Add json-schemas package to mono repo

packages/json-schemas/src/schema_validator.ts

@@ -0,0 +1,28 @@
+import values = require('lodash.values');
+import {Validator, ValidatorResult, Schema} from 'jsonschema';
+import {schemas} from './schemas';
+
+export class SchemaValidator {
+    private validator: Validator;
+    constructor() {
+        this.validator = new Validator();
+        for (const schema of values(schemas)) {
+            this.validator.addSchema(schema, schema.id);
+        }
+    }
+    public addSchema(schema: Schema) {
+        this.validator.addSchema(schema, schema.id);
+    }
+    // In order to validate a complex JS object using jsonschema, we must replace any complex
+    // sub-types (e.g BigNumber) with a simpler string representation. Since BigNumber and other
+    // complex types implement the `toString` method, we can stringify the object and
+    // then parse it. The resultant object can then be checked using jsonschema.
+    public validate(instance: any, schema: Schema): ValidatorResult {
+        const jsonSchemaCompatibleObject = JSON.parse(JSON.stringify(instance));
+        return this.validator.validate(jsonSchemaCompatibleObject, schema);
+    }
+    public isValid(instance: any, schema: Schema): boolean {
+        const isValid = this.validate(instance, schema).errors.length === 0;
+        return isValid;
+    }
+}