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31edca3b06
11
go.mod
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11
go.mod
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module test_server
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go 1.24.2
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require (
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github.com/jackc/pgpassfile v1.0.0 // indirect
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github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 // indirect
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github.com/jackc/pgx/v5 v5.7.4 // indirect
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golang.org/x/crypto v0.31.0 // indirect
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golang.org/x/text v0.21.0 // indirect
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)
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17
go.sum
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17
go.sum
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github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
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github.com/jackc/pgpassfile v1.0.0 h1:/6Hmqy13Ss2zCq62VdNG8tM1wchn8zjSGOBJ6icpsIM=
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github.com/jackc/pgpassfile v1.0.0/go.mod h1:CEx0iS5ambNFdcRtxPj5JhEz+xB6uRky5eyVu/W2HEg=
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github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 h1:iCEnooe7UlwOQYpKFhBabPMi4aNAfoODPEFNiAnClxo=
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github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761/go.mod h1:5TJZWKEWniPve33vlWYSoGYefn3gLQRzjfDlhSJ9ZKM=
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github.com/jackc/pgx/v5 v5.7.4 h1:9wKznZrhWa2QiHL+NjTSPP6yjl3451BX3imWDnokYlg=
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github.com/jackc/pgx/v5 v5.7.4/go.mod h1:ncY89UGWxg82EykZUwSpUKEfccBGGYq1xjrOpsbsfGQ=
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github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
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github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
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github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
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github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
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golang.org/x/crypto v0.31.0 h1:ihbySMvVjLAeSH1IbfcRTkD/iNscyz8rGzjF/E5hV6U=
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golang.org/x/crypto v0.31.0/go.mod h1:kDsLvtWBEx7MV9tJOj9bnXsPbxwJQ6csT/x4KIN4Ssk=
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golang.org/x/text v0.21.0 h1:zyQAAkrwaneQ066sspRyJaG9VNi/YJ1NfzcGB3hZ/qo=
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golang.org/x/text v0.21.0/go.mod h1:4IBbMaMmOPCJ8SecivzSH54+73PCFmPWxNTLm+vZkEQ=
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gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
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gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
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3
index.html
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3
index.html
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<body>
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Hello World!
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</body>
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241
main.go
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241
main.go
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package main
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import (
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"net/http"
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"fmt"
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"encoding/json"
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"os"
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"context"
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"github.com/jackc/pgx/v5"
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)
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//mixed opinions on global variables online, need production example to verify this practice
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var conn = ConnectPostgres()
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//----------------------------------------------------------------------------------------------------
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//root that returns a static string
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func RootHandler(w http.ResponseWriter, r *http.Request) {
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fmt.Fprintln(w, "Hello World!")
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}
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//----------------------------------------------------------------------------------------------------
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//json struct for incoming requests
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type IncomingJson struct {
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Message string `json:"message"`
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}
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//take note that for structs, Capitalised fields indicates exported fields, and vice versa
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//therefore "name string" will not be decoded/encoded, but "Name string" will
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//the `json:name`
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//json struct for api response
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type OutboundJson struct {
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Status string `json:"status"`
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RequestData IncomingJson `json:"request_data"`
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}
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//API that accepts and returns a json defined in the struct above
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func JsonHandler(w http.ResponseWriter, r *http.Request){
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//checks if the method is Post, returns error if not
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if r.Method != http.MethodPost {
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http.Error(w, "Method not allowed,Only Post Requests", http.StatusMethodNotAllowed)
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return
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}
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//decode Json from request body, returns error if doesnt fit struct
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var incoming IncomingJson
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err := json.NewDecoder(r.Body).Decode(&incoming)
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if err != nil {
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http.Error(w,"Bad Request, Failed to parse body({message:str})", http.StatusBadRequest)
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return
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}
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//set response header to json
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w.Header().Set("Content-Type", "application/json")
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//encode and set response
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resp := OutboundJson{
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Status: "received",
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RequestData: incoming,
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}
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err = json.NewEncoder(w).Encode(resp)
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if err != nil {
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fmt.Println("JSON encoding Error:",err)
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http.Error(w, "Error encoding JSON", http.StatusInternalServerError)
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return
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}
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}
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//----------------------------------------------------------------------------------------------------
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func ConnectPostgres()(*pgx.Conn){
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//yes i need to put this in a .env, im just testing for now and this database has nothing important
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conn, err := pgx.Connect(context.Background(), "postgres://postgres:12345678@localhost:5432/postgres")
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if err != nil {
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fmt.Println("Unable to connect to database", err)
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os.Exit(1)
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}
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fmt.Println("Connected to database")
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return conn
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}
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//operation dictates which CRUD operation to perform (c,r,u,d)
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//identifier dictates which row the operation is performed on (int)
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//value dictates the actual change of operation
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type IncomingPostgres struct{
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Operation string `json:"operation"`
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Identifier int `json:identifier",omitempty`
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Value string `json:"value",omitempty`
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}
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type OutgoingPostgres struct{
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Identifier int `json:"identifier"`
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Value string `json:"value"`
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Status string `json:"status"`
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}
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//the pointed table only has two columns: id(int) and value(str)
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//the following handler provides a simple example on handling CRUD operations via an API using pgx
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func PostgresHandler(w http.ResponseWriter, r *http.Request){
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//checks if the method is Post, returns error if not
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if r.Method != http.MethodPost {
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http.Error(w, "Method not allowed,Only Post Requests", http.StatusMethodNotAllowed)
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return
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}
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//decode Json from request body, returns error if doesnt fit struct
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var incoming IncomingPostgres
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err := json.NewDecoder(r.Body).Decode(&incoming)
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if err != nil {
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http.Error(w,"Bad Request, Failed to parse body({operation:str,identifier[optional]:int,value[optional]:string})", http.StatusBadRequest)
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return
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}
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//map of allowed inputs for the operation field, returns error if doesnt fit
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allowed_operations := map[string]bool {
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"c":true,
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"r":true,
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"u":true,
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"d":true,
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}
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if !allowed_operations[incoming.Operation] {
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http.Error(w, "Bad Request, operation field only allows the following inputs: {c,r,u,d}", http.StatusBadRequest)
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return
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}
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//switch case to determine the operation
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//this method directly checks for zero values, which might not be feasible if zero values are allowed inputs
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//consider transforming the struct into a map then checking if it exists, that would be a more robust method
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var id int
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var value string
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switch incoming.Operation{
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case "c":
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if incoming.Value != ""{
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fmt.Println("create",incoming.Value)
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//SQL query for the db
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rows, err := conn.Query(context.Background(),"INSERT INTO test_table (value) VALUES ($1) RETURNING(id)",incoming.Value)
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if err != nil{
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fmt.Println(err)
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http.Error(w,"Server Error, something is wrong", http.StatusInternalServerError)
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return
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}
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//close the connection when the function is finished
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defer rows.Close()
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if rows.Next(){
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err = rows.Scan(&id)
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if err != nil{
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fmt.Println(err)
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http.Error(w,"Server Error, Scanning Failed",http.StatusInternalServerError)
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return
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}
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}
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value = incoming.Value
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} else {
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http.Error(w,"Bad Request, Value Key is needed for create operation",http.StatusBadRequest)
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return
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}
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case "r":
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if incoming.Identifier != 0{
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fmt.Println("read",incoming.Identifier)
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//SQL query for the db
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rows, err := conn.Query(context.Background(),"SELECT id,value FROM test_table WHERE id=$1",incoming.Identifier)
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if err != nil{
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fmt.Println(err)
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http.Error(w, "Server Error, something is wrong", http.StatusInternalServerError)
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return
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}
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//close the connection when the function is finished
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defer rows.Close()
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//this is a readone() method, only the first item queried will be considered and returned
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if rows.Next(){
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err = rows.Scan(&id,&value)
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if err != nil{
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http.Error(w,"Server Error, Scanning Failed",http.StatusInternalServerError)
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return
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}
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} else {
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http.Error(w,"Not Found, identifier does not exist",http.StatusNotFound)
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return
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}
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} else {
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http.Error(w,"Bad Request, Identifier Key is needed for read operation",http.StatusBadRequest)
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return
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}
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case "u":
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if incoming.Identifier != 0 && incoming.Value != ""{
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fmt.Println("update",incoming.Identifier,incoming.Value)
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_, err := conn.Query(context.Background(),"UPDATE test_table SET value=$1 WHERE id=$2",incoming.Value,incoming.Identifier)
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if err != nil{
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fmt.Println(err)
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http.Error(w,"Update Failed, double check if identifier exists",http.StatusBadRequest)
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return
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}
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id = incoming.Identifier
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value = incoming.Value
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} else {
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http.Error(w,"Bad Request, Identifier Key and Value Key is needed for update operation",http.StatusBadRequest)
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return
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}
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case "d":
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if incoming.Identifier != 0{
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fmt.Println("delete",incoming.Identifier)
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_,err := conn.Query(context.Background(),"DELETE FROM test_table WHERE id=$1",incoming.Identifier)
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if err != nil{
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fmt.Println(err)
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http.Error(w,"Delete Failed, double check if identifier exists",http.StatusBadRequest)
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return
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}
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value = incoming.Value
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id = incoming.Identifier
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} else {
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http.Error(w,"Bad Request, Value Key is needed for create operation",http.StatusBadRequest)
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return
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}
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}
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w.Header().Set("Content-Type","application/json")
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resp := OutgoingPostgres{
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Status: "Successful",
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Identifier: id,
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Value: value,
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}
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json.NewEncoder(w).Encode(resp)
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}
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//----------------------------------------------------------------------------------------------------
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//main entry function to register routes and serve
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func main() {
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defer conn.Close(context.Background())
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http.HandleFunc("/pgx",PostgresHandler)
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http.HandleFunc("/json", JsonHandler)
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http.HandleFunc("/", RootHandler)
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fmt.Println("Starting server at http://localhost:8080")
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err := http.ListenAndServe(":8080", nil)
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if err != nil {
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fmt.Println("Error starting server:", err)
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}
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}
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