api: add function to retrieve column info for a table or view

This is called using the path "/v1/columns" on the API server.

Author: justinclift

api/handlers.go

@@ -10,6 +10,67 @@ import (
 	com "github.com/sqlitebrowser/dbhub.io/common"
 )
 
+// columnsHandler returns the list of columns present in a table or view
+// This can be run from the command line using curl, like this:
+//   $ curl -F apikey="YOUR_API_KEY_HERE" -F dbowner="justinclift" -F dbname="Join Testing.sqlite" https://api.dbhub.io/v1/columns
+//   * "apikey" is one of your API keys.  These can be generated from your Settings page once logged in
+//   * "dbowner" is the owner of the database
+//   * "dbname" is the name of the database
+//   * "table" is the name of the table or view
+func columnsHandler(w http.ResponseWriter, r *http.Request) {
+	// Do auth check, grab request info, open the database
+	sdb, err, httpStatus := collectInfo(w, r)
+	if err != nil {
+		jsonErr(w, err.Error(), httpStatus)
+		return
+	}
+	defer sdb.Close()
+
+	// Extract the table name
+	table, err := com.GetFormTable(r, false)
+	if err != nil {
+		jsonErr(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	// Make sure a table name was provided
+	if table == "" {
+		jsonErr(w, "Missing table name", http.StatusBadRequest)
+		return
+	}
+
+	// Retrieve the list of columns for the table
+	cols, err := sdb.Columns("", table)
+	if err != nil {
+		jsonErr(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	// Transfer the column info into our own structure, for better json formatting
+	var jsonCols []com.APIJSONColumn
+	for _, j := range cols {
+		jsonCols = append(jsonCols, com.APIJSONColumn{
+			Cid:       j.Cid,
+			Name:      j.Name,
+			DataType:  j.DataType,
+			NotNull:   j.NotNull,
+			DfltValue: j.DfltValue,
+			Pk:        j.Pk,
+			Autoinc:   j.Autoinc,
+			CollSeq:   j.CollSeq,
+		})
+	}
+
+	// Return the results
+	jsonData, err := json.Marshal(jsonCols)
+	if err != nil {
+		log.Printf("Error when JSON marshalling returned data in columnsHandler(): %v\n", err)
+		jsonErr(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	fmt.Fprintf(w, string(jsonData))
+}
+
 // diffHandler generates a diff between two databases or two versions of a database
 // This can be run from the command line using curl, like this:
 //   $ curl -F apikey="YOUR_API_KEY_HERE" -F dbowner_a="justinclift" -F dbname_a="Join Testing.sqlite" -F commit_a="ea12..." -F commit_b="5a7c..." https://api.dbhub.io/v1/diff

api/main.go

@@ -78,11 +78,12 @@ func main() {
 
 	// Our pages
 	http.Handle("/", gz.GzipHandler(handleWrapper(rootHandler)))
+	http.Handle("/v1/columns", gz.GzipHandler(handleWrapper(columnsHandler)))
+	http.Handle("/v1/diff", gz.GzipHandler(handleWrapper(diffHandler)))
 	http.Handle("/v1/indexes", gz.GzipHandler(handleWrapper(indexesHandler)))
 	http.Handle("/v1/query", gz.GzipHandler(handleWrapper(queryHandler)))
 	http.Handle("/v1/tables", gz.GzipHandler(handleWrapper(tablesHandler)))
 	http.Handle("/v1/views", gz.GzipHandler(handleWrapper(viewsHandler)))
-	http.Handle("/v1/diff", gz.GzipHandler(handleWrapper(diffHandler)))
 
 	// Generate the formatted server string
 	server = fmt.Sprintf("https://%s", com.Conf.Api.ServerName)
@@ -131,7 +132,7 @@ func checkAuth(w http.ResponseWriter, r *http.Request) (loggedInUser string, err
 //   2. Extracts the database owner, name, & commitID from the request
 //   3. Fetches the database from Minio (with appropriate permission checks)
 //   4. Opens the database, returning the connection handle
-// This function exists purely because this code is commonly to most of the handlers
+// This function exists purely because this code is common to most of the handlers
 func collectInfo(w http.ResponseWriter, r *http.Request) (sdb *sqlite.Conn, err error, httpStatus int) {
 	var loggedInUser string
 	loggedInUser, err = checkAuth(w, r)
@@ -167,7 +168,8 @@ func collectInfo(w http.ResponseWriter, r *http.Request) (sdb *sqlite.Conn, err
 	}
 
 	// Retrieve database file from Minio, using locally cached version if it's already there
-	newDB, err := com.RetrieveDatabaseFile(bucket, id)
+	var newDB string
+	newDB, err = com.RetrieveDatabaseFile(bucket, id)
 	if err != nil {
 		httpStatus = http.StatusNotFound
 		return

common/types.go

@@ -197,6 +197,18 @@ type ActivityStats struct {
 	Viewed    []ActivityRow
 }
 
+// APIJSONColumn is a copy of the Column type from github.com/gwenn/gosqlite, but including JSON field name info
+type APIJSONColumn struct {
+	Cid       int    `json:"column_id"`
+	Name      string `json:"name"`
+	DataType  string `json:"data_type"`
+	NotNull   bool   `json:"not_null"`
+	DfltValue string `json:"default_value"`
+	Pk        int    `json:"primary_key"`
+	Autoinc   bool   `json:"autoinc"`
+	CollSeq   string `json:"collation_seq"`
+}
+
 type APIKey struct {
 	Key         string    `json:"key"`
 	DateCreated time.Time `json:"date_created"`

common/userinput.go

@@ -259,6 +259,34 @@ func GetFormTag(r *http.Request) (tag string, err error) {
 	return c, nil
 }
 
+// Return the table name present in the GET or POST/PUT data.
+func GetFormTable(r *http.Request, allowGet bool) (string, error) {
+	// Retrieve the variable from the GET or POST/PUT data
+	var t, table string
+	if allowGet {
+		t = r.FormValue("table")
+	} else {
+		t = r.PostFormValue("table")
+	}
+
+	// If no table name given, return
+	if t == "" {
+		return "", nil
+	}
+
+	// Unescape, then validate the owner name
+	table, err := url.QueryUnescape(t)
+	if err != nil {
+		return "", err
+	}
+	err = ValidatePGTable(table)
+	if err != nil {
+		log.Printf("Validation failed for table name: %s", err)
+		return "", err
+	}
+	return table, nil
+}
+
 // Return the username, database, and commit (if any) present in the form data.
 func GetFormUDC(r *http.Request) (string, string, string, error) {
 	// Extract the username