Accept random seed from UI for random sorting (#328)

pkg/models/querybuilder_sql.go

@@ -93,6 +93,8 @@ func getSort(sort string, direction string, tableName string) string {
 		direction = "ASC"
 	}
 
+	const randomSeedPrefix = "random_"
+
 	if strings.Contains(sort, "_count") {
 		var relationTableName = strings.Split(sort, "_")[0] // TODO: pluralize?
 		colName := getColumn(relationTableName, "id")
@@ -100,12 +102,18 @@ func getSort(sort string, direction string, tableName string) string {
 	} else if strings.Compare(sort, "filesize") == 0 {
 		colName := getColumn(tableName, "size")
 		return " ORDER BY cast(" + colName + " as integer) " + direction
+	} else if strings.HasPrefix(sort, randomSeedPrefix) {
+		// seed as a parameter from the UI
+		// turn the provided seed into a float
+		seedStr := "0." + sort[len(randomSeedPrefix):]
+		seed, err := strconv.ParseFloat(seedStr, 32)
+		if err != nil {
+			// fallback to default seed
+			seed = randomSortFloat
+		}
+		return getRandomSort(tableName, direction, seed)
 	} else if strings.Compare(sort, "random") == 0 {
-		// https://stackoverflow.com/a/24511461
+		return getRandomSort(tableName, direction, randomSortFloat)
-		// TODO seed as a parameter from the UI
-		colName := getColumn(tableName, "id")
-		randomSortString := strconv.FormatFloat(randomSortFloat, 'f', 16, 32)
-		return " ORDER BY " + "(substr(" + colName + " * " + randomSortString + ", length(" + colName + ") + 2))" + " " + direction
 	} else {
 		colName := getColumn(tableName, sort)
 		var additional string
@@ -122,6 +130,13 @@ func getSort(sort string, direction string, tableName string) string {
 	}
 }
 
+func getRandomSort(tableName string, direction string, seed float64) string {
+	// https://stackoverflow.com/a/24511461
+	colName := getColumn(tableName, "id")
+	randomSortString := strconv.FormatFloat(seed, 'f', 16, 32)
+	return " ORDER BY " + "(substr(" + colName + " * " + randomSortString + ", length(" + colName + ") + 2))" + " " + direction
+}
+
 func getSearch(columns []string, q string) string {
 	// TODO - susceptible to SQL injection
 	var likeClauses []string

ui/v2/src/models/list-filter/filter.ts

@@ -46,6 +46,7 @@ export class ListFilterModel {
   public criterionOptions: ICriterionOption[] = [];
   public criteria: Array<Criterion<any, any>> = [];
   public totalCount: number = 0;
+  public randomSeed: number = -1;
 
   private static createCriterionOption(criterion: CriterionType) {
     return new CriterionOption(Criterion.getLabel(criterion), criterion);
@@ -153,6 +154,19 @@ export class ListFilterModel {
     const params = rawParms as IQueryParameters;
     if (params.sortby !== undefined) {
       this.sortBy = params.sortby;
+
+      // parse the random seed if provided
+      const randomPrefix = "random_";
+      if (this.sortBy && this.sortBy.startsWith(randomPrefix)) {
+        let seedStr = this.sortBy.substring(randomPrefix.length);
+
+        this.sortBy = "random";
+        try {
+          this.randomSeed = Number.parseInt(seedStr);
+        } catch (err) {
+          // ignore
+        }
+      }
     }
     if (params.sortdir === "asc" || params.sortdir === "desc") {
       this.sortDirection = params.sortdir;
@@ -187,6 +201,28 @@ export class ListFilterModel {
     }
   }
 
+  private setRandomSeed() {
+    if (this.sortBy == "random") {
+      // #321 - set the random seed if it is not set
+      if (this.randomSeed == -1) {
+        // generate 8-digit seed
+        this.randomSeed = Math.floor(Math.random() * Math.pow(10, 8));
+      }
+    } else {
+      this.randomSeed = -1;
+    }
+  }
+
+  private getSortBy(): string | undefined {
+    this.setRandomSeed();
+
+    if (this.sortBy == "random") {
+      return this.sortBy + "_" + this.randomSeed.toString();
+    }
+
+    return this.sortBy;
+  }
+
   public makeQueryParameters(): string {
     const encodedCriteria: string[] = [];
     this.criteria.forEach((criterion) => {
@@ -198,8 +234,9 @@ export class ListFilterModel {
       encodedCriteria.push(jsonCriterion);
     });
 
+    
     const result = {
-      sortby: this.sortBy,
+      sortby: this.getSortBy(),
       sortdir: this.sortDirection,
       disp: this.displayMode,
       q: this.searchTerm,
@@ -216,7 +253,7 @@ export class ListFilterModel {
       q: this.searchTerm,
       page: this.currentPage,
       per_page: this.itemsPerPage,
-      sort: this.sortBy,
+      sort: this.getSortBy(),
       direction: this.sortDirection === "asc" ? SortDirectionEnum.Asc : SortDirectionEnum.Desc,
     };
   }