MESSAGE: The request failed validation

[tiendq]

Issue Summary

Got error "MESSAGE: The request failed validation." in console log when requesting http://localhost:2368/a/ (post title with a single character a).

To Reproduce

1. grunt dev --server
2. Create a post with title a (just single character)
3. Visit http://localhost:2368/a/

Exception:

NAME: ValidationError
MESSAGE: The request failed validation.

level:normal

Error parsing filter
For more information on how to use filter, see http://api.ghost.org/docs/filter
ValidationError: The request failed validation.
    at new ValidationError (/Users/tiendq/Github/Ghost/node_modules/ghost-ignition/lib/errors/index.js:115:23)
    at Object.combineFilters (/Users/tiendq/Github/Ghost/core/server/models/plugins/filter.js:27:19)
    at Child.fetchAndCombineFilters (/Users/tiendq/Github/Ghost/core/server/models/plugins/filter.js:183:41)
    at Child.applyDefaultAndCustomFilters (/Users/tiendq/Github/Ghost/core/server/models/plugins/filter.js:205:22)
    at Function.findPage (/Users/tiendq/Github/Ghost/core/server/models/base/index.js:686:24)
    at modelQuery (/Users/tiendq/Github/Ghost/core/server/api/posts.js:60:32)
    at runTask (/Users/tiendq/Github/Ghost/core/server/lib/promise/pipeline.js:16:24)
    at /Users/tiendq/Github/Ghost/core/server/lib/promise/pipeline.js:26:20
    at tryCatcher (/Users/tiendq/Github/Ghost/node_modules/bluebird/js/release/util.js:16:23)
    at Object.gotValue (/Users/tiendq/Github/Ghost/node_modules/bluebird/js/release/reduce.js:157:18)
    at Object.gotAccum (/Users/tiendq/Github/Ghost/node_modules/bluebird/js/release/reduce.js:144:25)
    at Object.tryCatcher (/Users/tiendq/Github/Ghost/node_modules/bluebird/js/release/util.js:16:23)
    at Promise._settlePromiseFromHandler (/Users/tiendq/Github/Ghost/node_modules/bluebird/js/release/promise.js:512:31)
    at Promise._settlePromise (/Users/tiendq/Github/Ghost/node_modules/bluebird/js/release/promise.js:569:18)
    at Promise._settlePromise0 (/Users/tiendq/Github/Ghost/node_modules/bluebird/js/release/promise.js:614:10)
    at Promise._settlePromises (/Users/tiendq/Github/Ghost/node_modules/bluebird/js/release/promise.js:693:18)

Error: Query Error: unrecognized text "a" in filter at char 7
slug:-a+published_at:<='20
------^
    at Object.lexer.parseError (/Users/tiendq/Github/Ghost/node_modules/ghost-gql/dist/parser.js:703:11)
    at Object.next (/Users/tiendq/Github/Ghost/node_modules/ghost-gql/dist/parser.js:586:25)
    at Object.lex (/Users/tiendq/Github/Ghost/node_modules/ghost-gql/dist/parser.js:596:22)
    at lex (/Users/tiendq/Github/Ghost/node_modules/ghost-gql/dist/parser.js:206:27)
    at Parser.parse (/Users/tiendq/Github/Ghost/node_modules/ghost-gql/dist/parser.js:219:26)
    at Object.exports.parse (/Users/tiendq/Github/Ghost/node_modules/ghost-gql/lib/gql.js:19:19)
    at /Users/tiendq/Github/Ghost/core/server/models/plugins/filter.js:24:46
    at arrayMap (/Users/tiendq/Github/Ghost/node_modules/lodash/lodash.js:639:23)
    at Function.map (/Users/tiendq/Github/Ghost/node_modules/lodash/lodash.js:9554:14)
    at Object.combineFilters (/Users/tiendq/Github/Ghost/core/server/models/plugins/filter.js:23:24)
    at Child.fetchAndCombineFilters (/Users/tiendq/Github/Ghost/core/server/models/plugins/filter.js:183:41)
    at Child.applyDefaultAndCustomFilters (/Users/tiendq/Github/Ghost/core/server/models/plugins/filter.js:205:22)
    at Function.findPage (/Users/tiendq/Github/Ghost/core/server/models/base/index.js:686:24)
    at modelQuery (/Users/tiendq/Github/Ghost/core/server/api/posts.js:60:32)
    at runTask (/Users/tiendq/Github/Ghost/core/server/lib/promise/pipeline.js:16:24)
    at /Users/tiendq/Github/Ghost/core/server/lib/promise/pipeline.js:26:20

Technical details:

• Ghost Version: 1.23.1
• Node Version: 8.11.1
• Browser/OS: macOS 10.12.6

[kirrg001]

Duplicate of #9173.