DataFrame: expose an object array as a data frame (#23494)

2020-04-11 07:08:22 -07:00
parent 6cb7d95916
commit 6f1a25a896
12 changed files with 326 additions and 31 deletions
@@ -0,0 +1,119 @@
+import { Field, FieldType, DataFrame } from '../types/dataFrame';
+import { vectorToArray } from '../vector/vectorToArray';
+import { Vector, QueryResultMeta } from '../types';
+import { guessFieldTypeFromNameAndValue, toDataFrameDTO } from './processDataFrame';
+import { FunctionalVector } from '../vector/FunctionalVector';
+
+export type ValueConverter<T = any> = (val: any) => T;
+
+const NOOP: ValueConverter = v => v;
+
+class ArrayPropertyVector<T = any> implements Vector<T> {
+  converter = NOOP;
+
+  constructor(private source: any[], private prop: string) {}
+
+  get length(): number {
+    return this.source.length;
+  }
+
+  get(index: number): T {
+    return this.converter(this.source[index][this.prop]);
+  }
+
+  toArray(): T[] {
+    return vectorToArray(this);
+  }
+
+  toJSON(): T[] {
+    return vectorToArray(this);
+  }
+}
+
+/**
+ * The ArrayDataFrame takes an array of objects and presents it as a DataFrame
+ *
+ * @alpha
+ */
+export class ArrayDataFrame<T = any> extends FunctionalVector<T> implements DataFrame {
+  name?: string;
+  refId?: string;
+  meta?: QueryResultMeta;
+
+  private theFields: Field[] = [];
+
+  constructor(private source: T[], names?: string[]) {
+    super();
+
+    const first: any = source.length ? source[0] : {};
+    if (names) {
+      this.theFields = names.map(name => {
+        return {
+          name,
+          type: guessFieldTypeFromNameAndValue(name, first[name]),
+          config: {},
+          values: new ArrayPropertyVector(source, name),
+        };
+      });
+    } else {
+      this.setFieldsFromObject(first);
+    }
+  }
+
+  /**
+   * Add a field for each property in the object.  This will guess the type
+   */
+  setFieldsFromObject(obj: any) {
+    this.theFields = Object.keys(obj).map(name => {
+      return {
+        name,
+        type: guessFieldTypeFromNameAndValue(name, obj[name]),
+        config: {},
+        values: new ArrayPropertyVector(this.source, name),
+      };
+    });
+  }
+
+  /**
+   * Configure how the object property is passed to the data frame
+   */
+  setFieldType(name: string, type: FieldType, converter?: ValueConverter): Field {
+    let field = this.fields.find(f => f.name === name);
+    if (field) {
+      field.type = type;
+    } else {
+      field = {
+        name,
+        type,
+        config: {},
+        values: new ArrayPropertyVector(this.source, name),
+      };
+      this.fields.push(field);
+    }
+    (field.values as any).converter = converter ?? NOOP;
+    return field;
+  }
+
+  get fields(): Field[] {
+    return this.theFields;
+  }
+
+  // Defined for Vector interface
+  get length() {
+    return this.source.length;
+  }
+
+  /**
+   * Get an object with a property for each field in the DataFrame
+   */
+  get(idx: number): T {
+    return this.source[idx];
+  }
+
+  /**
+   * The simplified JSON values used in JSON.stringify()
+   */
+  toJSON() {
+    return toDataFrameDTO(this);
+  }
+}