party/internal/data/issues.go

package data

import (
	"time"
	"party.at/party/internal/validator"
	"database/sql"
	"errors"
	"context"
	"fmt"
)

type Issue struct {
	ID          int64     `json:"id"`
	Title       string    `json:"title"`
	Description string    `json:"description"`
	StartTime   time.Time `json:"start_time"`
	EndTime     time.Time `json:"end_time"`
	Created     time.Time `json:"created"`
	Version     int32     `json:"version"`
}

func ValidateIssue(v *validator.Validator, issue *Issue) {
	v.Check(issue.Title != "",             "title",       "must be provided")
	v.Check(len(issue.Title) <= 500,       "title",       "must not be more than 500 bytes long")
	v.Check(issue.Description != "",       "description", "must be provided")
	v.Check(len(issue.Description) <= 500, "description", "must not be greater than 500 bytes long")
	// v.Check(issue.StartTime != "",         "start_time",  "must be provided")
	// v.Check(len(issue.StartTime) <= 500,   "start_time",  "must not be more than 500 bytes long")
	// v.Check(issue.EndTime != "",           "end_time",    "must be provided")
	// v.Check(len(issue.EndTime) <= 500,     "end_time",    "must not be more than 500 bytes long")
}

type IssueModel struct {
	DB *sql.DB
}

func (m IssueModel) Insert(issue *Issue) error {
	query := `
INSERT INTO issues (title, description, start_time, end_time)
VALUES ($1, $2, $3, $4)
RETURNING id, created, version`

	args := []interface{}{
		issue.Title,
		issue.Description,
		issue.StartTime,
		issue.EndTime,
	}

	return m.DB.QueryRow(query, args...).Scan(
		&issue.ID,
		&issue.Created,
		&issue.Version,
	)
}

// Add a placeholder method for fetching a specific record from the issues table.
func (m IssueModel) Get(id int64) (*Issue, error) {
	if id < 1 {
		return nil, ErrRecordNotFound
	}

	// Define the SQL query for retrieving the issue data.
	query :=`
SELECT id, title, description, start_time, end_time, created, version
FROM issues
WHERE id = $1`

	// Declare a Issue struct to hold the data returned by the query.
	var issue Issue

	// Execute the query using the QueryRow() method, passing in the provided id value
	// as a placeholder parameter, and scan the response data into the fields of the
	// Issue struct. Importantly, notice that we need to convert the scan target for the
	// genres column using the pq.Array() adapter function again.
	err := m.DB.QueryRow(query, id).Scan(
		&issue.ID,
		&issue.Title,
		&issue.Description,
		&issue.StartTime,
		&issue.EndTime,
		&issue.Created,
		&issue.Version,
	)

	// Handle any errors. If there was no matching issue found, Scan() will return
	// a sql.ErrNoRows error. We check for this and return our custom ErrRecordNotFound
	// error instead.
	if err != nil {
		switch {
		case errors.Is(err, sql.ErrNoRows):
			return nil, ErrRecordNotFound
		default:
			return nil, err
		}
	}
	// Otherwise, return a pointer to the Issue struct.
	return &issue, nil
}

func (m IssueModel) Update(issue *Issue) error {
	query := `
	UPDATE issues
	SET title = $1, description = $2, start_time = $3, end_time = $4, version = version + 1
	WHERE id = $5 AND version = $6
	RETURNING version`

	// Create an args slice containing the values for the placeholder parameters.
	args := []interface{}{
		issue.Title,
		issue.Description,
		issue.StartTime,
		issue.EndTime,
		issue.ID,
		issue.Version,
	}

	// Use the QueryRow() method to execute the query, passing in the args slice as a
	// variadic parameter and scanning the new version value into the issue struct.
	err := m.DB.QueryRow(query, args...).Scan(&issue.Version)
	if err != nil {
		switch {
		case errors.Is(err, sql.ErrNoRows):
			return ErrEditConflict
		default:
			return err
		}
	}

	return nil
}

// Add a placeholder method for deleting a specific record from the issues table.
func (m IssueModel) Delete(id int64) error {
	if id < 1 {
		return ErrRecordNotFound
	}

	// Construct the SQL query to delete the record.
	query := `
	DELETE FROM issues
	WHERE id = $1`

	// Execute the SQL query using the Exec() method, passing in the id variable as
	// the value for the placeholder parameter. The Exec() method returns a sql.Result
	// object.
	result, err := m.DB.Exec(query, id)
	if err != nil {
		return err
	}

	// Call the RowsAffected() method on the sql.Result object to get the number of rows
	// affected by the query.
	rowsAffected, err := result.RowsAffected()
	if err != nil {
		return err
	}

	// If no rows were affected, we know that the issues table didn't contain a record
	// with the provided ID at the moment we tried to delete it. In that case we
	// return an ErrRecordNotFound error.
	if rowsAffected == 0 {
		return ErrRecordNotFound
	}

	return nil
}

func (m IssueModel) GetAll(title string, filters Filters) ([]*Issue, Metadata, error) {
	// Construct the SQL query to retrieve all issue records.
	query := fmt.Sprintf(`
	SELECT
		COUNT(*) OVER(), id, title, description, start_time, end_time, created, version
	FROM
		issues
	WHERE
		(to_tsvector('simple', title) @@ plainto_tsquery('simple', $1) OR $1 = '')
	ORDER BY
		%s %s, id ASC
	LIMIT
		$2
	OFFSET
		$3`,
		filters.sortColumn(),
		filters.sortDirection(),
	)

	// Create a context with a 3-second timeout.
	ctx, cancel := context.WithTimeout(context.Background(), 3 * time.Second)
	defer cancel()

	args := []interface{}{title, filters.limit(), filters.offset()}

	rows, err := m.DB.QueryContext(ctx, query, args...)
	if err != nil {
		return nil, Metadata{}, err
	}

	// Importantly, defer a call to rows.Close() to ensure that the resultset is closed
	// before GetAll() returns.
	defer rows.Close()

	totalRecords := 0
	issues := []*Issue{}

	// Use rows.Next to iterate through the rows in the resultset.
	for rows.Next() {
		// Initialize an empty Issue struct to hold the data for an individual issue.
		var issue Issue

		// Scan the values from the row into the Issue struct. Again, note that we're
		// using the pq.Array() adapter on the genres field here.
		err := rows.Scan(
			&totalRecords,
			&issue.ID,
			&issue.Title,
			&issue.Description,
			&issue.StartTime,
			&issue.EndTime,
			&issue.Created,
			&issue.Version,
		)

		if err != nil {
			return nil, Metadata{}, err
		}

		// Add the Issue struct to the slice.
		issues = append(issues, &issue)
	}

	// When the rows.Next() loop has finished, call rows.Err() to retrieve any error
	// that was encountered during the iteration.
	if err = rows.Err(); err != nil {
		return nil, Metadata{}, err
	}

	metadata := calculateMetadata(totalRecords, filters.Page, filters.PageSize)

	// If everything went OK, then return the slice of issues.
	return issues, metadata, nil
}