How to communicate with Neo via HTTP in Go

📌

For smooth practice, the following query should be run to prepare tables and data.

CREATE TAG TABLE IF NOT EXISTS EXAMPLE (
    NAME VARCHAR(20) PRIMARY KEY,
    TIME DATETIME BASETIME,
    VALUE DOUBLE SUMMARIZED
);

If you are a Go programmer and prefer to write RESTful API client, this is the way to go.

Step 1.

Find full source code from github

Step 2.

Copy source code and save it as http_wave.go or just run script below

curl -o http_wave.go "https://raw.githubusercontent.com/machbase/neo-docs/main/examples/go/http_wave/http_wave.go"

Step 3.

go run http_wave.go

This Go code generates sine & cosine wave data and writes them into EXAMPLE table.

Code explains

Define data structure that represents the payload of write API.

type WriteReq struct {
    Table string       `json:"table"`
    Data  WriteReqData `json:"data"`
}

type WriteReqData struct {
    Columns []string `json:"columns"`
    Rows    [][]any  `json:"rows"`
}

The API for writing data via HTTP is explained in here and it expects to receive JSON payload.

We can prepare payload like below code, so that write multiple records within a payload. Assume sin, cos variables are properly initialized float64 values.

content, _ := json.Marshal(&WriteReq{
    Data: WriteReqData{
        Columns: []string{"name", "time", "value"},
        Rows: [][]any{
            {"wave.sin", ts.UTC().UnixNano(), sin},
            {"wave.cos", ts.UTC().UnixNano(), cos},
        },
    },
})

It will be encoded as JSON for writing API like below.

{
    "data": {
        "columns":["name", "time", "value"],
        "rows": [
            [ "wave.sin", 1670380342000000000, 1.1 ],
            [ "wave.cos", 1670380343000000000, 2.2 ]
        ]
    }
}

Send it to server via http POST request.

client := http.Client{}
rsp, err := client.Post("http://127.0.0.1:5654/db/write/EXAMPLE", 
    "application/json", bytes.NewBuffer(content))

Server replies HTTP 200 OK if it successfully writes data.

Last updated on Sep 27, 2023

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