Add substring function

jakubknejzlik · Mar 18, 2024 · a27e001 · a27e001
1 parent 235da3e
commit a27e001
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Showing 3 changed files with 23 additions and 0 deletions.
diff --git a/src/Function.test.ts b/src/Function.test.ts
@@ -29,6 +29,9 @@ describe("Expression", () => {
         flavor
       )
     ).toEqual('(YEAR("2024-01-01") - YEAR("2025-01-01"))');
+    expect(Fn.substring("year", 1, 10).toSQL(flavor)).toEqual(
+      "SUBSTRING(`year`,1,10)"
+    );
   });
   it("should support value composition", () => {
     expect(Fn.sum(Fn.ifnull("foo", Q.S`123`)).toSQL(flavor)).toEqual(

diff --git a/src/Function.ts b/src/Function.ts
@@ -79,6 +79,18 @@ export const Function = {
   formatDate: (date: Dayjs) => {
     return Q.expr(`'${formatDayjs(date)}'`);
   },
+  substring: (
+    string: string,
+    start: ExpressionValue,
+    length: ExpressionValue
+  ) => {
+    return new FunctionExpression(
+      "SUBSTRING",
+      string,
+      Q.value(start),
+      Q.value(length)
+    );
+  },
   string: (value: string) => {
     return Q.expr(Expression.escapeString(`${value}`));
   },

diff --git a/src/stories/3_Function.stories.mdx b/src/stories/3_Function.stories.mdx
@@ -59,6 +59,14 @@ Compute a single result from a set of input values:
 
 <QueryPreview code={`Fn.count('column');`} />
 
+### String Functions
+
+Manipulate and format date values:
+
+**Year**
+
+<QueryPreview code={`Fn.substring('created_at',1,4);`} />
+
 ### Date Functions
 
 Manipulate and format date values: