diff --git a/packages/crud-request/src/interfaces/create-query-params.interface.ts b/packages/crud-request/src/interfaces/create-query-params.interface.ts
index 2bade000..006af756 100644
--- a/packages/crud-request/src/interfaces/create-query-params.interface.ts
+++ b/packages/crud-request/src/interfaces/create-query-params.interface.ts
@@ -9,13 +9,13 @@ import {
   SCondition,
 } from '../types';
 
-export interface CreateQueryParams {
-  fields?: QueryFields;
-  search?: SCondition;
-  filter?: QueryFilter | QueryFilterArr | Array<QueryFilter | QueryFilterArr>;
-  or?: QueryFilter | QueryFilterArr | Array<QueryFilter | QueryFilterArr>;
-  join?: QueryJoin | QueryJoinArr | Array<QueryJoin | QueryJoinArr>;
-  sort?: QuerySort | QuerySortArr | Array<QuerySort | QuerySortArr>;
+export interface CreateQueryParams<K extends string = string> {
+  fields?: QueryFields<K>;
+  search?: SCondition<K>;
+  filter?: QueryFilter<K> | QueryFilterArr<K> | Array<QueryFilter<K> | QueryFilterArr<K>>;
+  or?: QueryFilter<K> | QueryFilterArr<K> | Array<QueryFilter<K> | QueryFilterArr<K>>;
+  join?: QueryJoin<K> | QueryJoinArr<K> | Array<QueryJoin<K> | QueryJoinArr<K>>;
+  sort?: QuerySort<K> | QuerySortArr<K> | Array<QuerySort<K> | QuerySortArr<K>>;
   limit?: number;
   offset?: number;
   page?: number;
diff --git a/packages/crud-request/src/request-query.builder.ts b/packages/crud-request/src/request-query.builder.ts
index 82aa4d99..ed468e7a 100644
--- a/packages/crud-request/src/request-query.builder.ts
+++ b/packages/crud-request/src/request-query.builder.ts
@@ -28,7 +28,7 @@ import {
 } from './types';
 
 // tslint:disable:variable-name ban-types
-export class RequestQueryBuilder {
+export class RequestQueryBuilder<K extends string = string> {
   constructor() {
     this.setParamNames();
   }
@@ -95,7 +95,7 @@ export class RequestQueryBuilder {
     return this.queryString;
   }
 
-  select(fields: QueryFields): this {
+  select(fields: QueryFields<K>): this {
     if (isArrayFull(fields)) {
       validateFields(fields);
       this.queryObject[this.paramNames.fields] = fields.join(this.options.delimStr);
@@ -103,44 +103,52 @@ export class RequestQueryBuilder {
     return this;
   }
 
-  search(s: SCondition) {
+  search(s: SCondition<K>) {
     if (!isNil(s) && isObject(s)) {
       this.queryObject[this.paramNames.search] = JSON.stringify(s);
     }
     return this;
   }
 
-  setFilter(f: QueryFilter | QueryFilterArr | Array<QueryFilter | QueryFilterArr>): this {
+  setFilter(
+    f: QueryFilter<K> | QueryFilterArr<K> | Array<QueryFilter<K> | QueryFilterArr<K>>,
+  ): this {
     this.setCondition(f, 'filter');
     return this;
   }
 
-  setOr(f: QueryFilter | QueryFilterArr | Array<QueryFilter | QueryFilterArr>): this {
+  setOr(
+    f: QueryFilter<K> | QueryFilterArr<K> | Array<QueryFilter<K> | QueryFilterArr<K>>,
+  ): this {
     this.setCondition(f, 'or');
     return this;
   }
 
-  setJoin(j: QueryJoin | QueryJoinArr | Array<QueryJoin | QueryJoinArr>): this {
+  setJoin(
+    j: QueryJoin<K> | QueryJoinArr<K> | Array<QueryJoin<K> | QueryJoinArr<K>>,
+  ): this {
     if (!isNil(j)) {
       const param = this.checkQueryObjectParam('join', []);
       this.queryObject[param] = [
         ...this.queryObject[param],
         ...(Array.isArray(j) && !isString(j[0])
-          ? (j as Array<QueryJoin | QueryJoinArr>).map((o) => this.addJoin(o))
-          : [this.addJoin(j as QueryJoin | QueryJoinArr)]),
+          ? (j as Array<QueryJoin<K> | QueryJoinArr<K>>).map((o) => this.addJoin(o))
+          : [this.addJoin(j as QueryJoin<K> | QueryJoinArr<K>)]),
       ];
     }
     return this;
   }
 
-  sortBy(s: QuerySort | QuerySortArr | Array<QuerySort | QuerySortArr>): this {
+  sortBy(
+    s: QuerySort<K> | QuerySortArr<K> | Array<QuerySort<K> | QuerySortArr<K>>,
+  ): this {
     if (!isNil(s)) {
       const param = this.checkQueryObjectParam('sort', []);
       this.queryObject[param] = [
         ...this.queryObject[param],
         ...(Array.isArray(s) && !isString(s[0])
-          ? (s as Array<QuerySort | QuerySortArr>).map((o) => this.addSortBy(o))
-          : [this.addSortBy(s as QuerySort | QuerySortArr)]),
+          ? (s as Array<QuerySort<K> | QuerySortArr<K>>).map((o) => this.addSortBy(o))
+          : [this.addSortBy(s as QuerySort<K> | QuerySortArr<K>)]),
       ];
     }
     return this;
@@ -167,7 +175,7 @@ export class RequestQueryBuilder {
   }
 
   cond(
-    f: QueryFilter | QueryFilterArr,
+    f: QueryFilter<K> | QueryFilterArr<K>,
     cond: 'filter' | 'or' | 'search' = 'search',
   ): string {
     const filter = Array.isArray(f) ? { field: f[0], operator: f[1], value: f[2] } : f;
@@ -182,7 +190,7 @@ export class RequestQueryBuilder {
     );
   }
 
