#399

frontend/src/lib/postImportRows.ts

@@ -16,6 +16,10 @@ const rowChanged = (
     || JSON.stringify (previous.provenance) !== JSON.stringify (next.provenance)
     || JSON.stringify (previous.tagSources ?? { }) !== JSON.stringify (next.tagSources ?? { })
 
+const buildResetSnapshot = (row: PostImportRow) => ({
+    url: row.url,
+    attributes: row.attributes })
+
 
 export const processableImportRows = (rows: PostImportRow[]): PostImportRow[] =>
     rows.filter (row => {
@@ -111,7 +115,11 @@ export const mergeValidatedImportRows = (
 		: previous.baseWarnings,
 	    validationErrors: row.validationErrors,
 	    status: row.status,
-	    metadataUrl: row.metadataUrl }
+	    metadataUrl: row.metadataUrl,
+	    resetSnapshot:
+		row.metadataUrl !== previous.metadataUrl
+		? buildResetSnapshot (row)
+		: previous.resetSnapshot }
     })
 }
 
@@ -154,6 +162,7 @@ export const mergePreviewImportRows = (
 	    tagSources: mergedTagSources,
 	    skipReason: row.skipReason,
 	    existingPostId: row.existingPostId,
+	    resetSnapshot: row.resetSnapshot,
 	    createdPostId: previous.createdPostId,
 	    importStatus: previous.importStatus,
 	    importErrors: previous.importErrors }
@@ -214,3 +223,8 @@ export const retryImportRow = (
 	row.sourceRow === sourceRow && row.importStatus === 'failed'
 	? { ...row, importStatus: 'pending', importErrors: undefined }
 	: row)
+
+export const initialisePreviewRows = (rows: PostImportRow[]): PostImportRow[] =>
+    rows.map (row => ({
+	...row,
+	resetSnapshot: buildResetSnapshot (row) }))

frontend/src/lib/postImportStorage.ts

@@ -1,4 +1,5 @@
 import type { PostImportOrigin,
+	      PostImportResetSnapshot,
 	      PostImportRow,
 	      PostImportSession,
 	      PostImportStatus,
@@ -137,6 +138,24 @@ const hasOnlyKeys = (
 ): boolean =>
     Object.keys (value).every (key => allowedKeys.includes (key))
 
+const sanitiseResetSnapshot = (value: unknown): PostImportResetSnapshot | null => {
+    if (!(isPlainObject (value)))
+      return null
+    if (typeof value.url !== 'string')
+      return null
+    if (!(isPlainObject (value.attributes)))
+      return null
+    if (!(hasOnlyKeys (value.attributes, ATTRIBUTE_KEYS)))
+      return null
+    if (!(Object.values (value.attributes).every (entry =>
+	typeof entry === 'string' || typeof entry === 'number')))
+      return null
+
+    return {
+	url: value.url,
+	attributes: value.attributes as Record<string, string | number> }
+}
+
 
 const sanitiseRow = (value: unknown): PostImportRow | null => {
     if (!(isPlainObject (value)))
@@ -166,8 +185,11 @@ const sanitiseRow = (value: unknown): PostImportRow | null => {
 
     const validationErrors = ensureStringListRecord (value.validationErrors)
     const fieldWarnings = ensureStringListRecord (value.fieldWarnings)
+    const resetSnapshot = sanitiseResetSnapshot (value.resetSnapshot)
     if (validationErrors == null || fieldWarnings == null)
       return null
+    if (resetSnapshot == null)
+      return null
 
     const importErrors =
 	value.importErrors == null
@@ -215,6 +237,7 @@ const sanitiseRow = (value: unknown): PostImportRow | null => {
 	existingPostId:
 	    isPositiveInteger (value.existingPostId) ? Number (value.existingPostId) : undefined,
 	metadataUrl: typeof value.metadataUrl === 'string' ? value.metadataUrl : undefined,
+	resetSnapshot,
 	createdPostId:
 	    isPositiveInteger (value.createdPostId) ? Number (value.createdPostId) : undefined,
 	importStatus: value.importStatus }

frontend/src/lib/postImportTypes.ts

@@ -9,6 +9,10 @@ export type PostImportSkipReason = 'existing'
 export type PostImportResultStatus = 'created' | 'skipped' | 'failed'
 export type PostImportAttributeValue = string | number
 
+export type PostImportResetSnapshot = {
+    url:        string
+    attributes: Record<string, PostImportAttributeValue> }
+
 export type PostImportRow = {
     sourceRow:         number
     url:               string
@@ -23,6 +27,7 @@ export type PostImportRow = {
     skipReason?:       PostImportSkipReason
     existingPostId?:   number
     metadataUrl?:      string
+    resetSnapshot:     PostImportResetSnapshot
     createdPostId?:    number
     importStatus?:     PostImportStatus }