42 lines
1.3 KiB
Markdown
42 lines
1.3 KiB
Markdown
# Import / Export Pattern
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Canonical file transfer UX patterns for Go web applications:
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- file import forms (CSV/JSON and similar)
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- validation preview tables before confirm
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- confirm step with human-readable summary
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- export controls (format + scope + options)
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- predictable file download behavior and filenames
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This pattern covers UI and UX contracts. Business-specific validation and file schemas remain in
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the host project's own architecture docs.
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## Export Handler Sketch
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```go
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func ExportCSV(c *gin.Context) {
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c.Header("Content-Type", "text/csv; charset=utf-8")
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c.Header("Content-Disposition", `attachment; filename="export.csv"`)
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c.Writer.Write([]byte{0xEF, 0xBB, 0xBF})
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w := csv.NewWriter(c.Writer)
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w.Comma = ';'
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w.Write([]string{"ID", "Name", "Price"})
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err := svc.StreamRows(ctx, filters, func(row Row) error {
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return w.Write([]string{row.ID, row.Name, formatPrice(row.Price)})
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})
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w.Flush()
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if err != nil {
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slog.Error("csv export failed mid-stream", "err", err)
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}
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}
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```
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## Locale Notes
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- BOM avoids broken UTF-8 in Excel on Windows.
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- Semicolon avoids single-column imports in RU/EU locales.
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- Decimal comma keeps numbers numeric in Excel.
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- `DD.MM.YYYY` is preferred over ISO dates for user-facing spreadsheet exports.
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