Add ability to pass arbitrary query params (#101)

```ts
Employee.where({ active: true }).qp({ debug: true })
```

Would hit `/employees?filter[active]=true&debug=true`

Author: richmolj

src/model.ts

@@ -752,6 +752,10 @@ export class JSORMBase {
     return this.scope().per(size)
   }
 
+  static extraParams<I extends typeof JSORMBase>(this: I, clause: any) {
+    return this.scope().extraParams(clause)
+  }
+
   static order<I extends typeof JSORMBase>(
     this: I,
     clause: SortScope | string

src/scope.ts

@@ -47,6 +47,7 @@ export class Scope<T extends typeof JSORMBase = typeof JSORMBase> {
   private _extra_fields: FieldScope = {}
   private _include: IncludeScopeHash = {}
   private _stats: StatsScope = {}
+  private _extraParams: any = {}
 
   constructor(model: T) {
     this.model = model
@@ -112,6 +113,17 @@ export class Scope<T extends typeof JSORMBase = typeof JSORMBase> {
     return copy
   }
 
+  extraParams(clause: any): Scope<T> {
+    const copy = this.copy()
+
+    for (const key in clause) {
+      if (clause.hasOwnProperty(key)) {
+        copy._extraParams[key] = clause[key]
+      }
+    }
+    return copy
+  }
+
   stats(clause: StatsScope): Scope<T> {
     const copy = this.copy()
 
@@ -210,6 +222,10 @@ export class Scope<T extends typeof JSORMBase = typeof JSORMBase> {
 
     this._mergeAssociationQueryParams(qp, this._associations)
 
+    Object.keys(this._extraParams).forEach((k) => {
+      qp[k] = this._extraParams[k]
+    })
+
     return qp
   }
 

test/unit/scope.test.ts

@@ -203,6 +203,7 @@ describe("Scope", () => {
         .select({ pets: ["type"] })
         .selectExtra({ people: ["net_worth"] })
         .stats({ total: "count" })
+        .extraParams({ foo: "bar" })
         .includes({ a: ["b", { c: "d" }] })
       const qp = scope.asQueryParams()
 
@@ -226,6 +227,7 @@ describe("Scope", () => {
         stats: {
           total: "count"
         },
+        foo: "bar",
         include: "a.b,a.c.d"
       })
     })
@@ -259,6 +261,23 @@ describe("Scope", () => {
         expect(scope.toQueryParams()).to.eq(undefined)
       })
     })
+
+    describe("when arbitrary query params added", () => {
+      it("adds to the param string", () => {
+        scope = scope.extraParams({ foo: "bar", bar: "baz" })
+        expect((<string>scope.toQueryParams())).to.eq("foo=bar&bar=baz")
+      })
+
+      it("casts arrays correctly", () => {
+        scope = scope.extraParams({ foo: "bar,baz" })
+        expect((<string>scope.toQueryParams())).to.eq("foo=bar,baz")
+      })
+
+      it("casts objects correctly", () => {
+        scope = scope.extraParams({ foo: { bar: "baz" } })
+        expect((<string>scope.toQueryParams())).to.eq("foo[bar]=baz")
+      })
+    })
   })
 
   describe("#copy", () => {