-  private addJoin(j: QueryJoin | QueryJoinArr): string {
+  private addJoin(j: QueryJoin<K> | QueryJoinArr<K>): string {
     const join = Array.isArray(j) ? { field: j[0], select: j[1] } : j;
     validateJoin(join);
     const d = this.options.delim;
@@ -191,7 +199,7 @@ export class RequestQueryBuilder {
     return join.field + (isArrayFull(join.select) ? d + join.select.join(ds) : '');
   }
 
-  private addSortBy(s: QuerySort | QuerySortArr): string {
+  private addSortBy(s: QuerySort<K> | QuerySortArr<K>): string {
     const sort = Array.isArray(s) ? { field: s[0], order: s[1] } : s;
     validateSort(sort);
     const ds = this.options.delimStr;
@@ -199,7 +207,7 @@ export class RequestQueryBuilder {
     return sort.field + ds + sort.order;
   }
 
-  private createFromParams(params: CreateQueryParams): this {
+  private createFromParams(params: CreateQueryParams<K>): this {
     this.select(params.fields);
     this.search(params.search);
     this.setFilter(params.filter);
@@ -227,7 +235,7 @@ export class RequestQueryBuilder {
   }
 
   private setCondition(
-    f: QueryFilter | QueryFilterArr | Array<QueryFilter | QueryFilterArr>,
+    f: QueryFilter<K> | QueryFilterArr<K> | Array<QueryFilter<K> | QueryFilterArr<K>>,
     cond: 'filter' | 'or',
   ): void {
     if (!isNil(f)) {
@@ -235,8 +243,10 @@ export class RequestQueryBuilder {
       this.queryObject[param] = [
         ...this.queryObject[param],
         ...(Array.isArray(f) && !isString(f[0])
-          ? (f as Array<QueryFilter | QueryFilterArr>).map((o) => this.cond(o, cond))
-          : [this.cond(f as QueryFilter | QueryFilterArr, cond)]),
+          ? (f as Array<QueryFilter<K> | QueryFilterArr<K>>).map((o) =>
+              this.cond(o, cond),
+            )
+          : [this.cond(f as QueryFilter<K> | QueryFilterArr<K>, cond)]),
       ];
     }
   }
diff --git a/packages/crud-request/src/types/request-query.types.ts b/packages/crud-request/src/types/request-query.types.ts
index 138e2523..77c8e835 100644
--- a/packages/crud-request/src/types/request-query.types.ts
+++ b/packages/crud-request/src/types/request-query.types.ts
@@ -1,26 +1,26 @@
-export type QueryFields = string[];
+export type QueryFields<K extends string = string> = K[];
 
-export type QueryFilter = {
-  field: string;
+export type QueryFilter<K extends string = string> = {
+  field: K;
   operator: ComparisonOperator;
   value?: any;
 };
 
-export type QueryFilterArr = [string, ComparisonOperator, any?];
+export type QueryFilterArr<K extends string = string> = [K, ComparisonOperator, any?];
 
-export type QueryJoin = {
-  field: string;
-  select?: QueryFields;
+export type QueryJoin<K extends string = string> = {
+  field: K;
+  select?: QueryFields<K>;
 };
 
-export type QueryJoinArr = [string, QueryFields?];
+export type QueryJoinArr<K extends string = string> = [K, QueryFields<K>?];
 
-export type QuerySort = {
-  field: string;
+export type QuerySort<K extends string = string> = {
+  field: K;
   order: QuerySortOperator;
 };
 
-export type QuerySortArr = [string, QuerySortOperator];
+export type QuerySortArr<K extends string = string> = [K, QuerySortOperator];
 
 export type QuerySortOperator = 'ASC' | 'DESC';
 
@@ -104,17 +104,18 @@ export type SFieldOperator = {
 
 export type SField = SPrimitivesVal | SFieldOperator;
 
-export type SFields = {
-  [key: string]: SField | Array<SFields | SConditionAND> | undefined;
-  $or?: Array<SFields | SConditionAND>;
+export type SFields<K extends string = string> = {
+  $or?: Array<SFields<K> | SConditionAND<K>>;
   $and?: never;
+} & {
+  [key in K]?: SField | Array<SFields<K> | SConditionAND<K>> | undefined;
 };
 
-export type SConditionAND = {
-  $and?: Array<SFields | SConditionAND>;
+export type SConditionAND<K extends string = string> = {
+  $and?: Array<SFields<K> | SConditionAND<K>>;
   $or?: never;
 };
 
 export type SConditionKey = '$and' | '$or';
 
-export type SCondition = SFields | SConditionAND;
+export type SCondition<K extends string = string> = SFields<K> | SConditionAND<K>;