $ SomeDecoder
 { decodeEach = id
 , decodeFold = id
 }

lenientDecoder :: Decoder

A decoder that ignores parse failures and returns only successful results.

Getting fields and tags

getField

Arguments

:: MonadFail m

=> Text

Column name

-> Vector Text

Columns

-> Vector Value

Field values

-> m Value

Get a field value from a column name

getTag

Arguments

:: MonadFail m

=> Text

Tag name

-> HashMap Text Value

Tags

-> m Value

Get a tag value from a tag name

Common JSON object parsers

parseJSON :: FromJSON a => Value -> Parser a

parseUTCTime :: Precision ty -> Value -> Parser UTCTime

Parse either a POSIX timestamp or RFC3339 formatted timestamp as UTCTime.

parsePOSIXTime :: Precision ty -> Value -> Parser POSIXTime

Parse either a POSIX timestamp or RFC3339 formatted timestamp as POSIXTime.

parseRFC3339 :: ParseTime time => Value -> Parser time

Parse a RFC3339-formatted timestamp.

Note that this parser is slow as it converts a Text input to a String before parsing.

Utility functions

parseResultsObject :: Value -> Parser (Vector Value)

Parse a result response.

parseSeriesObject :: Value -> Parser (Vector Value)

Parse a series response.

parseSeriesBody :: Value -> Parser (Maybe Text, HashMap Text Text, Vector Text, Array)

Parse the common JSON structure used in query responses.

parseErrorObject :: Value -> Parser String

Parse the common JSON structure used in failure response. >>> A.parse parseErrorObject $ fromJust $ decode "{ "error": "custom error" }" Success "custom error" >>> A.parse parseErrorObject $ fromJust $ decode "{ "message": "custom error" }" Success "custom error"